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Commitc1943db

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Fix pg_get_ruledef() so that negative numeric constants are parenthesized.
This is needed because :: casting binds more tightly than minus, so forexample -1::integer is not the same as (-1)::integer, and there are caseswhere the difference is important. In particular this caused a failurein SELECT DISTINCT ... ORDER BY ... where expressions that should havematched were seen as different by the parser; but I suspect that therecould be other cases where failure to parenthesize leads to subtlersemantic differences in reloaded rules. Per report from Alexandr Popov.
1 parent700af33 commitc1943db

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‎src/backend/utils/adt/ruleutils.c‎

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.274 2008/05/12 00:00:51 alvherre Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.275 2008/06/06 17:59:29 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -4479,10 +4479,19 @@ get_const_expr(Const *constval, deparse_context *context, int showtype)
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*
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* In reality we only need to defend against infinity and NaN,
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* so we need not get too crazy about pattern matching here.
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*
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* There is a special-case gotcha: if the constant is signed,
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* we need to parenthesize it, else the parser might see a
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* leading plus/minus as binding less tightly than adjacent
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* operators --- particularly, the cast that we might attach
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* below.
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*/
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if (strspn(extval,"0123456789+-eE.")==strlen(extval))
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{
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appendStringInfoString(buf,extval);
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if (extval[0]=='+'||extval[0]=='-')
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appendStringInfo(buf,"(%s)",extval);
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else
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appendStringInfoString(buf,extval);
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if (strcspn(extval,"eE.")!=strlen(extval))
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isfloat= true;/* it looks like a float */
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}

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