From 55f7c3300d164d370d28b127210223d078da524d Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 17 Mar 2004 20:48:43 +0000 Subject: Reimplement CASE val WHEN compval1 THEN ... WHEN compval2 THEN ... END so that the 'val' is computed only once, per recent discussion. The speedup is not much when 'val' is just a simple variable, but could be significant for larger expressions. More importantly this avoids issues with multiple evaluations of a volatile 'val', and it allows the CASE expression to be reverse-listed in its original form by ruleutils.c. --- src/backend/utils/adt/ruleutils.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) (limited to 'src/backend/utils/adt/ruleutils.c') diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 7e1513796db..3960152f387 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -3,7 +3,7 @@ * back to source text * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.162 2004/01/31 05:09:40 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.163 2004/03/17 20:48:42 tgl Exp $ * * This software is copyrighted by Jan Wieck - Hamburg. * @@ -2564,7 +2564,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags) case T_ArrayExpr: /* other separators */ case T_CoalesceExpr: /* own parentheses */ case T_NullIfExpr: /* other separators */ - case T_Aggref: /* own parentheses */ + case T_Aggref: /* own parentheses */ case T_CaseExpr: /* other separators */ return true; default: @@ -2610,7 +2610,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags) case T_ArrayExpr: /* other separators */ case T_CoalesceExpr: /* own parentheses */ case T_NullIfExpr: /* other separators */ - case T_Aggref: /* own parentheses */ + case T_Aggref: /* own parentheses */ case T_CaseExpr: /* other separators */ return true; default: @@ -3026,6 +3026,11 @@ get_rule_expr(Node *node, deparse_context *context, appendContextKeyword(context, "CASE", 0, PRETTYINDENT_VAR, 0); + if (caseexpr->arg) + { + appendStringInfoChar(buf, ' '); + get_rule_expr((Node *) caseexpr->arg, context, true); + } foreach(temp, caseexpr->args) { CaseWhen *when = (CaseWhen *) lfirst(temp); @@ -3034,7 +3039,17 @@ get_rule_expr(Node *node, deparse_context *context, appendStringInfoChar(buf, ' '); appendContextKeyword(context, "WHEN ", 0, 0, 0); - get_rule_expr((Node *) when->expr, context, false); + if (caseexpr->arg) + { + /* Show only the RHS of "CaseTestExpr = RHS" */ + Node *rhs; + + Assert(IsA(when->expr, OpExpr)); + rhs = (Node *) lsecond(((OpExpr *) when->expr)->args); + get_rule_expr(rhs, context, false); + } + else + get_rule_expr((Node *) when->expr, context, false); appendStringInfo(buf, " THEN "); get_rule_expr((Node *) when->result, context, true); } -- cgit v1.2.3