Take OUTER JOIN semantics into account when estimating the size of join
relations. It's not very bright, but at least it now knows that A LEFT JOIN B must produce at least as many rows as are in A ...
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@ -41,7 +41,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.67 2001/02/15 17:46:40 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.68 2001/02/16 00:03:07 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -837,11 +837,12 @@ void
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set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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RelOptInfo *outer_rel,
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RelOptInfo *outer_rel,
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RelOptInfo *inner_rel,
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RelOptInfo *inner_rel,
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JoinType jointype,
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List *restrictlist)
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List *restrictlist)
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{
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{
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double temp;
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double temp;
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/* cartesian product */
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/* Start with the Cartesian product */
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temp = outer_rel->rows * inner_rel->rows;
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temp = outer_rel->rows * inner_rel->rows;
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/*
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/*
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@ -854,6 +855,35 @@ set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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restrictlist,
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restrictlist,
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0);
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0);
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/*
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* If we are doing an outer join, take that into account: the output
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* must be at least as large as the non-nullable input. (Is there any
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* chance of being even smarter?)
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*/
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switch (jointype)
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{
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case JOIN_INNER:
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break;
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case JOIN_LEFT:
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if (temp < outer_rel->rows)
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temp = outer_rel->rows;
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break;
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case JOIN_RIGHT:
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if (temp < inner_rel->rows)
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temp = inner_rel->rows;
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break;
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case JOIN_FULL:
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if (temp < outer_rel->rows)
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temp = outer_rel->rows;
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if (temp < inner_rel->rows)
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temp = inner_rel->rows;
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break;
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default:
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elog(ERROR, "set_joinrel_size_estimates: unsupported join type %d",
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(int) jointype);
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break;
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}
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/*
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/*
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* Force estimate to be at least one row, to make explain output look
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* Force estimate to be at least one row, to make explain output look
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* better and to avoid possible divide-by-zero when interpolating
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* better and to avoid possible divide-by-zero when interpolating
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@ -861,6 +891,7 @@ set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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*/
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*/
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if (temp < 1.0)
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if (temp < 1.0)
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temp = 1.0;
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temp = 1.0;
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rel->rows = temp;
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rel->rows = temp;
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/*
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/*
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@ -8,7 +8,7 @@
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*
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*
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*
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*
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* IDENTIFICATION
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.50 2001/01/24 19:42:58 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.51 2001/02/16 00:03:07 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -394,7 +394,7 @@ make_join_rel(Query *root, RelOptInfo *rel1, RelOptInfo *rel2,
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* Find or build the join RelOptInfo, and compute the restrictlist
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* Find or build the join RelOptInfo, and compute the restrictlist
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* that goes with this particular joining.
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* that goes with this particular joining.
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*/
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*/
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joinrel = get_join_rel(root, rel1, rel2, &restrictlist);
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joinrel = get_join_rel(root, rel1, rel2, jointype, &restrictlist);
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/*
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/*
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* Consider paths using each rel as both outer and inner.
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* Consider paths using each rel as both outer and inner.
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@ -8,7 +8,7 @@
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*
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*
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*
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*
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* IDENTIFICATION
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.31 2001/01/24 19:43:00 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.32 2001/02/16 00:03:08 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -152,6 +152,7 @@ find_join_rel(Query *root, Relids relids)
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*
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*
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* 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
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* 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
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* joined
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* joined
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* 'jointype': type of join (inner/outer)
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* 'restrictlist_ptr': result variable. If not NULL, *restrictlist_ptr
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* 'restrictlist_ptr': result variable. If not NULL, *restrictlist_ptr
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* receives the list of RestrictInfo nodes that apply to this
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* receives the list of RestrictInfo nodes that apply to this
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* particular pair of joinable relations.
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* particular pair of joinable relations.
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@ -163,6 +164,7 @@ RelOptInfo *
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get_join_rel(Query *root,
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get_join_rel(Query *root,
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RelOptInfo *outer_rel,
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RelOptInfo *outer_rel,
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RelOptInfo *inner_rel,
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RelOptInfo *inner_rel,
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JoinType jointype,
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List **restrictlist_ptr)
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List **restrictlist_ptr)
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{
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{
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List *joinrelids;
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List *joinrelids;
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@ -252,7 +254,7 @@ get_join_rel(Query *root,
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* Set estimates of the joinrel's size.
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* Set estimates of the joinrel's size.
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*/
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*/
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set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel,
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set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel,
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restrictlist);
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jointype, restrictlist);
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/*
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/*
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* Add the joinrel to the query's joinrel list.
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* Add the joinrel to the query's joinrel list.
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* $Id: cost.h,v 1.37 2001/01/24 19:43:26 momjian Exp $
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* $Id: cost.h,v 1.38 2001/02/16 00:03:05 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -70,6 +70,7 @@ extern void set_baserel_size_estimates(Query *root, RelOptInfo *rel);
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extern void set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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extern void set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
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RelOptInfo *outer_rel,
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RelOptInfo *outer_rel,
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RelOptInfo *inner_rel,
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RelOptInfo *inner_rel,
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JoinType jointype,
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List *restrictlist);
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List *restrictlist);
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/*
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/*
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* $Id: pathnode.h,v 1.33 2001/01/24 19:43:26 momjian Exp $
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* $Id: pathnode.h,v 1.34 2001/02/16 00:03:06 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -66,8 +66,10 @@ extern HashPath *create_hashjoin_path(RelOptInfo *joinrel,
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*/
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*/
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extern RelOptInfo *get_base_rel(Query *root, int relid);
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extern RelOptInfo *get_base_rel(Query *root, int relid);
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extern RelOptInfo *make_base_rel(Query *root, int relid);
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extern RelOptInfo *make_base_rel(Query *root, int relid);
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extern RelOptInfo *get_join_rel(Query *root, RelOptInfo *outer_rel,
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extern RelOptInfo *get_join_rel(Query *root,
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RelOptInfo *inner_rel,
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RelOptInfo *outer_rel,
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List **restrictlist_ptr);
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RelOptInfo *inner_rel,
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JoinType jointype,
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List **restrictlist_ptr);
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#endif /* PATHNODE_H */
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#endif /* PATHNODE_H */
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