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Improve parsetree representation of special functions such as CURRENT_DATE.

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We implement a dozen or so parameterless functions that the SQL standard
defines special syntax for.  Up to now, that was done by converting them
into more or less ad-hoc constructs such as "'now'::text::date".  That's
messy for multiple reasons: it exposes what should be implementation
details to users, and performance is worse than it needs to be in several
cases.  To improve matters, invent a new expression node type
SQLValueFunction that can represent any of these parameterless functions.

Bump catversion because this changes stored parsetrees for rules.

Discussion: <30058.1463091294@sss.pgh.pa.us>
This commit is contained in:
Tom Lane
2016-08-16 20:33:01 -04:00
parent 4bc4cfe3bd
commit 0bb51aa967
24 changed files with 626 additions and 168 deletions
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62
src/backend/parser/parse_expr.c
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@ -34,7 +34,9 @@
#include "parser/parse_type.h"
#include "parser/parse_agg.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/lsyscache.h"
#include "utils/timestamp.h"
#include "utils/xml.h"
@ -107,6 +109,8 @@ static Node *transformArrayExpr(ParseState *pstate, A_ArrayExpr *a,
static Node *transformRowExpr(ParseState *pstate, RowExpr *r);
static Node *transformCoalesceExpr(ParseState *pstate, CoalesceExpr *c);
static Node *transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m);
static Node *transformSQLValueFunction(ParseState *pstate,
SQLValueFunction *svf);
static Node *transformXmlExpr(ParseState *pstate, XmlExpr *x);
static Node *transformXmlSerialize(ParseState *pstate, XmlSerialize *xs);
static Node *transformBooleanTest(ParseState *pstate, BooleanTest *b);
@ -306,6 +310,11 @@ transformExprRecurse(ParseState *pstate, Node *expr)
result = transformMinMaxExpr(pstate, (MinMaxExpr *) expr);
break;
case T_SQLValueFunction:
result = transformSQLValueFunction(pstate,
(SQLValueFunction *) expr);
break;
case T_XmlExpr:
result = transformXmlExpr(pstate, (XmlExpr *) expr);
break;
@ -2178,6 +2187,59 @@ transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m)
return (Node *) newm;
}
static Node *
transformSQLValueFunction(ParseState *pstate, SQLValueFunction *svf)
{
/*
* All we need to do is insert the correct result type and (where needed)
* validate the typmod, so we just modify the node in-place.
*/
switch (svf->op)
{
case SVFOP_CURRENT_DATE:
svf->type = DATEOID;
break;
case SVFOP_CURRENT_TIME:
svf->type = TIMETZOID;
break;
case SVFOP_CURRENT_TIME_N:
svf->type = TIMETZOID;
svf->typmod = anytime_typmod_check(true, svf->typmod);
break;
case SVFOP_CURRENT_TIMESTAMP:
svf->type = TIMESTAMPTZOID;
break;
case SVFOP_CURRENT_TIMESTAMP_N:
svf->type = TIMESTAMPTZOID;
svf->typmod = anytimestamp_typmod_check(true, svf->typmod);
break;
case SVFOP_LOCALTIME:
svf->type = TIMEOID;
break;
case SVFOP_LOCALTIME_N:
svf->type = TIMEOID;
svf->typmod = anytime_typmod_check(false, svf->typmod);
break;
case SVFOP_LOCALTIMESTAMP:
svf->type = TIMESTAMPOID;
break;
case SVFOP_LOCALTIMESTAMP_N:
svf->type = TIMESTAMPOID;
svf->typmod = anytimestamp_typmod_check(false, svf->typmod);
break;
case SVFOP_CURRENT_ROLE:
case SVFOP_CURRENT_USER:
case SVFOP_USER:
case SVFOP_SESSION_USER:
case SVFOP_CURRENT_CATALOG:
case SVFOP_CURRENT_SCHEMA:
svf->type = NAMEOID;
break;
}
return (Node *) svf;
}
static Node *
transformXmlExpr(ParseState *pstate, XmlExpr *x)
{