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Tom Lane 6fbd5cce22 Fix performance hazard in REFRESH MATERIALIZED VIEW CONCURRENTLY. Jeff Janes discovered that commit `7ca25b7de` made one of the queries run by REFRESH MATERIALIZED VIEW CONCURRENTLY perform badly. The root cause is bad cardinality estimation for correlated quals, but a principled solution to that problem is some way off, especially since the planner lacks any statistics about whole-row variables. Moreover, in non-error cases this query produces no rows, meaning it must be run to completion; but use of LIMIT 1 encourages the planner to pick a fast-start, slow-completion plan, exactly not what we want. Remove the LIMIT clause, and instead rely on the count parameter we pass to SPI_execute() to prevent excess work if the query does return some rows. While we've heard no field reports of planner misbehavior with this query, it could be that people are having performance issues that haven't reached the level of pain needed to cause a bug report. In any case, that LIMIT clause can't possibly do anything helpful with any existing version of the planner, and it demonstrably can cause bad choices in some cases, so back-patch to 9.4 where the code was introduced. Thomas Munro Discussion: https://postgr.es/m/CAMkU=1z-JoGymHneGHar1cru4F1XDfHqJDzxP_CtK5cL3DOfmg@mail.gmail.com		2018-03-19 17:23:21 -04:00
config	Extend configure's __int128 test to check for a known gcc bug.	2018-01-18 11:09:44 -05:00
contrib	Add 'unit' parameter to ExplainProperty{Integer,Float}.	2018-03-16 23:16:04 -07:00
doc	Doc: note that statement-level view triggers require an INSTEAD OF trigger.	2018-03-18 15:10:28 -04:00
src	Fix performance hazard in REFRESH MATERIALIZED VIEW CONCURRENTLY.	2018-03-19 17:23:21 -04:00
.dir-locals.el
.gitattributes	Remove contrib/tsearch2.	2017-02-13 11:06:11 -05:00
.gitignore	Add lcov --initial	2017-09-29 08:54:34 -04:00
aclocal.m4	Make configure check for IPC::Run when --enable-tap-tests is specified.	2017-06-15 15:56:12 -04:00
configure	Tests for Kerberos/GSSAPI authentication	2018-03-06 10:57:36 -05:00
configure.in	Tests for Kerberos/GSSAPI authentication	2018-03-06 10:57:36 -05:00
COPYRIGHT	Update copyright for 2018	2018-01-02 23:30:12 -05:00
GNUmakefile.in	Have "make coverage" recurse into contrib as well	2016-09-05 18:44:36 -03:00
HISTORY	Change documentation references to PG website to use https: not http:	2017-05-20 21:50:47 -04:00
Makefile	Fix non-GNU makefiles for AIX make.	2017-11-30 00:57:22 -08:00
README	Change documentation references to PG website to use https: not http:	2017-05-20 21:50:47 -04:00
README.git	Change documentation references to PG website to use https: not http:	2017-05-20 21:50:47 -04:00

README

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.