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IN clauses appearing at top level of WHERE can now be handled as joins.

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There are two implementation techniques: the executor understands a new
JOIN_IN jointype, which emits at most one matching row per left-hand row,
or the result of the IN's sub-select can be fed through a DISTINCT filter
and then joined as an ordinary relation.
Along the way, some minor code cleanup in the optimizer; notably, break
out most of the jointree-rearrangement preprocessing in planner.c and
put it in a new file prep/prepjointree.c.
This commit is contained in:
Tom Lane
2003-01-20 18:55:07 +00:00
parent be2b660ecd
commit bdfbfde1b1
47 changed files with 2075 additions and 875 deletions
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60
src/backend/rewrite/rewriteManip.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.69 2003/01/17 02:01:16 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.70 2003/01/20 18:54:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -90,8 +90,8 @@ checkExprHasSubLink_walker(Node *node, void *context)
*
* Find all Var nodes in the given tree with varlevelsup == sublevels_up,
* and increment their varno fields (rangetable indexes) by 'offset'.
* The varnoold fields are adjusted similarly. Also, RangeTblRef and
* JoinExpr nodes in join trees and setOp trees are adjusted.
* The varnoold fields are adjusted similarly. Also, adjust other nodes
* that contain rangetable indexes, such as RangeTblRef and JoinExpr.
*
* NOTE: although this has the form of a walker, we cheat and modify the
* nodes in-place. The given expression tree should have been copied
@ -137,6 +137,25 @@ OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
j->rtindex += context->offset;
/* fall through to examine children */
}
if (IsA(node, InClauseInfo))
{
InClauseInfo *ininfo = (InClauseInfo *) node;
if (context->sublevels_up == 0)
{
List *rt;
foreach(rt, ininfo->lefthand)
{
lfirsti(rt) += context->offset;
}
foreach(rt, ininfo->righthand)
{
lfirsti(rt) += context->offset;
}
}
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
@ -196,8 +215,8 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
*
* Find all Var nodes in the given tree belonging to a specific relation
* (identified by sublevels_up and rt_index), and change their varno fields
* to 'new_index'. The varnoold fields are changed too. Also, RangeTblRef
* and JoinExpr nodes in join trees and setOp trees are adjusted.
* to 'new_index'. The varnoold fields are changed too. Also, adjust other
* nodes that contain rangetable indexes, such as RangeTblRef and JoinExpr.
*
* NOTE: although this has the form of a walker, we cheat and modify the
* nodes in-place. The given expression tree should have been copied
@ -247,6 +266,27 @@ ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
j->rtindex = context->new_index;
/* fall through to examine children */
}
if (IsA(node, InClauseInfo))
{
InClauseInfo *ininfo = (InClauseInfo *) node;
if (context->sublevels_up == 0)
{
List *rt;
foreach(rt, ininfo->lefthand)
{
if (lfirsti(rt) == context->rt_index)
lfirsti(rt) = context->new_index;
}
foreach(rt, ininfo->righthand)
{
if (lfirsti(rt) == context->rt_index)
lfirsti(rt) = context->new_index;
}
}
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
@ -423,6 +463,16 @@ rangeTableEntry_used_walker(Node *node,
return true;
/* fall through to examine children */
}
if (IsA(node, InClauseInfo))
{
InClauseInfo *ininfo = (InClauseInfo *) node;
if (context->sublevels_up == 0 &&
(intMember(context->rt_index, ininfo->lefthand) ||
intMember(context->rt_index, ininfo->righthand)))
return true;
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */