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/*-------------------------------------------------------------------------
*
* spi_priv.h
* Server Programming Interface private declarations
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/executor/spi_priv.h
*
*-------------------------------------------------------------------------
*/
#ifndef SPI_PRIV_H
#define SPI_PRIV_H
#include "executor/spi.h"
#define _SPI_PLAN_MAGIC 569278163
typedef struct
{
/* current results */
uint64 processed; /* by Executor */
Oid lastoid;
SPITupleTable *tuptable; /* tuptable currently being built */
/* resources of this execution context */
slist_head tuptables; /* list of all live SPITupleTables */
MemoryContext procCxt; /* procedure context */
MemoryContext execCxt; /* executor context */
MemoryContext savedcxt; /* context of SPI_connect's caller */
SubTransactionId connectSubid; /* ID of connecting subtransaction */
/* subtransaction in which current Executor call was started */
SubTransactionId execSubid;
/* saved values of API global variables for previous nesting level */
uint64 outer_processed;
Oid outer_lastoid;
SPITupleTable *outer_tuptable;
int outer_result;
} _SPI_connection;
/*
* SPI plans have three states: saved, unsaved, or temporary.
*
* Ordinarily, the _SPI_plan struct itself as well as the argtypes array
* are in a dedicated memory context identified by plancxt (which can be
* really small). All the other subsidiary state is in plancache entries
* identified by plancache_list (note: the list cells themselves are in
* plancxt).
*
* In an unsaved plan, the plancxt as well as the plancache entries' contexts
* are children of the SPI procedure context, so they'll all disappear at
* function exit. plancache.c also knows that the plancache entries are
* "unsaved", so it doesn't link them into its global list; hence they do
* not respond to inval events. This is OK since we are presumably holding
* adequate locks to prevent other backends from messing with the tables.
*
* For a saved plan, the plancxt is made a child of CacheMemoryContext
* since it should persist until explicitly destroyed. Likewise, the
* plancache entries will be under CacheMemoryContext since we tell
* plancache.c to save them. We rely on plancache.c to keep the cache
* entries up-to-date as needed in the face of invalidation events.
*
* There are also "temporary" SPI plans, in which the _SPI_plan struct is
* not even palloc'd but just exists in some function's local variable.
* The plancache entries are unsaved and exist under the SPI executor context,
* while additional data such as argtypes and list cells is loose in the SPI
* executor context. Such plans can be identified by having plancxt == NULL.
*
* We can also have "one-shot" SPI plans (which are typically temporary,
* as described above). These are meant to be executed once and discarded,
* and various optimizations are made on the assumption of single use.
* Note in particular that the CachedPlanSources within such an SPI plan
* are not "complete" until execution.
*
* Note: if the original query string contained only whitespace and comments,
* the plancache_list will be NIL and so there is no place to store the
* query string. We don't care about that, but we do care about the
* argument type array, which is why it's seemingly-redundantly stored.
*/
typedef struct _SPI_plan
{
int magic; /* should equal _SPI_PLAN_MAGIC */
bool saved; /* saved or unsaved plan? */
bool oneshot; /* one-shot plan? */
List *plancache_list; /* one CachedPlanSource per parsetree */
MemoryContext plancxt; /* Context containing _SPI_plan and data */
int cursor_options; /* Cursor options used for planning */
int nargs; /* number of plan arguments */
Oid *argtypes; /* Argument types (NULL if nargs is 0) */
ParserSetupHook parserSetup; /* alternative parameter spec method */
void *parserSetupArg;
} _SPI_plan;
#endif /* SPI_PRIV_H */
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