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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/utils/adt/ruleutils.c
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@ -6884,6 +6884,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
case T_RowExpr:
case T_CoalesceExpr:
case T_MinMaxExpr:
case T_SQLValueFunction:
case T_XmlExpr:
case T_NullIfExpr:
case T_Aggref:
@ -7871,6 +7872,67 @@ get_rule_expr(Node *node, deparse_context *context,
}
break;
case T_SQLValueFunction:
{
SQLValueFunction *svf = (SQLValueFunction *) node;
/*
* Note: this code knows that typmod for time, timestamp, and
* timestamptz just prints as integer.
*/
switch (svf->op)
{
case SVFOP_CURRENT_DATE:
appendStringInfoString(buf, "CURRENT_DATE");
break;
case SVFOP_CURRENT_TIME:
appendStringInfoString(buf, "CURRENT_TIME");
break;
case SVFOP_CURRENT_TIME_N:
appendStringInfo(buf, "CURRENT_TIME(%d)", svf->typmod);
break;
case SVFOP_CURRENT_TIMESTAMP:
appendStringInfoString(buf, "CURRENT_TIMESTAMP");
break;
case SVFOP_CURRENT_TIMESTAMP_N:
appendStringInfo(buf, "CURRENT_TIMESTAMP(%d)",
svf->typmod);
break;
case SVFOP_LOCALTIME:
appendStringInfoString(buf, "LOCALTIME");
break;
case SVFOP_LOCALTIME_N:
appendStringInfo(buf, "LOCALTIME(%d)", svf->typmod);
break;
case SVFOP_LOCALTIMESTAMP:
appendStringInfoString(buf, "LOCALTIMESTAMP");
break;
case SVFOP_LOCALTIMESTAMP_N:
appendStringInfo(buf, "LOCALTIMESTAMP(%d)",
svf->typmod);
break;
case SVFOP_CURRENT_ROLE:
appendStringInfoString(buf, "CURRENT_ROLE");
break;
case SVFOP_CURRENT_USER:
appendStringInfoString(buf, "CURRENT_USER");
break;
case SVFOP_USER:
appendStringInfoString(buf, "USER");
break;
case SVFOP_SESSION_USER:
appendStringInfoString(buf, "SESSION_USER");
break;
case SVFOP_CURRENT_CATALOG:
appendStringInfoString(buf, "CURRENT_CATALOG");
break;
case SVFOP_CURRENT_SCHEMA:
appendStringInfoString(buf, "CURRENT_SCHEMA");
break;
}
}
break;
case T_XmlExpr:
{
XmlExpr *xexpr = (XmlExpr *) node;