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/*-------------------------------------------------------------------------
*
* relation.h
* Definitions for planner's internal data structures.
*
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/nodes/relation.h
*
*-------------------------------------------------------------------------
*/
#ifndef RELATION_H
#define RELATION_H
#include "access/sdir.h"
#include "lib/stringinfo.h"
#include "nodes/params.h"
#include "nodes/parsenodes.h"
#include "storage/block.h"
/*
* Relids
* Set of relation identifiers (indexes into the rangetable).
*/
typedef Bitmapset *Relids;
/*
* When looking for a "cheapest path", this enum specifies whether we want
* cheapest startup cost or cheapest total cost.
*/
typedef enum CostSelector
{
STARTUP_COST, TOTAL_COST
} CostSelector;
/*
* The cost estimate produced by cost_qual_eval() includes both a one-time
* (startup) cost, and a per-tuple cost.
*/
typedef struct QualCost
{
Cost startup; /* one-time cost */
Cost per_tuple; /* per-evaluation cost */
} QualCost;
/*
* Costing aggregate function execution requires these statistics about
* the aggregates to be executed by a given Agg node. Note that the costs
* include the execution costs of the aggregates' argument expressions as
* well as the aggregate functions themselves. Also, the fields must be
* defined so that initializing the struct to zeroes with memset is correct.
*/
typedef struct AggClauseCosts
{
int numAggs; /* total number of aggregate functions */
int numOrderedAggs; /* number w/ DISTINCT/ORDER BY/WITHIN GROUP */
bool hasNonPartial; /* does any agg not support partial mode? */
bool hasNonSerial; /* is any partial agg non-serializable? */
QualCost transCost; /* total per-input-row execution costs */
Cost finalCost; /* total per-aggregated-row costs */
Size transitionSpace; /* space for pass-by-ref transition data */
} AggClauseCosts;
/*
* This enum identifies the different types of "upper" (post-scan/join)
* relations that we might deal with during planning.
*/
typedef enum UpperRelationKind
{
UPPERREL_SETOP, /* result of UNION/INTERSECT/EXCEPT, if any */
UPPERREL_GROUP_AGG, /* result of grouping/aggregation, if any */
UPPERREL_WINDOW, /* result of window functions, if any */
UPPERREL_DISTINCT, /* result of "SELECT DISTINCT", if any */
UPPERREL_ORDERED, /* result of ORDER BY, if any */
UPPERREL_FINAL /* result of any remaining top-level actions */
/* NB: UPPERREL_FINAL must be last enum entry; it's used to size arrays */
} UpperRelationKind;
/*----------
* PlannerGlobal
* Global information for planning/optimization
*
* PlannerGlobal holds state for an entire planner invocation; this state
* is shared across all levels of sub-Queries that exist in the command being
* planned.
*----------
*/
typedef struct PlannerGlobal
{
NodeTag type;
ParamListInfo boundParams; /* Param values provided to planner() */
List *subplans; /* Plans for SubPlan nodes */
List *subroots; /* PlannerInfos for SubPlan nodes */
Bitmapset *rewindPlanIDs; /* indices of subplans that require REWIND */
List *finalrtable; /* "flat" rangetable for executor */
List *finalrowmarks; /* "flat" list of PlanRowMarks */
List *resultRelations; /* "flat" list of integer RT indexes */
List *relationOids; /* OIDs of relations the plan depends on */
List *invalItems; /* other dependencies, as PlanInvalItems */
int nParamExec; /* number of PARAM_EXEC Params used */
Index lastPHId; /* highest PlaceHolderVar ID assigned */
Index lastRowMarkId; /* highest PlanRowMark ID assigned */
int lastPlanNodeId; /* highest plan node ID assigned */
bool transientPlan; /* redo plan when TransactionXmin changes? */
bool dependsOnRole; /* is plan specific to current role? */
bool parallelModeOK; /* parallel mode potentially OK? */
bool parallelModeNeeded; /* parallel mode actually required? */
} PlannerGlobal;
/* macro for fetching the Plan associated with a SubPlan node */
#define planner_subplan_get_plan(root, subplan) \
((Plan *) list_nth((root)->glob->subplans, (subplan)->plan_id - 1))
/*----------
* PlannerInfo
* Per-query information for planning/optimization
*
* This struct is conventionally called "root" in all the planner routines.
* It holds links to all of the planner's working state, in addition to the
* original Query. Note that at present the planner extensively modifies
* the passed-in Query data structure; someday that should stop.
*----------
*/
typedef struct PlannerInfo
{
NodeTag type;
Query *parse; /* the Query being planned */
PlannerGlobal *glob; /* global info for current planner run */
Index query_level; /* 1 at the outermost Query */
struct PlannerInfo *parent_root; /* NULL at outermost Query */
/*
* plan_params contains the expressions that this query level needs to
* make available to a lower query level that is currently being planned.
* outer_params contains the paramIds of PARAM_EXEC Params that outer
* query levels will make available to this query level.
*/
List *plan_params; /* list of PlannerParamItems, see below */
Bitmapset *outer_params;
/*
* simple_rel_array holds pointers to "base rels" and "other rels" (see
* comments for RelOptInfo for more info). It is indexed by rangetable
* index (so entry 0 is always wasted). Entries can be NULL when an RTE
* does not correspond to a base relation, such as a join RTE or an
* unreferenced view RTE; or if the RelOptInfo hasn't been made yet.
*/
struct RelOptInfo **simple_rel_array; /* All 1-rel RelOptInfos */
int simple_rel_array_size; /* allocated size of array */
/*
* simple_rte_array is the same length as simple_rel_array and holds
* pointers to the associated rangetable entries. This lets us avoid
* rt_fetch(), which can be a bit slow once large inheritance sets have
* been expanded.
*/
RangeTblEntry **simple_rte_array; /* rangetable as an array */
/*
* all_baserels is a Relids set of all base relids (but not "other"
* relids) in the query; that is, the Relids identifier of the final join
* we need to form. This is computed in make_one_rel, just before we
* start making Paths.
*/
Relids all_baserels;
/*
* nullable_baserels is a Relids set of base relids that are nullable by
* some outer join in the jointree; these are rels that are potentially
* nullable below the WHERE clause, SELECT targetlist, etc. This is
* computed in deconstruct_jointree.
*/
Relids nullable_baserels;
/*
* join_rel_list is a list of all join-relation RelOptInfos we have
* considered in this planning run. For small problems we just scan the
* list to do lookups, but when there are many join relations we build a
* hash table for faster lookups. The hash table is present and valid
* when join_rel_hash is not NULL. Note that we still maintain the list
* even when using the hash table for lookups; this simplifies life for
* GEQO.
*/
List *join_rel_list; /* list of join-relation RelOptInfos */
struct HTAB *join_rel_hash; /* optional hashtable for join relations */
/*
* When doing a dynamic-programming-style join search, join_rel_level[k]
* is a list of all join-relation RelOptInfos of level k, and
* join_cur_level is the current level. New join-relation RelOptInfos are
* automatically added to the join_rel_level[join_cur_level] list.
* join_rel_level is NULL if not in use.
*/
List **join_rel_level; /* lists of join-relation RelOptInfos */
int join_cur_level; /* index of list being extended */
List *init_plans; /* init SubPlans for query */
List *cte_plan_ids; /* per-CTE-item list of subplan IDs */
List *multiexpr_params; /* List of Lists of Params for
* MULTIEXPR subquery outputs */
List *eq_classes; /* list of active EquivalenceClasses */
List *canon_pathkeys; /* list of "canonical" PathKeys */
List *left_join_clauses; /* list of RestrictInfos for
* mergejoinable outer join clauses
* w/nonnullable var on left */
List *right_join_clauses; /* list of RestrictInfos for
* mergejoinable outer join clauses
* w/nonnullable var on right */
List *full_join_clauses; /* list of RestrictInfos for
* mergejoinable full join clauses */
List *join_info_list; /* list of SpecialJoinInfos */
List *append_rel_list; /* list of AppendRelInfos */
List *rowMarks; /* list of PlanRowMarks */
List *placeholder_list; /* list of PlaceHolderInfos */
List *fkey_list; /* list of ForeignKeyOptInfos */
List *query_pathkeys; /* desired pathkeys for query_planner() */
List *group_pathkeys; /* groupClause pathkeys, if any */
List *window_pathkeys; /* pathkeys of bottom window, if any */
List *distinct_pathkeys; /* distinctClause pathkeys, if any */
List *sort_pathkeys; /* sortClause pathkeys, if any */
List *initial_rels; /* RelOptInfos we are now trying to join */
/* Use fetch_upper_rel() to get any particular upper rel */
List *upper_rels[UPPERREL_FINAL + 1]; /* upper-rel RelOptInfos */
/* Result tlists chosen by grouping_planner for upper-stage processing */
struct PathTarget *upper_targets[UPPERREL_FINAL + 1];
/*
* grouping_planner passes back its final processed targetlist here, for
* use in relabeling the topmost tlist of the finished Plan.
*/
List *processed_tlist;
/* Fields filled during create_plan() for use in setrefs.c */
AttrNumber *grouping_map; /* for GroupingFunc fixup */
List *minmax_aggs; /* List of MinMaxAggInfos */
MemoryContext planner_cxt; /* context holding PlannerInfo */
double total_table_pages; /* # of pages in all tables of query */
double tuple_fraction; /* tuple_fraction passed to query_planner */
double limit_tuples; /* limit_tuples passed to query_planner */
bool hasInheritedTarget; /* true if parse->resultRelation is an
* inheritance child rel */
bool hasJoinRTEs; /* true if any RTEs are RTE_JOIN kind */
bool hasLateralRTEs; /* true if any RTEs are marked LATERAL */
bool hasDeletedRTEs; /* true if any RTE was deleted from jointree */
bool hasHavingQual; /* true if havingQual was non-null */
bool hasPseudoConstantQuals; /* true if any RestrictInfo has
* pseudoconstant = true */
bool hasRecursion; /* true if planning a recursive WITH item */
/* These fields are used only when hasRecursion is true: */
int wt_param_id; /* PARAM_EXEC ID for the work table */
struct Path *non_recursive_path; /* a path for non-recursive term */
/* These fields are workspace for createplan.c */
Relids curOuterRels; /* outer rels above current node */
List *curOuterParams; /* not-yet-assigned NestLoopParams */
/* optional private data for join_search_hook, e.g., GEQO */
void *join_search_private;
} PlannerInfo;
/*
* In places where it's known that simple_rte_array[] must have been prepared
* already, we just index into it to fetch RTEs. In code that might be
* executed before or after entering query_planner(), use this macro.
*/
#define planner_rt_fetch(rti, root) \
((root)->simple_rte_array ? (root)->simple_rte_array[rti] : \
rt_fetch(rti, (root)->parse->rtable))
/*----------
* RelOptInfo
* Per-relation information for planning/optimization
*
* For planning purposes, a "base rel" is either a plain relation (a table)
* or the output of a sub-SELECT or function that appears in the range table.
* In either case it is uniquely identified by an RT index. A "joinrel"
* is the joining of two or more base rels. A joinrel is identified by
* the set of RT indexes for its component baserels. We create RelOptInfo
* nodes for each baserel and joinrel, and store them in the PlannerInfo's
* simple_rel_array and join_rel_list respectively.
*
* Note that there is only one joinrel for any given set of component
* baserels, no matter what order we assemble them in; so an unordered
* set is the right datatype to identify it with.
*
* We also have "other rels", which are like base rels in that they refer to
* single RT indexes; but they are not part of the join tree, and are given
* a different RelOptKind to identify them.
* Currently the only kind of otherrels are those made for member relations
* of an "append relation", that is an inheritance set or UNION ALL subquery.
* An append relation has a parent RTE that is a base rel, which represents
* the entire append relation. The member RTEs are otherrels. The parent
* is present in the query join tree but the members are not. The member
* RTEs and otherrels are used to plan the scans of the individual tables or
* subqueries of the append set; then the parent baserel is given Append
* and/or MergeAppend paths comprising the best paths for the individual
* member rels. (See comments for AppendRelInfo for more information.)
*
* At one time we also made otherrels to represent join RTEs, for use in
* handling join alias Vars. Currently this is not needed because all join
* alias Vars are expanded to non-aliased form during preprocess_expression.
*
* There is also a RelOptKind for "upper" relations, which are RelOptInfos
* that describe post-scan/join processing steps, such as aggregation.
* Many of the fields in these RelOptInfos are meaningless, but their Path
* fields always hold Paths showing ways to do that processing step.
*
* Lastly, there is a RelOptKind for "dead" relations, which are base rels
* that we have proven we don't need to join after all.
*
* Parts of this data structure are specific to various scan and join
* mechanisms. It didn't seem worth creating new node types for them.
*
* relids - Set of base-relation identifiers; it is a base relation
* if there is just one, a join relation if more than one
* rows - estimated number of tuples in the relation after restriction
* clauses have been applied (ie, output rows of a plan for it)
* consider_startup - true if there is any value in keeping plain paths for
* this rel on the basis of having cheap startup cost
* consider_param_startup - the same for parameterized paths
* reltarget - Default Path output tlist for this rel; normally contains
* Var and PlaceHolderVar nodes for the values we need to
* output from this relation.
* List is in no particular order, but all rels of an
* appendrel set must use corresponding orders.
* NOTE: in an appendrel child relation, may contain
* arbitrary expressions pulled up from a subquery!
* pathlist - List of Path nodes, one for each potentially useful
* method of generating the relation
* ppilist - ParamPathInfo nodes for parameterized Paths, if any
* cheapest_startup_path - the pathlist member with lowest startup cost
* (regardless of ordering) among the unparameterized paths;
* or NULL if there is no unparameterized path
* cheapest_total_path - the pathlist member with lowest total cost
* (regardless of ordering) among the unparameterized paths;
* or if there is no unparameterized path, the path with lowest
* total cost among the paths with minimum parameterization
* cheapest_unique_path - for caching cheapest path to produce unique
* (no duplicates) output from relation; NULL if not yet requested
* cheapest_parameterized_paths - best paths for their parameterizations;
* always includes cheapest_total_path, even if that's unparameterized
* direct_lateral_relids - rels this rel has direct LATERAL references to
* lateral_relids - required outer rels for LATERAL, as a Relids set
* (includes both direct and indirect lateral references)
*
* If the relation is a base relation it will have these fields set:
*
* relid - RTE index (this is redundant with the relids field, but
* is provided for convenience of access)
* rtekind - distinguishes plain relation, subquery, or function RTE
* min_attr, max_attr - range of valid AttrNumbers for rel
* attr_needed - array of bitmapsets indicating the highest joinrel
* in which each attribute is needed; if bit 0 is set then
* the attribute is needed as part of final targetlist
* attr_widths - cache space for per-attribute width estimates;
* zero means not computed yet
* lateral_vars - lateral cross-references of rel, if any (list of
* Vars and PlaceHolderVars)
* lateral_referencers - relids of rels that reference this one laterally
* (includes both direct and indirect lateral references)
* indexlist - list of IndexOptInfo nodes for relation's indexes
* (always NIL if it's not a table)
* pages - number of disk pages in relation (zero if not a table)
* tuples - number of tuples in relation (not considering restrictions)
* allvisfrac - fraction of disk pages that are marked all-visible
* subroot - PlannerInfo for subquery (NULL if it's not a subquery)
* subplan_params - list of PlannerParamItems to be passed to subquery
*
* Note: for a subquery, tuples and subroot are not set immediately
* upon creation of the RelOptInfo object; they are filled in when
* set_subquery_pathlist processes the object.
*
* For otherrels that are appendrel members, these fields are filled
* in just as for a baserel, except we don't bother with lateral_vars.
*
* If the relation is either a foreign table or a join of foreign tables that
* all belong to the same foreign server and are assigned to the same user to
* check access permissions as (cf checkAsUser), these fields will be set:
*
* serverid - OID of foreign server, if foreign table (else InvalidOid)
* userid - OID of user to check access as (InvalidOid means current user)
* useridiscurrent - we've assumed that userid equals current user
* fdwroutine - function hooks for FDW, if foreign table (else NULL)
* fdw_private - private state for FDW, if foreign table (else NULL)
*
* The presence of the remaining fields depends on the restrictions
* and joins that the relation participates in:
*
* baserestrictinfo - List of RestrictInfo nodes, containing info about
* each non-join qualification clause in which this relation
* participates (only used for base rels)
* baserestrictcost - Estimated cost of evaluating the baserestrictinfo
* clauses at a single tuple (only used for base rels)
* joininfo - List of RestrictInfo nodes, containing info about each
* join clause in which this relation participates (but
* note this excludes clauses that might be derivable from
* EquivalenceClasses)
* has_eclass_joins - flag that EquivalenceClass joins are possible
*
* Note: Keeping a restrictinfo list in the RelOptInfo is useful only for
* base rels, because for a join rel the set of clauses that are treated as
* restrict clauses varies depending on which sub-relations we choose to join.
* (For example, in a 3-base-rel join, a clause relating rels 1 and 2 must be
* treated as a restrictclause if we join {1} and {2 3} to make {1 2 3}; but
* if we join {1 2} and {3} then that clause will be a restrictclause in {1 2}
* and should not be processed again at the level of {1 2 3}.) Therefore,
* the restrictinfo list in the join case appears in individual JoinPaths
* (field joinrestrictinfo), not in the parent relation. But it's OK for
* the RelOptInfo to store the joininfo list, because that is the same
* for a given rel no matter how we form it.
*
* We store baserestrictcost in the RelOptInfo (for base relations) because
* we know we will need it at least once (to price the sequential scan)
* and may need it multiple times to price index scans.
*----------
*/
typedef enum RelOptKind
{
RELOPT_BASEREL,
RELOPT_JOINREL,
RELOPT_OTHER_MEMBER_REL,
RELOPT_UPPER_REL,
RELOPT_DEADREL
} RelOptKind;
typedef struct RelOptInfo
{
NodeTag type;
RelOptKind reloptkind;
/* all relations included in this RelOptInfo */
Relids relids; /* set of base relids (rangetable indexes) */
/* size estimates generated by planner */
double rows; /* estimated number of result tuples */
/* per-relation planner control flags */
bool consider_startup; /* keep cheap-startup-cost paths? */
bool consider_param_startup; /* ditto, for parameterized paths? */
bool consider_parallel; /* consider parallel paths? */
/* default result targetlist for Paths scanning this relation */
struct PathTarget *reltarget; /* list of Vars/Exprs, cost, width */
/* materialization information */
List *pathlist; /* Path structures */
List *ppilist; /* ParamPathInfos used in pathlist */
List *partial_pathlist; /* partial Paths */
struct Path *cheapest_startup_path;
struct Path *cheapest_total_path;
struct Path *cheapest_unique_path;
List *cheapest_parameterized_paths;
/* parameterization information needed for both base rels and join rels */
/* (see also lateral_vars and lateral_referencers) */
Relids direct_lateral_relids; /* rels directly laterally referenced */
Relids lateral_relids; /* minimum parameterization of rel */
/* information about a base rel (not set for join rels!) */
Index relid;
Oid reltablespace; /* containing tablespace */
RTEKind rtekind; /* RELATION, SUBQUERY, or FUNCTION */
AttrNumber min_attr; /* smallest attrno of rel (often <0) */
AttrNumber max_attr; /* largest attrno of rel */
Relids *attr_needed; /* array indexed [min_attr .. max_attr] */
int32 *attr_widths; /* array indexed [min_attr .. max_attr] */
List *lateral_vars; /* LATERAL Vars and PHVs referenced by rel */
Relids lateral_referencers; /* rels that reference me laterally */
List *indexlist; /* list of IndexOptInfo */
BlockNumber pages; /* size estimates derived from pg_class */
double tuples;
double allvisfrac;
PlannerInfo *subroot; /* if subquery */
List *subplan_params; /* if subquery */
int rel_parallel_workers; /* wanted number of parallel workers */
/* Information about foreign tables and foreign joins */
Oid serverid; /* identifies server for the table or join */
Oid userid; /* identifies user to check access as */
bool useridiscurrent; /* join is only valid for current user */
/* use "struct FdwRoutine" to avoid including fdwapi.h here */
struct FdwRoutine *fdwroutine;
void *fdw_private;
/* used by various scans and joins: */
List *baserestrictinfo; /* RestrictInfo structures (if base
* rel) */
QualCost baserestrictcost; /* cost of evaluating the above */
List *joininfo; /* RestrictInfo structures for join clauses
* involving this rel */
bool has_eclass_joins; /* T means joininfo is incomplete */
} RelOptInfo;
/*
* IndexOptInfo
* Per-index information for planning/optimization
*
* indexkeys[], indexcollations[], opfamily[], and opcintype[]
* each have ncolumns entries.
*
* sortopfamily[], reverse_sort[], and nulls_first[] likewise have
* ncolumns entries, if the index is ordered; but if it is unordered,
* those pointers are NULL.
*
* Zeroes in the indexkeys[] array indicate index columns that are
* expressions; there is one element in indexprs for each such column.
*
* For an ordered index, reverse_sort[] and nulls_first[] describe the
* sort ordering of a forward indexscan; we can also consider a backward
* indexscan, which will generate the reverse ordering.
*
* The indexprs and indpred expressions have been run through
* prepqual.c and eval_const_expressions() for ease of matching to
* WHERE clauses. indpred is in implicit-AND form.
*
* indextlist is a TargetEntry list representing the index columns.
* It provides an equivalent base-relation Var for each simple column,
* and links to the matching indexprs element for each expression column.
*
* While most of these fields are filled when the IndexOptInfo is created
* (by plancat.c), indrestrictinfo and predOK are set later, in
* check_index_predicates().
*/
typedef struct IndexOptInfo
{
NodeTag type;
Oid indexoid; /* OID of the index relation */
Oid reltablespace; /* tablespace of index (not table) */
RelOptInfo *rel; /* back-link to index's table */
/* index-size statistics (from pg_class and elsewhere) */
BlockNumber pages; /* number of disk pages in index */
double tuples; /* number of index tuples in index */
int tree_height; /* index tree height, or -1 if unknown */
/* index descriptor information */
int ncolumns; /* number of columns in index */
int *indexkeys; /* column numbers of index's keys, or 0 */
Oid *indexcollations; /* OIDs of collations of index columns */
Oid *opfamily; /* OIDs of operator families for columns */
Oid *opcintype; /* OIDs of opclass declared input data types */
Oid *sortopfamily; /* OIDs of btree opfamilies, if orderable */
bool *reverse_sort; /* is sort order descending? */
bool *nulls_first; /* do NULLs come first in the sort order? */
bool *canreturn; /* which index cols can be returned in an
* index-only scan? */
Oid relam; /* OID of the access method (in pg_am) */
List *indexprs; /* expressions for non-simple index columns */
List *indpred; /* predicate if a partial index, else NIL */
List *indextlist; /* targetlist representing index columns */
List *indrestrictinfo;/* parent relation's baserestrictinfo list,
* less any conditions implied by the index's
* predicate (unless it's a target rel, see
* comments in check_index_predicates()) */
bool predOK; /* true if index predicate matches query */
bool unique; /* true if a unique index */
bool immediate; /* is uniqueness enforced immediately? */
bool hypothetical; /* true if index doesn't really exist */
/* Remaining fields are copied from the index AM's API struct: */
bool amcanorderbyop; /* does AM support order by operator result? */
bool amoptionalkey; /* can query omit key for the first column? */
bool amsearcharray; /* can AM handle ScalarArrayOpExpr quals? */
bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */
bool amhasgettuple; /* does AM have amgettuple interface? */
bool amhasgetbitmap; /* does AM have amgetbitmap interface? */
bool amcanmarkpos; /* does AM support mark/restore? */
/* Rather than include amapi.h here, we declare amcostestimate like this */
void (*amcostestimate) (); /* AM's cost estimator */
} IndexOptInfo;
/*
* ForeignKeyOptInfo
* Per-foreign-key information for planning/optimization
*
* The per-FK-column arrays can be fixed-size because we allow at most
* INDEX_MAX_KEYS columns in a foreign key constraint. Each array has
* nkeys valid entries.
*/
typedef struct ForeignKeyOptInfo
{
NodeTag type;
/* Basic data about the foreign key (fetched from catalogs): */
Index con_relid; /* RT index of the referencing table */
Index ref_relid; /* RT index of the referenced table */
int nkeys; /* number of columns in the foreign key */
AttrNumber conkey[INDEX_MAX_KEYS]; /* cols in referencing table */
AttrNumber confkey[INDEX_MAX_KEYS]; /* cols in referenced table */
Oid conpfeqop[INDEX_MAX_KEYS]; /* PK = FK operator OIDs */
/* Derived info about whether FK's equality conditions match the query: */
int nmatched_ec; /* # of FK cols matched by ECs */
int nmatched_rcols; /* # of FK cols matched by non-EC rinfos */
int nmatched_ri; /* total # of non-EC rinfos matched to FK */
/* Pointer to eclass matching each column's condition, if there is one */
struct EquivalenceClass *eclass[INDEX_MAX_KEYS];
/* List of non-EC RestrictInfos matching each column's condition */
List *rinfos[INDEX_MAX_KEYS];
} ForeignKeyOptInfo;
/*
* EquivalenceClasses
*
* Whenever we can determine that a mergejoinable equality clause A = B is
* not delayed by any outer join, we create an EquivalenceClass containing
* the expressions A and B to record this knowledge. If we later find another
* equivalence B = C, we add C to the existing EquivalenceClass; this may
* require merging two existing EquivalenceClasses. At the end of the qual
* distribution process, we have sets of values that are known all transitively
* equal to each other, where "equal" is according to the rules of the btree
* operator family(s) shown in ec_opfamilies, as well as the collation shown
* by ec_collation. (We restrict an EC to contain only equalities whose
* operators belong to the same set of opfamilies. This could probably be
* relaxed, but for now it's not worth the trouble, since nearly all equality
* operators belong to only one btree opclass anyway. Similarly, we suppose
* that all or none of the input datatypes are collatable, so that a single
* collation value is sufficient.)
*
* We also use EquivalenceClasses as the base structure for PathKeys, letting
* us represent knowledge about different sort orderings being equivalent.
* Since every PathKey must reference an EquivalenceClass, we will end up
* with single-member EquivalenceClasses whenever a sort key expression has
* not been equivalenced to anything else. It is also possible that such an
* EquivalenceClass will contain a volatile expression ("ORDER BY random()"),
* which is a case that can't arise otherwise since clauses containing
* volatile functions are never considered mergejoinable. We mark such
* EquivalenceClasses specially to prevent them from being merged with
* ordinary EquivalenceClasses. Also, for volatile expressions we have
* to be careful to match the EquivalenceClass to the correct targetlist
* entry: consider SELECT random() AS a, random() AS b ... ORDER BY b,a.
* So we record the SortGroupRef of the originating sort clause.
*
* We allow equality clauses appearing below the nullable side of an outer join
* to form EquivalenceClasses, but these have a slightly different meaning:
* the included values might be all NULL rather than all the same non-null
* values. See src/backend/optimizer/README for more on that point.
*
* NB: if ec_merged isn't NULL, this class has been merged into another, and
* should be ignored in favor of using the pointed-to class.
*/
typedef struct EquivalenceClass
{
NodeTag type;
List *ec_opfamilies; /* btree operator family OIDs */
Oid ec_collation; /* collation, if datatypes are collatable */
List *ec_members; /* list of EquivalenceMembers */
List *ec_sources; /* list of generating RestrictInfos */
List *ec_derives; /* list of derived RestrictInfos */
Relids ec_relids; /* all relids appearing in ec_members, except
* for child members (see below) */
bool ec_has_const; /* any pseudoconstants in ec_members? */
bool ec_has_volatile; /* the (sole) member is a volatile expr */
bool ec_below_outer_join; /* equivalence applies below an OJ */
bool ec_broken; /* failed to generate needed clauses? */
Index ec_sortref; /* originating sortclause label, or 0 */
struct EquivalenceClass *ec_merged; /* set if merged into another EC */
} EquivalenceClass;
/*
* If an EC contains a const and isn't below-outer-join, any PathKey depending
* on it must be redundant, since there's only one possible value of the key.
*/
#define EC_MUST_BE_REDUNDANT(eclass) \
((eclass)->ec_has_const && !(eclass)->ec_below_outer_join)
/*
* EquivalenceMember - one member expression of an EquivalenceClass
*
* em_is_child signifies that this element was built by transposing a member
* for an appendrel parent relation to represent the corresponding expression
* for an appendrel child. These members are used for determining the
* pathkeys of scans on the child relation and for explicitly sorting the
* child when necessary to build a MergeAppend path for the whole appendrel
* tree. An em_is_child member has no impact on the properties of the EC as a
* whole; in particular the EC's ec_relids field does NOT include the child
* relation. An em_is_child member should never be marked em_is_const nor
* cause ec_has_const or ec_has_volatile to be set, either. Thus, em_is_child
* members are not really full-fledged members of the EC, but just reflections
* or doppelgangers of real members. Most operations on EquivalenceClasses
* should ignore em_is_child members, and those that don't should test
* em_relids to make sure they only consider relevant members.
*
* em_datatype is usually the same as exprType(em_expr), but can be
* different when dealing with a binary-compatible opfamily; in particular
* anyarray_ops would never work without this. Use em_datatype when
* looking up a specific btree operator to work with this expression.
*/
typedef struct EquivalenceMember
{
NodeTag type;
Expr *em_expr; /* the expression represented */
Relids em_relids; /* all relids appearing in em_expr */
Relids em_nullable_relids; /* nullable by lower outer joins */
bool em_is_const; /* expression is pseudoconstant? */
bool em_is_child; /* derived version for a child relation? */
Oid em_datatype; /* the "nominal type" used by the opfamily */
} EquivalenceMember;
/*
* PathKeys
*
* The sort ordering of a path is represented by a list of PathKey nodes.
* An empty list implies no known ordering. Otherwise the first item
* represents the primary sort key, the second the first secondary sort key,
* etc. The value being sorted is represented by linking to an
* EquivalenceClass containing that value and including pk_opfamily among its
* ec_opfamilies. The EquivalenceClass tells which collation to use, too.
* This is a convenient method because it makes it trivial to detect
* equivalent and closely-related orderings. (See optimizer/README for more
* information.)
*
* Note: pk_strategy is either BTLessStrategyNumber (for ASC) or
* BTGreaterStrategyNumber (for DESC). We assume that all ordering-capable
* index types will use btree-compatible strategy numbers.
*/
typedef struct PathKey
{
NodeTag type;
EquivalenceClass *pk_eclass; /* the value that is ordered */
Oid pk_opfamily; /* btree opfamily defining the ordering */
int pk_strategy; /* sort direction (ASC or DESC) */
bool pk_nulls_first; /* do NULLs come before normal values? */
} PathKey;
/*
* PathTarget
*
* This struct contains what we need to know during planning about the
* targetlist (output columns) that a Path will compute. Each RelOptInfo
* includes a default PathTarget, which its individual Paths may simply
* reference. However, in some cases a Path may compute outputs different
* from other Paths, and in that case we make a custom PathTarget for it.
* For example, an indexscan might return index expressions that would
* otherwise need to be explicitly calculated. (Note also that "upper"
* relations generally don't have useful default PathTargets.)
*
* exprs contains bare expressions; they do not have TargetEntry nodes on top,
* though those will appear in finished Plans.
*
* sortgrouprefs[] is an array of the same length as exprs, containing the
* corresponding sort/group refnos, or zeroes for expressions not referenced
* by sort/group clauses. If sortgrouprefs is NULL (which it generally is in
* RelOptInfo.reltarget targets; only upper-level Paths contain this info),
* we have not identified sort/group columns in this tlist. This allows us to
* deal with sort/group refnos when needed with less expense than including
* TargetEntry nodes in the exprs list.
*/
typedef struct PathTarget
{
NodeTag type;
List *exprs; /* list of expressions to be computed */
Index *sortgrouprefs; /* corresponding sort/group refnos, or 0 */
QualCost cost; /* cost of evaluating the expressions */
int width; /* estimated avg width of result tuples */
} PathTarget;
/* Convenience macro to get a sort/group refno from a PathTarget */
#define get_pathtarget_sortgroupref(target, colno) \
((target)->sortgrouprefs ? (target)->sortgrouprefs[colno] : (Index) 0)
/*
* ParamPathInfo
*
* All parameterized paths for a given relation with given required outer rels
* link to a single ParamPathInfo, which stores common information such as
* the estimated rowcount for this parameterization. We do this partly to
* avoid recalculations, but mostly to ensure that the estimated rowcount
* is in fact the same for every such path.
*
* Note: ppi_clauses is only used in ParamPathInfos for base relation paths;
* in join cases it's NIL because the set of relevant clauses varies depending
* on how the join is formed. The relevant clauses will appear in each
* parameterized join path's joinrestrictinfo list, instead.
*/
typedef struct ParamPathInfo
{
NodeTag type;
Relids ppi_req_outer; /* rels supplying parameters used by path */
double ppi_rows; /* estimated number of result tuples */
List *ppi_clauses; /* join clauses available from outer rels */
} ParamPathInfo;
/*
* Type "Path" is used as-is for sequential-scan paths, as well as some other
* simple plan types that we don't need any extra information in the path for.
* For other path types it is the first component of a larger struct.
*
* "pathtype" is the NodeTag of the Plan node we could build from this Path.
* It is partially redundant with the Path's NodeTag, but allows us to use
* the same Path type for multiple Plan types when there is no need to
* distinguish the Plan type during path processing.
*
* "parent" identifies the relation this Path scans, and "pathtarget"
* describes the precise set of output columns the Path would compute.
* In simple cases all Paths for a given rel share the same targetlist,
* which we represent by having path->pathtarget equal to parent->reltarget.
*
* "param_info", if not NULL, links to a ParamPathInfo that identifies outer
* relation(s) that provide parameter values to each scan of this path.
* That means this path can only be joined to those rels by means of nestloop
* joins with this path on the inside. Also note that a parameterized path
* is responsible for testing all "movable" joinclauses involving this rel
* and the specified outer rel(s).
*
* "rows" is the same as parent->rows in simple paths, but in parameterized
* paths and UniquePaths it can be less than parent->rows, reflecting the
* fact that we've filtered by extra join conditions or removed duplicates.
*
* "pathkeys" is a List of PathKey nodes (see above), describing the sort
* ordering of the path's output rows.
*/
typedef struct Path
{
NodeTag type;
NodeTag pathtype; /* tag identifying scan/join method */
RelOptInfo *parent; /* the relation this path can build */
PathTarget *pathtarget; /* list of Vars/Exprs, cost, width */
ParamPathInfo *param_info; /* parameterization info, or NULL if none */
bool parallel_aware; /* engage parallel-aware logic? */
bool parallel_safe; /* OK to use as part of parallel plan? */
int parallel_workers; /* desired # of workers; 0 = not
* parallel */
/* estimated size/costs for path (see costsize.c for more info) */
double rows; /* estimated number of result tuples */
Cost startup_cost; /* cost expended before fetching any tuples */
Cost total_cost; /* total cost (assuming all tuples fetched) */
List *pathkeys; /* sort ordering of path's output */
/* pathkeys is a List of PathKey nodes; see above */
} Path;
/* Macro for extracting a path's parameterization relids; beware double eval */
#define PATH_REQ_OUTER(path) \
((path)->param_info ? (path)->param_info->ppi_req_outer : (Relids) NULL)
/*----------
* IndexPath represents an index scan over a single index.
*
* This struct is used for both regular indexscans and index-only scans;
* path.pathtype is T_IndexScan or T_IndexOnlyScan to show which is meant.
*
* 'indexinfo' is the index to be scanned.
*
* 'indexclauses' is a list of index qualification clauses, with implicit
* AND semantics across the list. Each clause is a RestrictInfo node from
* the query's WHERE or JOIN conditions. An empty list implies a full
* index scan.
*
* 'indexquals' has the same structure as 'indexclauses', but it contains
* the actual index qual conditions that can be used with the index.
* In simple cases this is identical to 'indexclauses', but when special
* indexable operators appear in 'indexclauses', they are replaced by the
* derived indexscannable conditions in 'indexquals'.
*
* 'indexqualcols' is an integer list of index column numbers (zero-based)
* of the same length as 'indexquals', showing which index column each qual
* is meant to be used with. 'indexquals' is required to be ordered by
* index column, so 'indexqualcols' must form a nondecreasing sequence.
* (The order of multiple quals for the same index column is unspecified.)
*
* 'indexorderbys', if not NIL, is a list of ORDER BY expressions that have
* been found to be usable as ordering operators for an amcanorderbyop index.
* The list must match the path's pathkeys, ie, one expression per pathkey
* in the same order. These are not RestrictInfos, just bare expressions,
* since they generally won't yield booleans. Also, unlike the case for
* quals, it's guaranteed that each expression has the index key on the left
* side of the operator.
*
* 'indexorderbycols' is an integer list of index column numbers (zero-based)
* of the same length as 'indexorderbys', showing which index column each
* ORDER BY expression is meant to be used with. (There is no restriction
* on which index column each ORDER BY can be used with.)
*
* 'indexscandir' is one of:
* ForwardScanDirection: forward scan of an ordered index
* BackwardScanDirection: backward scan of an ordered index
* NoMovementScanDirection: scan of an unordered index, or don't care
* (The executor doesn't care whether it gets ForwardScanDirection or
* NoMovementScanDirection for an indexscan, but the planner wants to
* distinguish ordered from unordered indexes for building pathkeys.)
*
* 'indextotalcost' and 'indexselectivity' are saved in the IndexPath so that
* we need not recompute them when considering using the same index in a
* bitmap index/heap scan (see BitmapHeapPath). The costs of the IndexPath
* itself represent the costs of an IndexScan or IndexOnlyScan plan type.
*----------
*/
typedef struct IndexPath
{
Path path;
IndexOptInfo *indexinfo;
List *indexclauses;
List *indexquals;
List *indexqualcols;
List *indexorderbys;
List *indexorderbycols;
ScanDirection indexscandir;
Cost indextotalcost;
Selectivity indexselectivity;
} IndexPath;
/*
* BitmapHeapPath represents one or more indexscans that generate TID bitmaps
* instead of directly accessing the heap, followed by AND/OR combinations
* to produce a single bitmap, followed by a heap scan that uses the bitmap.
* Note that the output is always considered unordered, since it will come
* out in physical heap order no matter what the underlying indexes did.
*
* The individual indexscans are represented by IndexPath nodes, and any
* logic on top of them is represented by a tree of BitmapAndPath and
* BitmapOrPath nodes. Notice that we can use the same IndexPath node both
* to represent a regular (or index-only) index scan plan, and as the child
* of a BitmapHeapPath that represents scanning the same index using a
* BitmapIndexScan. The startup_cost and total_cost figures of an IndexPath
* always represent the costs to use it as a regular (or index-only)
* IndexScan. The costs of a BitmapIndexScan can be computed using the
* IndexPath's indextotalcost and indexselectivity.
*/
typedef struct BitmapHeapPath
{
Path path;
Path *bitmapqual; /* IndexPath, BitmapAndPath, BitmapOrPath */
} BitmapHeapPath;
/*
* BitmapAndPath represents a BitmapAnd plan node; it can only appear as
* part of the substructure of a BitmapHeapPath. The Path structure is
* a bit more heavyweight than we really need for this, but for simplicity
* we make it a derivative of Path anyway.
*/
typedef struct BitmapAndPath
{
Path path;
List *bitmapquals; /* IndexPaths and BitmapOrPaths */
Selectivity bitmapselectivity;
} BitmapAndPath;
/*
* BitmapOrPath represents a BitmapOr plan node; it can only appear as
* part of the substructure of a BitmapHeapPath. The Path structure is
* a bit more heavyweight than we really need for this, but for simplicity
* we make it a derivative of Path anyway.
*/
typedef struct BitmapOrPath
{
Path path;
List *bitmapquals; /* IndexPaths and BitmapAndPaths */
Selectivity bitmapselectivity;
} BitmapOrPath;
/*
* TidPath represents a scan by TID
*
* tidquals is an implicitly OR'ed list of qual expressions of the form
* "CTID = pseudoconstant" or "CTID = ANY(pseudoconstant_array)".
* Note they are bare expressions, not RestrictInfos.
*/
typedef struct TidPath
{
Path path;
List *tidquals; /* qual(s) involving CTID = something */
} TidPath;
/*
* SubqueryScanPath represents a scan of an unflattened subquery-in-FROM
*
* Note that the subpath comes from a different planning domain; for example
* RTE indexes within it mean something different from those known to the
* SubqueryScanPath. path.parent->subroot is the planning context needed to
* interpret the subpath.
*/
typedef struct SubqueryScanPath
{
Path path;
Path *subpath; /* path representing subquery execution */
} SubqueryScanPath;
/*
* ForeignPath represents a potential scan of a foreign table, foreign join
* or foreign upper-relation.
*
* fdw_private stores FDW private data about the scan. While fdw_private is
* not actually touched by the core code during normal operations, it's
* generally a good idea to use a representation that can be dumped by
* nodeToString(), so that you can examine the structure during debugging
* with tools like pprint().
*/
typedef struct ForeignPath
{
Path path;
Path *fdw_outerpath;
List *fdw_private;
} ForeignPath;
/*
* CustomPath represents a table scan done by some out-of-core extension.
*
* We provide a set of hooks here - which the provider must take care to set
* up correctly - to allow extensions to supply their own methods of scanning
* a relation. For example, a provider might provide GPU acceleration, a
* cache-based scan, or some other kind of logic we haven't dreamed up yet.
*
* CustomPaths can be injected into the planning process for a relation by
* set_rel_pathlist_hook functions.
*
* Core code must avoid assuming that the CustomPath is only as large as
* the structure declared here; providers are allowed to make it the first
* element in a larger structure. (Since the planner never copies Paths,
* this doesn't add any complication.) However, for consistency with the
* FDW case, we provide a "custom_private" field in CustomPath; providers
* may prefer to use that rather than define another struct type.
*/
struct CustomPathMethods;
typedef struct CustomPath
{
Path path;
uint32 flags; /* mask of CUSTOMPATH_* flags, see
* nodes/extensible.h */
List *custom_paths; /* list of child Path nodes, if any */
List *custom_private;
const struct CustomPathMethods *methods;
} CustomPath;
/*
* AppendPath represents an Append plan, ie, successive execution of
* several member plans.
*
* Note: it is possible for "subpaths" to contain only one, or even no,
* elements. These cases are optimized during create_append_plan.
* In particular, an AppendPath with no subpaths is a "dummy" path that
* is created to represent the case that a relation is provably empty.
*/
typedef struct AppendPath
{
Path path;
List *subpaths; /* list of component Paths */
} AppendPath;
#define IS_DUMMY_PATH(p) \
(IsA((p), AppendPath) && ((AppendPath *) (p))->subpaths == NIL)
/* A relation that's been proven empty will have one path that is dummy */
#define IS_DUMMY_REL(r) \
((r)->cheapest_total_path != NULL && \
IS_DUMMY_PATH((r)->cheapest_total_path))
/*
* MergeAppendPath represents a MergeAppend plan, ie, the merging of sorted
* results from several member plans to produce similarly-sorted output.
*/
typedef struct MergeAppendPath
{
Path path;
List *subpaths; /* list of component Paths */
double limit_tuples; /* hard limit on output tuples, or -1 */
} MergeAppendPath;
/*
* ResultPath represents use of a Result plan node to compute a variable-free
* targetlist with no underlying tables (a "SELECT expressions" query).
* The query could have a WHERE clause, too, represented by "quals".
*
* Note that quals is a list of bare clauses, not RestrictInfos.
*/
typedef struct ResultPath
{
Path path;
List *quals;
} ResultPath;
/*
* MaterialPath represents use of a Material plan node, i.e., caching of
* the output of its subpath. This is used when the subpath is expensive
* and needs to be scanned repeatedly, or when we need mark/restore ability
* and the subpath doesn't have it.
*/
typedef struct MaterialPath
{
Path path;
Path *subpath;
} MaterialPath;
/*
* UniquePath represents elimination of distinct rows from the output of
* its subpath.
*
* This can represent significantly different plans: either hash-based or
* sort-based implementation, or a no-op if the input path can be proven
* distinct already. The decision is sufficiently localized that it's not
* worth having separate Path node types. (Note: in the no-op case, we could
* eliminate the UniquePath node entirely and just return the subpath; but
* it's convenient to have a UniquePath in the path tree to signal upper-level
* routines that the input is known distinct.)
*/
typedef enum
{
UNIQUE_PATH_NOOP, /* input is known unique already */
UNIQUE_PATH_HASH, /* use hashing */
UNIQUE_PATH_SORT /* use sorting */
} UniquePathMethod;
typedef struct UniquePath
{
Path path;
Path *subpath;
UniquePathMethod umethod;
List *in_operators; /* equality operators of the IN clause */
List *uniq_exprs; /* expressions to be made unique */
} UniquePath;
/*
* GatherPath runs several copies of a plan in parallel and collects the
* results. The parallel leader may also execute the plan, unless the
* single_copy flag is set.
*/
typedef struct GatherPath
{
Path path;
Path *subpath; /* path for each worker */
bool single_copy; /* path must not be executed >1x */
int num_workers; /* number of workers sought to help */
} GatherPath;
/*
* All join-type paths share these fields.
*/
typedef struct JoinPath
{
Path path;
JoinType jointype;
Path *outerjoinpath; /* path for the outer side of the join */
Path *innerjoinpath; /* path for the inner side of the join */
List *joinrestrictinfo; /* RestrictInfos to apply to join */
/*
* See the notes for RelOptInfo and ParamPathInfo to understand why
* joinrestrictinfo is needed in JoinPath, and can't be merged into the
* parent RelOptInfo.
*/
} JoinPath;
/*
* A nested-loop path needs no special fields.
*/
typedef JoinPath NestPath;
/*
* A mergejoin path has these fields.
*
* Unlike other path types, a MergePath node doesn't represent just a single
* run-time plan node: it can represent up to four. Aside from the MergeJoin
* node itself, there can be a Sort node for the outer input, a Sort node
* for the inner input, and/or a Material node for the inner input. We could
* represent these nodes by separate path nodes, but considering how many
* different merge paths are investigated during a complex join problem,
* it seems better to avoid unnecessary palloc overhead.
*
* path_mergeclauses lists the clauses (in the form of RestrictInfos)
* that will be used in the merge.
*
* Note that the mergeclauses are a subset of the parent relation's
* restriction-clause list. Any join clauses that are not mergejoinable
* appear only in the parent's restrict list, and must be checked by a
* qpqual at execution time.
*
* outersortkeys (resp. innersortkeys) is NIL if the outer path
* (resp. inner path) is already ordered appropriately for the
* mergejoin. If it is not NIL then it is a PathKeys list describing
* the ordering that must be created by an explicit Sort node.
*
* materialize_inner is TRUE if a Material node should be placed atop the
* inner input. This may appear with or without an inner Sort step.
*/
typedef struct MergePath
{
JoinPath jpath;
List *path_mergeclauses; /* join clauses to be used for merge */
List *outersortkeys; /* keys for explicit sort, if any */
List *innersortkeys; /* keys for explicit sort, if any */
bool materialize_inner; /* add Materialize to inner? */
} MergePath;
/*
* A hashjoin path has these fields.
*
* The remarks above for mergeclauses apply for hashclauses as well.
*
* Hashjoin does not care what order its inputs appear in, so we have
* no need for sortkeys.
*/
typedef struct HashPath
{
JoinPath jpath;
List *path_hashclauses; /* join clauses used for hashing */
int num_batches; /* number of batches expected */
} HashPath;
/*
* ProjectionPath represents a projection (that is, targetlist computation)
*
* Nominally, this path node represents using a Result plan node to do a
* projection step. However, if the input plan node supports projection,
* we can just modify its output targetlist to do the required calculations
* directly, and not need a Result. In some places in the planner we can just
* jam the desired PathTarget into the input path node (and adjust its cost
* accordingly), so we don't need a ProjectionPath. But in other places
* it's necessary to not modify the input path node, so we need a separate
* ProjectionPath node, which is marked dummy to indicate that we intend to
* assign the work to the input plan node. The estimated cost for the
* ProjectionPath node will account for whether a Result will be used or not.
*/
typedef struct ProjectionPath
{
Path path;
Path *subpath; /* path representing input source */
bool dummypp; /* true if no separate Result is needed */
} ProjectionPath;
/*
* SortPath represents an explicit sort step
*
* The sort keys are, by definition, the same as path.pathkeys.
*
* Note: the Sort plan node cannot project, so path.pathtarget must be the
* same as the input's pathtarget.
*/
typedef struct SortPath
{
Path path;
Path *subpath; /* path representing input source */
} SortPath;
/*
* GroupPath represents grouping (of presorted input)
*
* groupClause represents the columns to be grouped on; the input path
* must be at least that well sorted.
*
* We can also apply a qual to the grouped rows (equivalent of HAVING)
*/
typedef struct GroupPath
{
Path path;
Path *subpath; /* path representing input source */
List *groupClause; /* a list of SortGroupClause's */
List *qual; /* quals (HAVING quals), if any */
} GroupPath;
/*
* UpperUniquePath represents adjacent-duplicate removal (in presorted input)
*
* The columns to be compared are the first numkeys columns of the path's
* pathkeys. The input is presumed already sorted that way.
*/
typedef struct UpperUniquePath
{
Path path;
Path *subpath; /* path representing input source */
int numkeys; /* number of pathkey columns to compare */
} UpperUniquePath;
/*
* AggPath represents generic computation of aggregate functions
*
* This may involve plain grouping (but not grouping sets), using either
* sorted or hashed grouping; for the AGG_SORTED case, the input must be
* appropriately presorted.
*/
typedef struct AggPath
{
Path path;
Path *subpath; /* path representing input source */
AggStrategy aggstrategy; /* basic strategy, see nodes.h */
AggSplit aggsplit; /* agg-splitting mode, see nodes.h */
double numGroups; /* estimated number of groups in input */
List *groupClause; /* a list of SortGroupClause's */
List *qual; /* quals (HAVING quals), if any */
} AggPath;
/*
* GroupingSetsPath represents a GROUPING SETS aggregation
*
* Currently we only support this in sorted not hashed form, so the input
* must always be appropriately presorted.
*/
typedef struct GroupingSetsPath
{
Path path;
Path *subpath; /* path representing input source */
List *rollup_groupclauses; /* list of lists of SortGroupClause's */
List *rollup_lists; /* parallel list of lists of grouping sets */
List *qual; /* quals (HAVING quals), if any */
} GroupingSetsPath;
/*
* MinMaxAggPath represents computation of MIN/MAX aggregates from indexes
*/
typedef struct MinMaxAggPath
{
Path path;
List *mmaggregates; /* list of MinMaxAggInfo */
List *quals; /* HAVING quals, if any */
} MinMaxAggPath;
/*
* WindowAggPath represents generic computation of window functions
*
* Note: winpathkeys is separate from path.pathkeys because the actual sort
* order might be an extension of winpathkeys; but createplan.c needs to
* know exactly how many pathkeys match the window clause.
*/
typedef struct WindowAggPath
{
Path path;
Path *subpath; /* path representing input source */
WindowClause *winclause; /* WindowClause we'll be using */
List *winpathkeys; /* PathKeys for PARTITION keys + ORDER keys */
} WindowAggPath;
/*
* SetOpPath represents a set-operation, that is INTERSECT or EXCEPT
*/
typedef struct SetOpPath
{
Path path;
Path *subpath; /* path representing input source */
SetOpCmd cmd; /* what to do, see nodes.h */
SetOpStrategy strategy; /* how to do it, see nodes.h */
List *distinctList; /* SortGroupClauses identifying target cols */
AttrNumber flagColIdx; /* where is the flag column, if any */
int firstFlag; /* flag value for first input relation */
double numGroups; /* estimated number of groups in input */
} SetOpPath;
/*
* RecursiveUnionPath represents a recursive UNION node
*/
typedef struct RecursiveUnionPath
{
Path path;
Path *leftpath; /* paths representing input sources */
Path *rightpath;
List *distinctList; /* SortGroupClauses identifying target cols */
int wtParam; /* ID of Param representing work table */
double numGroups; /* estimated number of groups in input */
} RecursiveUnionPath;
/*
* LockRowsPath represents acquiring row locks for SELECT FOR UPDATE/SHARE
*/
typedef struct LockRowsPath
{
Path path;
Path *subpath; /* path representing input source */
List *rowMarks; /* a list of PlanRowMark's */
int epqParam; /* ID of Param for EvalPlanQual re-eval */
} LockRowsPath;
/*
* ModifyTablePath represents performing INSERT/UPDATE/DELETE modifications
*
* We represent most things that will be in the ModifyTable plan node
* literally, except we have child Path(s) not Plan(s). But analysis of the
* OnConflictExpr is deferred to createplan.c, as is collection of FDW data.
*/
typedef struct ModifyTablePath
{
Path path;
CmdType operation; /* INSERT, UPDATE, or DELETE */
bool canSetTag; /* do we set the command tag/es_processed? */
Index nominalRelation; /* Parent RT index for use of EXPLAIN */
List *resultRelations; /* integer list of RT indexes */
List *subpaths; /* Path(s) producing source data */
List *subroots; /* per-target-table PlannerInfos */
List *withCheckOptionLists; /* per-target-table WCO lists */
List *returningLists; /* per-target-table RETURNING tlists */
List *rowMarks; /* PlanRowMarks (non-locking only) */
OnConflictExpr *onconflict; /* ON CONFLICT clause, or NULL */
int epqParam; /* ID of Param for EvalPlanQual re-eval */
} ModifyTablePath;
/*
* LimitPath represents applying LIMIT/OFFSET restrictions
*/
typedef struct LimitPath
{
Path path;
Path *subpath; /* path representing input source */
Node *limitOffset; /* OFFSET parameter, or NULL if none */
Node *limitCount; /* COUNT parameter, or NULL if none */
} LimitPath;
/*
* Restriction clause info.
*
* We create one of these for each AND sub-clause of a restriction condition
* (WHERE or JOIN/ON clause). Since the restriction clauses are logically
* ANDed, we can use any one of them or any subset of them to filter out
* tuples, without having to evaluate the rest. The RestrictInfo node itself
* stores data used by the optimizer while choosing the best query plan.
*
* If a restriction clause references a single base relation, it will appear
* in the baserestrictinfo list of the RelOptInfo for that base rel.
*
* If a restriction clause references more than one base rel, it will
* appear in the joininfo list of every RelOptInfo that describes a strict
* subset of the base rels mentioned in the clause. The joininfo lists are
* used to drive join tree building by selecting plausible join candidates.
* The clause cannot actually be applied until we have built a join rel
* containing all the base rels it references, however.
*
* When we construct a join rel that includes all the base rels referenced
* in a multi-relation restriction clause, we place that clause into the
* joinrestrictinfo lists of paths for the join rel, if neither left nor
* right sub-path includes all base rels referenced in the clause. The clause
* will be applied at that join level, and will not propagate any further up
* the join tree. (Note: the "predicate migration" code was once intended to
* push restriction clauses up and down the plan tree based on evaluation
* costs, but it's dead code and is unlikely to be resurrected in the
* foreseeable future.)
*
* Note that in the presence of more than two rels, a multi-rel restriction
* might reach different heights in the join tree depending on the join
* sequence we use. So, these clauses cannot be associated directly with
* the join RelOptInfo, but must be kept track of on a per-join-path basis.
*
* RestrictInfos that represent equivalence conditions (i.e., mergejoinable
* equalities that are not outerjoin-delayed) are handled a bit differently.
* Initially we attach them to the EquivalenceClasses that are derived from
* them. When we construct a scan or join path, we look through all the
* EquivalenceClasses and generate derived RestrictInfos representing the
* minimal set of conditions that need to be checked for this particular scan
* or join to enforce that all members of each EquivalenceClass are in fact
* equal in all rows emitted by the scan or join.
*
* When dealing with outer joins we have to be very careful about pushing qual
* clauses up and down the tree. An outer join's own JOIN/ON conditions must
* be evaluated exactly at that join node, unless they are "degenerate"
* conditions that reference only Vars from the nullable side of the join.
* Quals appearing in WHERE or in a JOIN above the outer join cannot be pushed
* down below the outer join, if they reference any nullable Vars.
* RestrictInfo nodes contain a flag to indicate whether a qual has been
* pushed down to a lower level than its original syntactic placement in the
* join tree would suggest. If an outer join prevents us from pushing a qual
* down to its "natural" semantic level (the level associated with just the
* base rels used in the qual) then we mark the qual with a "required_relids"
* value including more than just the base rels it actually uses. By
* pretending that the qual references all the rels required to form the outer
* join, we prevent it from being evaluated below the outer join's joinrel.
* When we do form the outer join's joinrel, we still need to distinguish
* those quals that are actually in that join's JOIN/ON condition from those
* that appeared elsewhere in the tree and were pushed down to the join rel
* because they used no other rels. That's what the is_pushed_down flag is
* for; it tells us that a qual is not an OUTER JOIN qual for the set of base
* rels listed in required_relids. A clause that originally came from WHERE
* or an INNER JOIN condition will *always* have its is_pushed_down flag set.
* It's possible for an OUTER JOIN clause to be marked is_pushed_down too,
* if we decide that it can be pushed down into the nullable side of the join.
* In that case it acts as a plain filter qual for wherever it gets evaluated.
* (In short, is_pushed_down is only false for non-degenerate outer join
* conditions. Possibly we should rename it to reflect that meaning? But
* see also the comments for RINFO_IS_PUSHED_DOWN, below.)
*
* RestrictInfo nodes also contain an outerjoin_delayed flag, which is true
* if the clause's applicability must be delayed due to any outer joins
* appearing below it (ie, it has to be postponed to some join level higher
* than the set of relations it actually references).
*
* There is also an outer_relids field, which is NULL except for outer join
* clauses; for those, it is the set of relids on the outer side of the
* clause's outer join. (These are rels that the clause cannot be applied to
* in parameterized scans, since pushing it into the join's outer side would
* lead to wrong answers.)
*
* There is also a nullable_relids field, which is the set of rels the clause
* references that can be forced null by some outer join below the clause.
*
* outerjoin_delayed = true is subtly different from nullable_relids != NULL:
* a clause might reference some nullable rels and yet not be
* outerjoin_delayed because it also references all the other rels of the
* outer join(s). A clause that is not outerjoin_delayed can be enforced
* anywhere it is computable.
*
* In general, the referenced clause might be arbitrarily complex. The
* kinds of clauses we can handle as indexscan quals, mergejoin clauses,
* or hashjoin clauses are limited (e.g., no volatile functions). The code
* for each kind of path is responsible for identifying the restrict clauses
* it can use and ignoring the rest. Clauses not implemented by an indexscan,
* mergejoin, or hashjoin will be placed in the plan qual or joinqual field
* of the finished Plan node, where they will be enforced by general-purpose
* qual-expression-evaluation code. (But we are still entitled to count
* their selectivity when estimating the result tuple count, if we
* can guess what it is...)
*
* When the referenced clause is an OR clause, we generate a modified copy
* in which additional RestrictInfo nodes are inserted below the top-level
* OR/AND structure. This is a convenience for OR indexscan processing:
* indexquals taken from either the top level or an OR subclause will have
* associated RestrictInfo nodes.
*
* The can_join flag is set true if the clause looks potentially useful as
* a merge or hash join clause, that is if it is a binary opclause with
* nonoverlapping sets of relids referenced in the left and right sides.
* (Whether the operator is actually merge or hash joinable isn't checked,
* however.)
*
* The pseudoconstant flag is set true if the clause contains no Vars of
* the current query level and no volatile functions. Such a clause can be
* pulled out and used as a one-time qual in a gating Result node. We keep
* pseudoconstant clauses in the same lists as other RestrictInfos so that
* the regular clause-pushing machinery can assign them to the correct join
* level, but they need to be treated specially for cost and selectivity
* estimates. Note that a pseudoconstant clause can never be an indexqual
* or merge or hash join clause, so it's of no interest to large parts of
* the planner.
*
* When join clauses are generated from EquivalenceClasses, there may be
* several equally valid ways to enforce join equivalence, of which we need
* apply only one. We mark clauses of this kind by setting parent_ec to
* point to the generating EquivalenceClass. Multiple clauses with the same
* parent_ec in the same join are redundant.
*/
typedef struct RestrictInfo
{
NodeTag type;
Expr *clause; /* the represented clause of WHERE or JOIN */
bool is_pushed_down; /* TRUE if clause was pushed down in level */
bool outerjoin_delayed; /* TRUE if delayed by lower outer join */
bool can_join; /* see comment above */
bool pseudoconstant; /* see comment above */
/* The set of relids (varnos) actually referenced in the clause: */
Relids clause_relids;
/* The set of relids required to evaluate the clause: */
Relids required_relids;
/* If an outer-join clause, the outer-side relations, else NULL: */
Relids outer_relids;
/* The relids used in the clause that are nullable by lower outer joins: */
Relids nullable_relids;
/* These fields are set for any binary opclause: */
Relids left_relids; /* relids in left side of clause */
Relids right_relids; /* relids in right side of clause */
/* This field is NULL unless clause is an OR clause: */
Expr *orclause; /* modified clause with RestrictInfos */
/* This field is NULL unless clause is potentially redundant: */
EquivalenceClass *parent_ec; /* generating EquivalenceClass */
/* cache space for cost and selectivity */
QualCost eval_cost; /* eval cost of clause; -1 if not yet set */
Selectivity norm_selec; /* selectivity for "normal" (JOIN_INNER)
* semantics; -1 if not yet set; >1 means a
* redundant clause */
Selectivity outer_selec; /* selectivity for outer join semantics; -1 if
* not yet set */
/* valid if clause is mergejoinable, else NIL */
List *mergeopfamilies; /* opfamilies containing clause operator */
/* cache space for mergeclause processing; NULL if not yet set */
EquivalenceClass *left_ec; /* EquivalenceClass containing lefthand */
EquivalenceClass *right_ec; /* EquivalenceClass containing righthand */
EquivalenceMember *left_em; /* EquivalenceMember for lefthand */
EquivalenceMember *right_em; /* EquivalenceMember for righthand */
List *scansel_cache; /* list of MergeScanSelCache structs */
/* transient workspace for use while considering a specific join path */
bool outer_is_left; /* T = outer var on left, F = on right */
/* valid if clause is hashjoinable, else InvalidOid: */
Oid hashjoinoperator; /* copy of clause operator */
/* cache space for hashclause processing; -1 if not yet set */
Selectivity left_bucketsize; /* avg bucketsize of left side */
Selectivity right_bucketsize; /* avg bucketsize of right side */
} RestrictInfo;
/*
* This macro embodies the correct way to test whether a RestrictInfo is
* "pushed down" to a given outer join, that is, should be treated as a filter
* clause rather than a join clause at that outer join. This is certainly so
* if is_pushed_down is true; but examining that is not sufficient anymore,
* because outer-join clauses will get pushed down to lower outer joins when
* we generate a path for the lower outer join that is parameterized by the
* LHS of the upper one. We can detect such a clause by noting that its
* required_relids exceed the scope of the join.
*/
#define RINFO_IS_PUSHED_DOWN(rinfo, joinrelids) \
((rinfo)->is_pushed_down || \
!bms_is_subset((rinfo)->required_relids, joinrelids))
/*
* Since mergejoinscansel() is a relatively expensive function, and would
* otherwise be invoked many times while planning a large join tree,
* we go out of our way to cache its results. Each mergejoinable
* RestrictInfo carries a list of the specific sort orderings that have
* been considered for use with it, and the resulting selectivities.
*/
typedef struct MergeScanSelCache
{
/* Ordering details (cache lookup key) */
Oid opfamily; /* btree opfamily defining the ordering */
Oid collation; /* collation for the ordering */
int strategy; /* sort direction (ASC or DESC) */
bool nulls_first; /* do NULLs come before normal values? */
/* Results */
Selectivity leftstartsel; /* first-join fraction for clause left side */
Selectivity leftendsel; /* last-join fraction for clause left side */
Selectivity rightstartsel; /* first-join fraction for clause right side */
Selectivity rightendsel; /* last-join fraction for clause right side */
} MergeScanSelCache;
/*
* Placeholder node for an expression to be evaluated below the top level
* of a plan tree. This is used during planning to represent the contained
* expression. At the end of the planning process it is replaced by either
* the contained expression or a Var referring to a lower-level evaluation of
* the contained expression. Typically the evaluation occurs below an outer
* join, and Var references above the outer join might thereby yield NULL
* instead of the expression value.
*
* Although the planner treats this as an expression node type, it is not
* recognized by the parser or executor, so we declare it here rather than
* in primnodes.h.
*/
typedef struct PlaceHolderVar
{
Expr xpr;
Expr *phexpr; /* the represented expression */
Relids phrels; /* base relids syntactically within expr src */
Index phid; /* ID for PHV (unique within planner run) */
Index phlevelsup; /* > 0 if PHV belongs to outer query */
} PlaceHolderVar;
/*
* "Special join" info.
*
* One-sided outer joins constrain the order of joining partially but not
* completely. We flatten such joins into the planner's top-level list of
* relations to join, but record information about each outer join in a
* SpecialJoinInfo struct. These structs are kept in the PlannerInfo node's
* join_info_list.
*
* Similarly, semijoins and antijoins created by flattening IN (subselect)
* and EXISTS(subselect) clauses create partial constraints on join order.
* These are likewise recorded in SpecialJoinInfo structs.
*
* We make SpecialJoinInfos for FULL JOINs even though there is no flexibility
* of planning for them, because this simplifies make_join_rel()'s API.
*
* min_lefthand and min_righthand are the sets of base relids that must be
* available on each side when performing the special join. lhs_strict is
* true if the special join's condition cannot succeed when the LHS variables
* are all NULL (this means that an outer join can commute with upper-level
* outer joins even if it appears in their RHS). We don't bother to set
* lhs_strict for FULL JOINs, however.
*
* It is not valid for either min_lefthand or min_righthand to be empty sets;
* if they were, this would break the logic that enforces join order.
*
* syn_lefthand and syn_righthand are the sets of base relids that are
* syntactically below this special join. (These are needed to help compute
* min_lefthand and min_righthand for higher joins.)
*
* delay_upper_joins is set TRUE if we detect a pushed-down clause that has
* to be evaluated after this join is formed (because it references the RHS).
* Any outer joins that have such a clause and this join in their RHS cannot
* commute with this join, because that would leave noplace to check the
* pushed-down clause. (We don't track this for FULL JOINs, either.)
*
* For a semijoin, we also extract the join operators and their RHS arguments
* and set semi_operators, semi_rhs_exprs, semi_can_btree, and semi_can_hash.
* This is done in support of possibly unique-ifying the RHS, so we don't
* bother unless at least one of semi_can_btree and semi_can_hash can be set
* true. (You might expect that this information would be computed during
* join planning; but it's helpful to have it available during planning of
* parameterized table scans, so we store it in the SpecialJoinInfo structs.)
*
* jointype is never JOIN_RIGHT; a RIGHT JOIN is handled by switching
* the inputs to make it a LEFT JOIN. So the allowed values of jointype
* in a join_info_list member are only LEFT, FULL, SEMI, or ANTI.
*
* For purposes of join selectivity estimation, we create transient
* SpecialJoinInfo structures for regular inner joins; so it is possible
* to have jointype == JOIN_INNER in such a structure, even though this is
* not allowed within join_info_list. We also create transient
* SpecialJoinInfos with jointype == JOIN_INNER for outer joins, since for
* cost estimation purposes it is sometimes useful to know the join size under
* plain innerjoin semantics. Note that lhs_strict, delay_upper_joins, and
* of course the semi_xxx fields are not set meaningfully within such structs.
*/
typedef struct SpecialJoinInfo
{
NodeTag type;
Relids min_lefthand; /* base relids in minimum LHS for join */
Relids min_righthand; /* base relids in minimum RHS for join */
Relids syn_lefthand; /* base relids syntactically within LHS */
Relids syn_righthand; /* base relids syntactically within RHS */
JoinType jointype; /* always INNER, LEFT, FULL, SEMI, or ANTI */
bool lhs_strict; /* joinclause is strict for some LHS rel */
bool delay_upper_joins; /* can't commute with upper RHS */
/* Remaining fields are set only for JOIN_SEMI jointype: */
bool semi_can_btree; /* true if semi_operators are all btree */
bool semi_can_hash; /* true if semi_operators are all hash */
List *semi_operators; /* OIDs of equality join operators */
List *semi_rhs_exprs; /* righthand-side expressions of these ops */
} SpecialJoinInfo;
/*
* Append-relation info.
*
* When we expand an inheritable table or a UNION-ALL subselect into an
* "append relation" (essentially, a list of child RTEs), we build an
* AppendRelInfo for each child RTE. The list of AppendRelInfos indicates
* which child RTEs must be included when expanding the parent, and each
* node carries information needed to translate Vars referencing the parent
* into Vars referencing that child.
*
* These structs are kept in the PlannerInfo node's append_rel_list.
* Note that we just throw all the structs into one list, and scan the
* whole list when desiring to expand any one parent. We could have used
* a more complex data structure (eg, one list per parent), but this would
* be harder to update during operations such as pulling up subqueries,
* and not really any easier to scan. Considering that typical queries
* will not have many different append parents, it doesn't seem worthwhile
* to complicate things.
*
* Note: after completion of the planner prep phase, any given RTE is an
* append parent having entries in append_rel_list if and only if its
* "inh" flag is set. We clear "inh" for plain tables that turn out not
* to have inheritance children, and (in an abuse of the original meaning
* of the flag) we set "inh" for subquery RTEs that turn out to be
* flattenable UNION ALL queries. This lets us avoid useless searches
* of append_rel_list.
*
* Note: the data structure assumes that append-rel members are single
* baserels. This is OK for inheritance, but it prevents us from pulling
* up a UNION ALL member subquery if it contains a join. While that could
* be fixed with a more complex data structure, at present there's not much
* point because no improvement in the plan could result.
*/
typedef struct AppendRelInfo
{
NodeTag type;
/*
* These fields uniquely identify this append relationship. There can be
* (in fact, always should be) multiple AppendRelInfos for the same
* parent_relid, but never more than one per child_relid, since a given
* RTE cannot be a child of more than one append parent.
*/
Index parent_relid; /* RT index of append parent rel */
Index child_relid; /* RT index of append child rel */
/*
* For an inheritance appendrel, the parent and child are both regular
* relations, and we store their rowtype OIDs here for use in translating
* whole-row Vars. For a UNION-ALL appendrel, the parent and child are
* both subqueries with no named rowtype, and we store InvalidOid here.
*/
Oid parent_reltype; /* OID of parent's composite type */
Oid child_reltype; /* OID of child's composite type */
/*
* The N'th element of this list is a Var or expression representing the
* child column corresponding to the N'th column of the parent. This is
* used to translate Vars referencing the parent rel into references to
* the child. A list element is NULL if it corresponds to a dropped
* column of the parent (this is only possible for inheritance cases, not
* UNION ALL). The list elements are always simple Vars for inheritance
* cases, but can be arbitrary expressions in UNION ALL cases.
*
* Notice we only store entries for user columns (attno > 0). Whole-row
* Vars are special-cased, and system columns (attno < 0) need no special
* translation since their attnos are the same for all tables.
*
* Caution: the Vars have varlevelsup = 0. Be careful to adjust as needed
* when copying into a subquery.
*/
List *translated_vars; /* Expressions in the child's Vars */
/*
* We store the parent table's OID here for inheritance, or InvalidOid for
* UNION ALL. This is only needed to help in generating error messages if
* an attempt is made to reference a dropped parent column.
*/
Oid parent_reloid; /* OID of parent relation */
} AppendRelInfo;
/*
* For each distinct placeholder expression generated during planning, we
* store a PlaceHolderInfo node in the PlannerInfo node's placeholder_list.
* This stores info that is needed centrally rather than in each copy of the
* PlaceHolderVar. The phid fields identify which PlaceHolderInfo goes with
* each PlaceHolderVar. Note that phid is unique throughout a planner run,
* not just within a query level --- this is so that we need not reassign ID's
* when pulling a subquery into its parent.
*
* The idea is to evaluate the expression at (only) the ph_eval_at join level,
* then allow it to bubble up like a Var until the ph_needed join level.
* ph_needed has the same definition as attr_needed for a regular Var.
*
* The PlaceHolderVar's expression might contain LATERAL references to vars
* coming from outside its syntactic scope. If so, those rels are *not*
* included in ph_eval_at, but they are recorded in ph_lateral.
*
* Notice that when ph_eval_at is a join rather than a single baserel, the
* PlaceHolderInfo may create constraints on join order: the ph_eval_at join
* has to be formed below any outer joins that should null the PlaceHolderVar.
*
* We create a PlaceHolderInfo only after determining that the PlaceHolderVar
* is actually referenced in the plan tree, so that unreferenced placeholders
* don't result in unnecessary constraints on join order.
*/
typedef struct PlaceHolderInfo
{
NodeTag type;
Index phid; /* ID for PH (unique within planner run) */
PlaceHolderVar *ph_var; /* copy of PlaceHolderVar tree */
Relids ph_eval_at; /* lowest level we can evaluate value at */
Relids ph_lateral; /* relids of contained lateral refs, if any */
Relids ph_needed; /* highest level the value is needed at */
int32 ph_width; /* estimated attribute width */
} PlaceHolderInfo;
/*
* This struct describes one potentially index-optimizable MIN/MAX aggregate
* function. MinMaxAggPath contains a list of these, and if we accept that
* path, the list is stored into root->minmax_aggs for use during setrefs.c.
*/
typedef struct MinMaxAggInfo
{
NodeTag type;
Oid aggfnoid; /* pg_proc Oid of the aggregate */
Oid aggsortop; /* Oid of its sort operator */
Expr *target; /* expression we are aggregating on */
PlannerInfo *subroot; /* modified "root" for planning the subquery */
Path *path; /* access path for subquery */
Cost pathcost; /* estimated cost to fetch first row */
Param *param; /* param for subplan's output */
} MinMaxAggInfo;
/*
* At runtime, PARAM_EXEC slots are used to pass values around from one plan
* node to another. They can be used to pass values down into subqueries (for
* outer references in subqueries), or up out of subqueries (for the results
* of a subplan), or from a NestLoop plan node into its inner relation (when
* the inner scan is parameterized with values from the outer relation).
* The planner is responsible for assigning nonconflicting PARAM_EXEC IDs to
* the PARAM_EXEC Params it generates.
*
* Outer references are managed via root->plan_params, which is a list of
* PlannerParamItems. While planning a subquery, each parent query level's
* plan_params contains the values required from it by the current subquery.
* During create_plan(), we use plan_params to track values that must be
* passed from outer to inner sides of NestLoop plan nodes.
*
* The item a PlannerParamItem represents can be one of three kinds:
*
* A Var: the slot represents a variable of this level that must be passed
* down because subqueries have outer references to it, or must be passed
* from a NestLoop node to its inner scan. The varlevelsup value in the Var
* will always be zero.
*
* A PlaceHolderVar: this works much like the Var case, except that the
* entry is a PlaceHolderVar node with a contained expression. The PHV
* will have phlevelsup = 0, and the contained expression is adjusted
* to match in level.
*
* An Aggref (with an expression tree representing its argument): the slot
* represents an aggregate expression that is an outer reference for some
* subquery. The Aggref itself has agglevelsup = 0, and its argument tree
* is adjusted to match in level.
*
* Note: we detect duplicate Var and PlaceHolderVar parameters and coalesce
* them into one slot, but we do not bother to do that for Aggrefs.
* The scope of duplicate-elimination only extends across the set of
* parameters passed from one query level into a single subquery, or for
* nestloop parameters across the set of nestloop parameters used in a single
* query level. So there is no possibility of a PARAM_EXEC slot being used
* for conflicting purposes.
*
* In addition, PARAM_EXEC slots are assigned for Params representing outputs
* from subplans (values that are setParam items for those subplans). These
* IDs need not be tracked via PlannerParamItems, since we do not need any
* duplicate-elimination nor later processing of the represented expressions.
* Instead, we just record the assignment of the slot number by incrementing
* root->glob->nParamExec.
*/
typedef struct PlannerParamItem
{
NodeTag type;
Node *item; /* the Var, PlaceHolderVar, or Aggref */
int paramId; /* its assigned PARAM_EXEC slot number */
} PlannerParamItem;
/*
* When making cost estimates for a SEMI or ANTI join, there are some
* correction factors that are needed in both nestloop and hash joins
* to account for the fact that the executor can stop scanning inner rows
* as soon as it finds a match to the current outer row. These numbers
* depend only on the selected outer and inner join relations, not on the
* particular paths used for them, so it's worthwhile to calculate them
* just once per relation pair not once per considered path. This struct
* is filled by compute_semi_anti_join_factors and must be passed along
* to the join cost estimation functions.
*
* outer_match_frac is the fraction of the outer tuples that are
* expected to have at least one match.
* match_count is the average number of matches expected for
* outer tuples that have at least one match.
*/
typedef struct SemiAntiJoinFactors
{
Selectivity outer_match_frac;
Selectivity match_count;
} SemiAntiJoinFactors;
/*
* Struct for extra information passed to subroutines of add_paths_to_joinrel
*
* restrictlist contains all of the RestrictInfo nodes for restriction
* clauses that apply to this join
* mergeclause_list is a list of RestrictInfo nodes for available
* mergejoin clauses in this join
* sjinfo is extra info about special joins for selectivity estimation
* semifactors is as shown above (only valid for SEMI or ANTI joins)
* param_source_rels are OK targets for parameterization of result paths
*/
typedef struct JoinPathExtraData
{
List *restrictlist;
List *mergeclause_list;
SpecialJoinInfo *sjinfo;
SemiAntiJoinFactors semifactors;
Relids param_source_rels;
} JoinPathExtraData;
/*
* For speed reasons, cost estimation for join paths is performed in two
* phases: the first phase tries to quickly derive a lower bound for the
* join cost, and then we check if that's sufficient to reject the path.
* If not, we come back for a more refined cost estimate. The first phase
* fills a JoinCostWorkspace struct with its preliminary cost estimates
* and possibly additional intermediate values. The second phase takes
* these values as inputs to avoid repeating work.
*
* (Ideally we'd declare this in cost.h, but it's also needed in pathnode.h,
* so seems best to put it here.)
*/
typedef struct JoinCostWorkspace
{
/* Preliminary cost estimates --- must not be larger than final ones! */
Cost startup_cost; /* cost expended before fetching any tuples */
Cost total_cost; /* total cost (assuming all tuples fetched) */
/* Fields below here should be treated as private to costsize.c */
Cost run_cost; /* non-startup cost components */
/* private for cost_nestloop code */
Cost inner_run_cost; /* also used by cost_mergejoin code */
Cost inner_rescan_run_cost;
/* private for cost_mergejoin code */
double outer_rows;
double inner_rows;
double outer_skip_rows;
double inner_skip_rows;
/* private for cost_hashjoin code */
int numbuckets;
int numbatches;
} JoinCostWorkspace;
#endif /* RELATION_H */
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