diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/pl/plpgsql/src/pl_exec.c | 20 | ||||
| -rw-r--r-- | src/pl/plpgsql/src/plpgsql.h | 1 |
2 files changed, 16 insertions, 5 deletions
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c index fd799b724da..4a9ed83030a 100644 --- a/src/pl/plpgsql/src/pl_exec.c +++ b/src/pl/plpgsql/src/pl_exec.c @@ -6079,6 +6079,7 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate, LocalTransactionId curlxid = MyProc->lxid; CachedPlan *cplan; void *save_setup_arg; + bool need_snapshot; MemoryContext oldcontext; /* @@ -6150,12 +6151,19 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate, /* * We have to do some of the things SPI_execute_plan would do, in - * particular advance the snapshot if we are in a non-read-only function. - * Without this, stable functions within the expression would fail to see - * updates made so far by our own function. + * particular push a new snapshot so that stable functions within the + * expression can see updates made so far by our own function. However, + * we can skip doing that (and just invoke the expression with the same + * snapshot passed to our function) in some cases, which is useful because + * it's quite expensive relative to the cost of a simple expression. We + * can skip it if the expression contains no stable or volatile functions; + * immutable functions shouldn't need to see our updates. Also, if this + * is a read-only function, we haven't made any updates so again it's okay + * to skip. */ oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate)); - if (!estate->readonly_func) + need_snapshot = (expr->expr_simple_mutable && !estate->readonly_func); + if (need_snapshot) { CommandCounterIncrement(); PushActiveSnapshot(GetTransactionSnapshot()); @@ -6180,7 +6188,7 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate, estate->paramLI->parserSetupArg = save_setup_arg; - if (!estate->readonly_func) + if (need_snapshot) PopActiveSnapshot(); MemoryContextSwitchTo(oldcontext); @@ -8051,6 +8059,8 @@ exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan) /* Also stash away the expression result type */ expr->expr_simple_type = exprType((Node *) tle_expr); expr->expr_simple_typmod = exprTypmod((Node *) tle_expr); + /* We also want to remember if it is immutable or not */ + expr->expr_simple_mutable = contain_mutable_functions((Node *) tle_expr); } /* diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h index f66b2baa70a..6b40fcd1963 100644 --- a/src/pl/plpgsql/src/plpgsql.h +++ b/src/pl/plpgsql/src/plpgsql.h @@ -234,6 +234,7 @@ typedef struct PLpgSQL_expr int expr_simple_generation; /* plancache generation we checked */ Oid expr_simple_type; /* result type Oid, if simple */ int32 expr_simple_typmod; /* result typmod, if simple */ + bool expr_simple_mutable; /* true if simple expr is mutable */ /* * if expr is simple AND prepared in current transaction, |