database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

Improve parsetree representation of special functions such as CURRENT_DATE.

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

16
src/backend/optimizer/util/clauses.c
View File

@ -962,6 +962,12 @@ contain_mutable_functions_walker(Node *node, void *context)
context))
return true;
if (IsA(node, SQLValueFunction))
{
/* all variants of SQLValueFunction are stable */
return true;
}
/*
* It should be safe to treat MinMaxExpr as immutable, because it will
* depend on a non-cross-type btree comparison function, and those should
@ -1031,7 +1037,8 @@ contain_volatile_functions_walker(Node *node, void *context)
/*
* See notes in contain_mutable_functions_walker about why we treat
* MinMaxExpr, XmlExpr, and CoerceToDomain as immutable.
* MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
* SQLValueFunction is stable. Hence, none of them are of interest here.
*/
/* Recurse to check arguments */
@ -1076,7 +1083,8 @@ contain_volatile_functions_not_nextval_walker(Node *node, void *context)
/*
* See notes in contain_mutable_functions_walker about why we treat
* MinMaxExpr, XmlExpr, and CoerceToDomain as immutable.
* MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
* SQLValueFunction is stable. Hence, none of them are of interest here.
*/
/* Recurse to check arguments */
@ -1143,7 +1151,8 @@ has_parallel_hazard_walker(Node *node, has_parallel_hazard_arg *context)
* (Note: in principle that's wrong because a domain constraint could
* contain a parallel-unsafe function; but useful constraints probably
* never would have such, and assuming they do would cripple use of
* parallel query in the presence of domain types.)
* parallel query in the presence of domain types.) SQLValueFunction
* should be safe in all cases.
*/
if (IsA(node, CoerceToDomain))
{
@ -1458,6 +1467,7 @@ contain_leaked_vars_walker(Node *node, void *context)
case T_CaseTestExpr:
case T_RowExpr:
case T_MinMaxExpr:
case T_SQLValueFunction:
case T_NullTest:
case T_BooleanTest:
case T_List: