diff options
Diffstat (limited to 'src/include/utils/plancache.h')
| -rw-r--r-- | src/include/utils/plancache.h | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h index a447eaccc58..8185427fc4b 100644 --- a/src/include/utils/plancache.h +++ b/src/include/utils/plancache.h @@ -60,6 +60,14 @@ * context that holds the rewritten query tree and associated data. This * allows the query tree to be discarded easily when it is invalidated. * + * Some callers wish to use the CachedPlan API even with one-shot queries + * that have no reason to be saved at all. We therefore support a "oneshot" + * variant that does no data copying or invalidation checking. In this case + * there are no separate memory contexts: the CachedPlanSource struct and + * all subsidiary data live in the caller's CurrentMemoryContext, and there + * is no way to free memory short of clearing that entire context. A oneshot + * plan is always treated as unsaved. + * * Note: the string referenced by commandTag is not subsidiary storage; * it is assumed to be a compile-time-constant string. As with portals, * commandTag shall be NULL if and only if the original query string (before @@ -69,7 +77,7 @@ typedef struct CachedPlanSource { int magic; /* should equal CACHEDPLANSOURCE_MAGIC */ Node *raw_parse_tree; /* output of raw_parser() */ - char *query_string; /* source text of query */ + const char *query_string; /* source text of query */ const char *commandTag; /* command tag (a constant!), or NULL */ Oid *param_types; /* array of parameter type OIDs, or NULL */ int num_params; /* length of param_types array */ @@ -88,6 +96,7 @@ typedef struct CachedPlanSource /* If we have a generic plan, this is a reference-counted link to it: */ struct CachedPlan *gplan; /* generic plan, or NULL if not valid */ /* Some state flags: */ + bool is_oneshot; /* is it a "oneshot" plan? */ bool is_complete; /* has CompleteCachedPlan been done? */ bool is_saved; /* has CachedPlanSource been "saved"? */ bool is_valid; /* is the query_list currently valid? */ @@ -106,13 +115,16 @@ typedef struct CachedPlanSource * (if any), and any active plan executions, so the plan can be discarded * exactly when refcount goes to zero. Both the struct itself and the * subsidiary data live in the context denoted by the context field. - * This makes it easy to free a no-longer-needed cached plan. + * This makes it easy to free a no-longer-needed cached plan. (However, + * if is_oneshot is true, the context does not belong solely to the CachedPlan + * so no freeing is possible.) */ typedef struct CachedPlan { int magic; /* should equal CACHEDPLAN_MAGIC */ List *stmt_list; /* list of statement nodes (PlannedStmts and * bare utility statements) */ + bool is_oneshot; /* is it a "oneshot" plan? */ bool is_saved; /* is CachedPlan in a long-lived context? */ bool is_valid; /* is the stmt_list currently valid? */ TransactionId saved_xmin; /* if valid, replan when TransactionXmin @@ -129,6 +141,9 @@ extern void ResetPlanCache(void); extern CachedPlanSource *CreateCachedPlan(Node *raw_parse_tree, const char *query_string, const char *commandTag); +extern CachedPlanSource *CreateOneShotCachedPlan(Node *raw_parse_tree, + const char *query_string, + const char *commandTag); extern void CompleteCachedPlan(CachedPlanSource *plansource, List *querytree_list, MemoryContext querytree_context, |