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123 lines
5.2 KiB
C
123 lines
5.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* plancache.h
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* Plan cache definitions.
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*
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* See plancache.c for comments.
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*
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/plancache.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PLANCACHE_H
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#define PLANCACHE_H
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#include "access/tupdesc.h"
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#include "nodes/params.h"
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/*
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* CachedPlanSource represents the portion of a cached plan that persists
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* across invalidation/replan cycles. It stores a raw parse tree (required),
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* the original source text (also required, as of 8.4), and adjunct data.
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*
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* Normally, both the struct itself and the subsidiary data live in the
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* context denoted by the context field, while the linked-to CachedPlan, if
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* any, has its own context. Thus an invalidated CachedPlan can be dropped
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* when no longer needed, and conversely a CachedPlanSource can be dropped
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* without worrying whether any portals depend on particular instances of
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* its plan.
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*
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* But for entries created by FastCreateCachedPlan, the CachedPlanSource
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* and the initial version of the CachedPlan share the same memory context.
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* In this case, we treat the memory context as belonging to the CachedPlan.
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* The CachedPlanSource has an extra reference-counted link (orig_plan)
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* to the CachedPlan, and the memory context goes away when the CachedPlan's
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* reference count goes to zero. This arrangement saves overhead for plans
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* that aren't expected to live long enough to need replanning, while not
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* losing any flexibility if a replan turns out to be necessary.
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*
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* Note: the string referenced by commandTag is not subsidiary storage;
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* it is assumed to be a compile-time-constant string. As with portals,
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* commandTag shall be NULL if and only if the original query string (before
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* rewriting) was an empty string.
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*/
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typedef struct CachedPlanSource
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{
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Node *raw_parse_tree; /* output of raw_parser() */
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char *query_string; /* text of query (as of 8.4, never NULL) */
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const char *commandTag; /* command tag (a constant!), or NULL */
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Oid *param_types; /* array of parameter type OIDs, or NULL */
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int num_params; /* length of param_types array */
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ParserSetupHook parserSetup; /* alternative parameter spec method */
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void *parserSetupArg;
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int cursor_options; /* cursor options used for planning */
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bool fully_planned; /* do we cache planner or rewriter output? */
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bool fixed_result; /* disallow change in result tupdesc? */
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struct OverrideSearchPath *search_path; /* saved search_path */
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int generation; /* counter, starting at 1, for replans */
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TupleDesc resultDesc; /* result type; NULL = doesn't return tuples */
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struct CachedPlan *plan; /* link to plan, or NULL if not valid */
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MemoryContext context; /* context containing this CachedPlanSource */
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struct CachedPlan *orig_plan; /* link to plan owning my context */
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} CachedPlanSource;
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/*
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* CachedPlan represents the portion of a cached plan that is discarded when
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* invalidation occurs. The reference count includes both the link(s) from the
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* parent CachedPlanSource, and any active plan executions, so the plan can be
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* discarded exactly when refcount goes to zero. Both the struct itself and
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* the subsidiary data live in the context denoted by the context field.
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* This makes it easy to free a no-longer-needed cached plan.
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*/
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typedef struct CachedPlan
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{
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List *stmt_list; /* list of statement or Query nodes */
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bool fully_planned; /* do we cache planner or rewriter output? */
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bool dead; /* if true, do not use */
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TransactionId saved_xmin; /* if valid, replan when TransactionXmin
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* changes from this value */
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int refcount; /* count of live references to this struct */
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int generation; /* counter, starting at 1, for replans */
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MemoryContext context; /* context containing this CachedPlan */
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/* These fields are used only in the not-fully-planned case: */
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List *relationOids; /* OIDs of relations the stmts depend on */
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List *invalItems; /* other dependencies, as PlanInvalItems */
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} CachedPlan;
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extern void InitPlanCache(void);
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extern CachedPlanSource *CreateCachedPlan(Node *raw_parse_tree,
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const char *query_string,
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const char *commandTag,
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Oid *param_types,
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int num_params,
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int cursor_options,
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List *stmt_list,
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bool fully_planned,
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bool fixed_result);
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extern CachedPlanSource *FastCreateCachedPlan(Node *raw_parse_tree,
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char *query_string,
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const char *commandTag,
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Oid *param_types,
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int num_params,
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int cursor_options,
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List *stmt_list,
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bool fully_planned,
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bool fixed_result,
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MemoryContext context);
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extern void CachedPlanSetParserHook(CachedPlanSource *plansource,
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ParserSetupHook parserSetup,
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void *parserSetupArg);
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extern void DropCachedPlan(CachedPlanSource *plansource);
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extern CachedPlan *RevalidateCachedPlan(CachedPlanSource *plansource,
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bool useResOwner);
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extern void ReleaseCachedPlan(CachedPlan *plan, bool useResOwner);
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extern bool CachedPlanIsValid(CachedPlanSource *plansource);
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extern TupleDesc PlanCacheComputeResultDesc(List *stmt_list);
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extern void ResetPlanCache(void);
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#endif /* PLANCACHE_H */
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