From a7f49252d2476cc5996b1e9dbb253cdc521fbb7f Mon Sep 17 00:00:00 2001
From: Bruce Momjian
Date: Mon, 22 Aug 2005 17:35:03 +0000
Subject: enable_constraint_exclusion => constraint_exclusion
Also improve wording.
---
doc/src/FAQ/TODO.html | 4 ++--
doc/src/sgml/runtime.sgml | 26 +++++++++++++-------------
2 files changed, 15 insertions(+), 15 deletions(-)
(limited to 'doc/src')
diff --git a/doc/src/FAQ/TODO.html b/doc/src/FAQ/TODO.html
index a2b70a78bc9..edd160c3f77 100644
--- a/doc/src/FAQ/TODO.html
+++ b/doc/src/FAQ/TODO.html
@@ -355,7 +355,7 @@ first.
Add GUC to issue notice about queries that use unjoined tables
Allow EXPLAIN to identify tables that were skipped because of
- enable_constraint_exclusion
+ constraint_exclusion
Allow EXPLAIN output to be more easily processed by scripts
CREATE
@@ -694,7 +694,7 @@ first.
Allow the creation of indexes with mixed ascending/descending specifiers
-Fix incorrect rtree results due to wrong assumptions about "over"
operator semantics
- Allow enable_constraint_exclusion to work for UNIONs like it does for
+ Allow constraint_exclusion to work for UNIONs like it does for
inheritance, and allow it to work for UPDATE and DELETE queries
GIST
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 0966b5105e5..a699e0096b2 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
@@ -2352,24 +2352,24 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
-
- enable_constraint_exclusion (boolean)
+
+ constraint_exclusion (boolean)
constraint exclusion
- enable_constraint_exclusion> configuration parameter
+ constraint_exclusion> configuration parameter
- Enables or disables the query planner's use of table constraints.
- The default is off>.
+ Enables or disables the query planner's use of table constraints to
+ limit table access. The default is off>.
When this parameter is on>, the planner compares query
- conditions to table CHECK constraints, and omits scanning tables
- for which the conditions contradict the constraints. (Presently
+ conditions with table CHECK constraints, and omits scanning tables
+ where the conditions contradict the constraints. (Presently
this is done only for child tables of inheritance scans.) For
example:
@@ -2387,15 +2387,15 @@ SELECT * FROM parent WHERE key = 2400;
- Currently, enable_constraint_exclusion> defaults to
- off>, because it creates a risk of wrong answers when
- query plans are cached: if a table constraint is changed or dropped,
- the previously generated plan may now be wrong, and there is no
+ Currently, constraint_exclusion> defaults to
+ off>, because it risks incorrect results if
+ query plans are cached --- if a table constraint is changed or dropped,
+ the previously generated plan might now be wrong, and there is no
built-in mechanism to force re-planning. (This deficiency will
probably be addressed in a future
PostgreSQL release.) Another reason
for keeping it off is that the constraint checks are relatively
- expensive to make, and in many circumstances will yield no savings.
+ expensive, and in many circumstances will yield no savings.
It is recommended to turn this on only if you are actually using
partitioned tables designed to take advantage of the feature.
--
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