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Reimplement CASE val WHEN compval1 THEN ... WHEN compval2 THEN ... END

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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.
This commit is contained in:
Tom Lane
2004-03-17 20:48:43 +00:00
parent 8c702ea7ac
commit 55f7c3300d
16 changed files with 248 additions and 55 deletions
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19
src/backend/nodes/copyfuncs.c
View File

@@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.278 2004/03/11 01:47:35 ishii Exp $
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.279 2004/03/17 20:48:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -968,6 +968,20 @@ _copyCaseWhen(CaseWhen *from)
return newnode;
}
/*
* _copyCaseTestExpr
*/
static CaseTestExpr *
_copyCaseTestExpr(CaseTestExpr *from)
{
CaseTestExpr *newnode = makeNode(CaseTestExpr);
COPY_SCALAR_FIELD(typeId);
COPY_SCALAR_FIELD(typeMod);
return newnode;
}
/*
* _copyArrayExpr
*/
@@ -2643,6 +2657,9 @@ copyObject(void *from)
case T_CaseWhen:
retval = _copyCaseWhen(from);
break;
case T_CaseTestExpr:
retval = _copyCaseTestExpr(from);
break;
case T_ArrayExpr:
retval = _copyArrayExpr(from);
break;

14
src/backend/nodes/equalfuncs.c
View File

@@ -18,7 +18,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.217 2004/03/14 23:41:26 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.218 2004/03/17 20:48:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -403,6 +403,15 @@ _equalCaseWhen(CaseWhen *a, CaseWhen *b)
return true;
}
static bool
_equalCaseTestExpr(CaseTestExpr *a, CaseTestExpr *b)
{
COMPARE_SCALAR_FIELD(typeId);
COMPARE_SCALAR_FIELD(typeMod);
return true;
}
static bool
_equalArrayExpr(ArrayExpr *a, ArrayExpr *b)
{
@@ -1724,6 +1733,9 @@ equal(void *a, void *b)
case T_CaseWhen:
retval = _equalCaseWhen(a, b);
break;
case T_CaseTestExpr:
retval = _equalCaseTestExpr(a, b);
break;
case T_ArrayExpr:
retval = _equalArrayExpr(a, b);
break;

14
src/backend/nodes/outfuncs.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.232 2004/01/31 05:09:40 neilc Exp $
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.233 2004/03/17 20:48:42 tgl Exp $
*
* NOTES
* Every node type that can appear in stored rules' parsetrees *must*
@@ -805,6 +805,15 @@ _outCaseWhen(StringInfo str, CaseWhen *node)
WRITE_NODE_FIELD(result);
}
static void
_outCaseTestExpr(StringInfo str, CaseTestExpr *node)
{
WRITE_NODE_TYPE("CASETESTEXPR");
WRITE_OID_FIELD(typeId);
WRITE_INT_FIELD(typeMod);
}
static void
_outArrayExpr(StringInfo str, ArrayExpr *node)
{
@@ -1701,6 +1710,9 @@ _outNode(StringInfo str, void *obj)
case T_CaseWhen:
_outCaseWhen(str, obj);
break;
case T_CaseTestExpr:
_outCaseTestExpr(str, obj);
break;
case T_ArrayExpr:
_outArrayExpr(str, obj);
break;

18
src/backend/nodes/readfuncs.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.165 2004/01/14 23:01:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.166 2004/03/17 20:48:42 tgl Exp $
*
* NOTES
* Path and Plan nodes do not have any readfuncs support, because we
@@ -648,6 +648,20 @@ _readCaseWhen(void)
READ_DONE();
}
/*
* _readCaseTestExpr
*/
static CaseTestExpr *
_readCaseTestExpr(void)
{
READ_LOCALS(CaseTestExpr);
READ_OID_FIELD(typeId);
READ_INT_FIELD(typeMod);
READ_DONE();
}
/*
* _readArrayExpr
*/
@@ -1010,6 +1024,8 @@ parseNodeString(void)
return_value = _readCaseExpr();
else if (MATCH("WHEN", 4))
return_value = _readCaseWhen();
else if (MATCH("CASETESTEXPR", 12))
return_value = _readCaseTestExpr();
else if (MATCH("ARRAY", 5))
return_value = _readArrayExpr();
else if (MATCH("COALESCE", 8))