enable_constraint_exclusion => constraint_exclusion
Also improve wording.
This commit is contained in:
Bruce Momjian
parent
8ad3965a11
commit
a7f49252d2
4
doc/TODO
4
doc/TODO
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@ -385,7 +385,7 @@ SQL Commands
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* Add GUC to issue notice about queries that use unjoined tables
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* Allow EXPLAIN to identify tables that were skipped because of
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enable_constraint_exclusion
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constraint_exclusion
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* Allow EXPLAIN output to be more easily processed by scripts
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@ -769,7 +769,7 @@ Indexes
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* Allow the creation of indexes with mixed ascending/descending specifiers
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* -Fix incorrect rtree results due to wrong assumptions about "over"
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operator semantics
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* Allow enable_constraint_exclusion to work for UNIONs like it does for
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* Allow constraint_exclusion to work for UNIONs like it does for
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inheritance, and allow it to work for UPDATE and DELETE queries
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@ -355,7 +355,7 @@ first.
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</p>
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</li><li>Add GUC to issue notice about queries that use unjoined tables
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</li><li>Allow EXPLAIN to identify tables that were skipped because of
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enable_constraint_exclusion
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constraint_exclusion
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</li><li>Allow EXPLAIN output to be more easily processed by scripts
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</li><li>CREATE
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<ul>
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@ -694,7 +694,7 @@ first.
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</li><li>Allow the creation of indexes with mixed ascending/descending specifiers
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</li><li>-<em>Fix incorrect rtree results due to wrong assumptions about "over"</em>
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operator semantics
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</li><li>Allow enable_constraint_exclusion to work for UNIONs like it does for
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</li><li>Allow constraint_exclusion to work for UNIONs like it does for
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inheritance, and allow it to work for UPDATE and DELETE queries
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</li><li>GIST
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<ul>
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@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.346 2005/08/21 03:39:26 tgl Exp $
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$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.347 2005/08/22 17:34:56 momjian Exp $
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-->
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<chapter Id="runtime">
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@ -2352,24 +2352,24 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
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</listitem>
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</varlistentry>
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<varlistentry id="guc-enable-constraint-exclusion" xreflabel="enable_constraint_exclusion">
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<term><varname>enable_constraint_exclusion</varname> (<type>boolean</type>)</term>
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<varlistentry id="guc-constraint-exclusion" xreflabel="constraint_exclusion">
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<term><varname>constraint_exclusion</varname> (<type>boolean</type>)</term>
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<indexterm>
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<primary>constraint exclusion</primary>
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</indexterm>
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<indexterm>
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<primary><varname>enable_constraint_exclusion</> configuration parameter</primary>
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<primary><varname>constraint_exclusion</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Enables or disables the query planner's use of table constraints.
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The default is <literal>off</>.
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Enables or disables the query planner's use of table constraints to
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limit table access. The default is <literal>off</>.
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</para>
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<para>
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When this parameter is <literal>on</>, the planner compares query
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conditions to table CHECK constraints, and omits scanning tables
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for which the conditions contradict the constraints. (Presently
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conditions with table CHECK constraints, and omits scanning tables
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where the conditions contradict the constraints. (Presently
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this is done only for child tables of inheritance scans.) For
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example:
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@ -2387,15 +2387,15 @@ SELECT * FROM parent WHERE key = 2400;
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</para>
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<para>
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Currently, <varname>enable_constraint_exclusion</> defaults to
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<literal>off</>, because it creates a risk of wrong answers when
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query plans are cached: if a table constraint is changed or dropped,
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the previously generated plan may now be wrong, and there is no
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Currently, <varname>constraint_exclusion</> defaults to
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<literal>off</>, because it risks incorrect results if
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query plans are cached --- if a table constraint is changed or dropped,
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the previously generated plan might now be wrong, and there is no
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built-in mechanism to force re-planning. (This deficiency will
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probably be addressed in a future
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<productname>PostgreSQL</productname> release.) Another reason
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for keeping it off is that the constraint checks are relatively
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expensive to make, and in many circumstances will yield no savings.
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expensive, and in many circumstances will yield no savings.
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It is recommended to turn this on only if you are actually using
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partitioned tables designed to take advantage of the feature.
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</para>
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.135 2005/07/23 21:05:46 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.136 2005/08/22 17:34:58 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -36,7 +36,7 @@
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/* These parameters are set by GUC */
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bool enable_constraint_exclusion = false;
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bool constraint_exclusion = false;
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bool enable_geqo = false; /* just in case GUC doesn't set it */
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int geqo_threshold;
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@ -318,7 +318,7 @@ set_inherited_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
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* exclusion, just ignore it. (We have to have converted the
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* baserestrictinfo Vars before we can make the test.)
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*/
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if (enable_constraint_exclusion)
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if (constraint_exclusion)
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{
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List *constraint_pred;
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@ -10,7 +10,7 @@
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* Written by Peter Eisentraut <peter_e@gmx.net>.
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.285 2005/08/21 03:39:34 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.286 2005/08/22 17:34:59 momjian Exp $
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*
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*--------------------------------------------------------------------
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*/
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@ -453,13 +453,12 @@ static struct config_bool ConfigureNamesBool[] =
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true, NULL, NULL
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},
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{
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{"enable_constraint_exclusion", PGC_USERSET, QUERY_TUNING_OTHER,
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gettext_noop("Enables the planner's use of constraints in queries."),
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gettext_noop("Constraints will be examined to exclude tables "
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"that can be proven not to be required to produce "
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"a correct result for the query.")
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{"constraint_exclusion", PGC_USERSET, QUERY_TUNING_OTHER,
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gettext_noop("Enables the planner to use constraints to limit table access."),
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gettext_noop("This prevents table access if the table constraints "
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"guarantee that table access is necessary.")
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},
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&enable_constraint_exclusion,
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&constraint_exclusion,
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false, NULL, NULL
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},
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{
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@ -190,7 +190,7 @@
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# - Other Planner Options -
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#default_statistics_target = 10 # range 1-1000
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#enable_constraint_exclusion = off
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#constraint_exclusion = off
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#from_collapse_limit = 8
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#join_collapse_limit = 8 # 1 disables collapsing of explicit
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# JOINs
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.69 2005/07/23 21:05:48 tgl Exp $
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* $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.70 2005/08/22 17:35:03 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -49,7 +49,7 @@ extern bool enable_hashagg;
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extern bool enable_nestloop;
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extern bool enable_mergejoin;
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extern bool enable_hashjoin;
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extern bool enable_constraint_exclusion;
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extern bool constraint_exclusion;
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extern double clamp_row_est(double nrows);
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extern void cost_seqscan(Path *path, PlannerInfo *root, RelOptInfo *baserel);
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@ -1,8 +1,7 @@
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SELECT name, setting FROM pg_settings WHERE name LIKE 'enable%';
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name | setting
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-----------------------------+---------
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-------------------+---------
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enable_bitmapscan | on
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enable_constraint_exclusion | off
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enable_hashagg | on
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enable_hashjoin | on
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enable_indexscan | on
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@ -11,7 +10,7 @@ SELECT name, setting FROM pg_settings WHERE name LIKE 'enable%';
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enable_seqscan | on
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enable_sort | on
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enable_tidscan | on
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(10 rows)
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(9 rows)
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CREATE TABLE foo2(fooid int, f2 int);
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INSERT INTO foo2 VALUES(1, 11);
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