database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-22 12:22:45 +03:00
Code Activity

Simple constraint exclusion. For now, only child tables of inheritance

Browse Source 
scans are candidates for exclusion; this should be fixed eventually.
Simon Riggs, with some help from Tom Lane.
This commit is contained in:
Tom Lane
2005-07-23 21:05:48 +00:00
parent 9af9d674c6
commit d007a95055
14 changed files with 621 additions and 105 deletions
Download Patch File Download Diff File Expand all files Collapse all files

82
src/backend/optimizer/util/plancat.c
View File

@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.112 2005/06/13 23:14:48 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.113 2005/07/23 21:05:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -25,6 +25,7 @@
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/plancat.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "parser/parse_expr.h"
@@ -359,6 +360,85 @@ estimate_rel_size(Relation rel, int32 *attr_widths,
}
}
/*
* get_relation_constraints
*
* Retrieve the CHECK constraint expressions of the given relation.
*
* Returns a List (possibly empty) of constraint expressions. Each one
* has been canonicalized, and its Vars are changed to have the varno
* indicated by rel->relid. This allows the expressions to be easily
* compared to expressions taken from WHERE.
*
* Note: at present this is invoked at most once per relation per planner
* run, and in many cases it won't be invoked at all, so there seems no
* point in caching the data in RelOptInfo.
*/
List *
get_relation_constraints(Oid relationObjectId, RelOptInfo *rel)
{
List *result = NIL;
Index varno = rel->relid;
Relation relation;
TupleConstr *constr;
/*
* We assume the relation has already been safely locked.
*/
relation = heap_open(relationObjectId, NoLock);
constr = relation->rd_att->constr;
if (constr != NULL)
{
int num_check = constr->num_check;
int i;
for (i = 0; i < num_check; i++)
{
Node *cexpr;
cexpr = stringToNode(constr->check[i].ccbin);
/*
* Run each expression through const-simplification and
* canonicalization. This is not just an optimization, but is
* necessary, because we will be comparing it to
* similarly-processed qual clauses, and may fail to detect valid
* matches without this. This must match the processing done to
* qual clauses in preprocess_expression()! (We can skip the
* stuff involving subqueries, however, since we don't allow any
* in check constraints.)
*/
cexpr = eval_const_expressions(cexpr);
cexpr = (Node *) canonicalize_qual((Expr *) cexpr);
/*
* Also mark any coercion format fields as "don't care", so that
* we can match to both explicit and implicit coercions.
*/
set_coercionform_dontcare(cexpr);
/* Fix Vars to have the desired varno */
if (varno != 1)
ChangeVarNodes(cexpr, 1, varno, 0);
/*
* Finally, convert to implicit-AND format (that is, a List)
* and append the resulting item(s) to our output list.
*/
result = list_concat(result,
make_ands_implicit((Expr *) cexpr));
}
}
heap_close(relation, NoLock);
return result;
}
/*
* build_physical_tlist
*