From f2eac8057d61ecd201d4e3aaebf35751ef7f63a9 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 29 Jan 2025 20:56:18 -0500 Subject: [PATCH v1 6/8] Remove plpgsql's abuse of CaseTestExpr. We can use a PARAM_EXTERN Param almost as easily as a CaseTestExpr, since the cast expression this is used in has no need to access any other Params. At this point, the executor's support for CaseTestExpr is dead code, because such nodes will never get past the planner. I'll leave removing that for a separate patch, though. --- src/pl/plpgsql/src/pl_exec.c | 47 +++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 12 deletions(-) diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c index 35cda55cf9..e1f7067b1a 100644 --- a/src/pl/plpgsql/src/pl_exec.c +++ b/src/pl/plpgsql/src/pl_exec.c @@ -170,6 +170,7 @@ typedef struct /* cast_hash table entry */ plpgsql_CastExprHashEntry *cast_centry; /* link to matching expr entry */ /* ExprState is valid only when cast_lxid matches current LXID */ ExprState *cast_exprstate; /* expression's eval tree */ + ParamListInfo cast_params; /* input Param value for cast expr */ bool cast_in_use; /* true while we're executing eval tree */ LocalTransactionId cast_lxid; } plpgsql_CastHashEntry; @@ -7754,18 +7755,29 @@ do_cast_value(PLpgSQL_execstate *estate, if (cast_entry) { ExprContext *econtext = estate->eval_econtext; + ParamListInfo paramLI; MemoryContext oldcontext; oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate)); - econtext->caseValue_datum = value; - econtext->caseValue_isNull = *isnull; - cast_entry->cast_in_use = true; + /* Set up the value for the cast expression's Param */ + paramLI = cast_entry->cast_params; + paramLI->params[0].value = value; + paramLI->params[0].isnull = *isnull; + + /* + * Someday we might need to save-n-restore ecxt_param_list_info here, + * but that day is not yet: it's always NULL except during expr eval. + */ + econtext->ecxt_param_list_info = paramLI; + value = ExecEvalExpr(cast_entry->cast_exprstate, econtext, isnull); + econtext->ecxt_param_list_info = NULL; + cast_entry->cast_in_use = false; MemoryContextSwitchTo(oldcontext); @@ -7780,7 +7792,7 @@ do_cast_value(PLpgSQL_execstate *estate, * Returns a plpgsql_CastHashEntry if an expression has to be evaluated, * or NULL if the cast is a mere no-op relabeling. If there's work to be * done, the cast_exprstate field contains an expression evaluation tree - * based on a CaseTestExpr input, and the cast_in_use field should be set + * based on a PARAM_EXTERN parameter, and the cast_in_use field should be set * true while executing it. * ---------- */ @@ -7816,6 +7828,7 @@ get_cast_hashentry(PLpgSQL_execstate *estate, cast_entry->cast_centry = expr_entry; cast_entry->cast_exprstate = NULL; + cast_entry->cast_params = NULL; cast_entry->cast_in_use = false; cast_entry->cast_lxid = InvalidLocalTransactionId; } @@ -7834,7 +7847,7 @@ get_cast_hashentry(PLpgSQL_execstate *estate, */ Node *cast_expr; CachedExpression *cast_cexpr; - CaseTestExpr *placeholder; + Param *placeholder; /* * Drop old cached expression if there is one. @@ -7853,13 +7866,16 @@ get_cast_hashentry(PLpgSQL_execstate *estate, oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate)); /* - * We use a CaseTestExpr as the base of the coercion tree, since it's - * very cheap to insert the source value for that. + * We use a PARAM_EXTERN Param as the base of the coercion tree. The + * cast expression will not contain any other such Params. */ - placeholder = makeNode(CaseTestExpr); - placeholder->typeId = srctype; - placeholder->typeMod = srctypmod; - placeholder->collation = get_typcollation(srctype); + placeholder = makeNode(Param); + placeholder->paramkind = PARAM_EXTERN; + placeholder->paramid = 1; + placeholder->paramtype = srctype; + placeholder->paramtypmod = srctypmod; + placeholder->paramcollid = get_typcollation(srctype); + placeholder->location = -1; /* * Apply coercion. We use the special coercion context @@ -7929,6 +7945,7 @@ get_cast_hashentry(PLpgSQL_execstate *estate, /* Be sure to reset the exprstate hashtable entry, too. */ cast_entry->cast_exprstate = NULL; + cast_entry->cast_params = NULL; cast_entry->cast_in_use = false; cast_entry->cast_lxid = InvalidLocalTransactionId; @@ -7954,8 +7971,14 @@ get_cast_hashentry(PLpgSQL_execstate *estate, curlxid = MyProc->vxid.lxid; if (cast_entry->cast_lxid != curlxid || cast_entry->cast_in_use) { + ParamListInfo paramLI; + oldcontext = MemoryContextSwitchTo(estate->simple_eval_estate->es_query_cxt); - cast_entry->cast_exprstate = ExecInitExpr(expr_entry->cast_expr, NULL); + cast_entry->cast_params = paramLI = makeParamList(1); + paramLI->params[0].pflags = 0; + paramLI->params[0].ptype = srctype; + cast_entry->cast_exprstate = ExecInitExprWithParams(expr_entry->cast_expr, + paramLI); cast_entry->cast_in_use = false; cast_entry->cast_lxid = curlxid; MemoryContextSwitchTo(oldcontext); -- 2.43.5