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Tom Lane f68970e33f Fix performance issue in new regex match-all detection code. Commit `824bf7190` introduced a new search of the NFAs generated by regex compilation. I failed to think hard about the performance characteristics of that search, with the predictable outcome that it's bad: weird regexes can trigger exponential search time. Worse, there's no check-for-interrupt in that code, so you can't even cancel the query if this happens. Fix by introducing memo-ization of the search results, so that any one NFA state need be examined in detail just once. This potentially uses a lot of memory, but we can bound the memory usage by putting a limit on the number of states for which we'll try to prove match-all-ness. That is sane because we already have a limit (DUPINF) on the maximum finite string length that a matchall regex can match; and patterns that involve much more than DUPINF states would probably exceed that limit anyway. Also, rearrange the logic so that we check the basic is-the-graph- all-RAINBOW-arcs property before we start the recursive search to determine path lengths. This will ensure that we fall out quickly whenever the NFA couldn't possibly be matchall. Also stick in a check-for-interrupt, just in case these measures don't completely eliminate the risk of slowness. Discussion: https://postgr.es/m/3483895.1619898362@sss.pgh.pa.us		2021-05-03 11:42:31 -04:00
config	Update config.guess and config.sub	2021-04-21 16:33:40 +02:00
contrib	Revert use singular for -1 (commits `9ee7d533da` and `5da9868ed9`	2021-05-01 10:42:44 -04:00
doc	Doc: add an example of a self-referential foreign key to ddl.sgml.	2021-04-30 15:37:56 -04:00
src	Fix performance issue in new regex match-all detection code.	2021-05-03 11:42:31 -04:00
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	2019-01-13 11:32:31 -08:00
.editorconfig	Add .editorconfig	2019-12-18 09:13:13 +01:00
.gitattributes	gitattributes: Add new file	2019-11-12 08:13:55 +01:00
.gitignore	Support for optimizing and emitting code in LLVM JIT provider.	2018-03-22 11:05:22 -07:00
COPYRIGHT	Update copyright for 2021	2021-01-02 13:06:25 -05:00
GNUmakefile.in	Make install-tests target work with vpath builds	2020-05-31 18:33:00 -04:00
HISTORY	Canonicalize some URLs	2020-02-10 20:47:50 +01:00
Makefile	Don't unset MAKEFLAGS in non-GNU Makefile.	2019-06-25 09:36:21 +12:00
README	Canonicalize some URLs	2020-02-10 20:47:50 +01:00
README.git	Canonicalize some URLs	2020-02-10 20:47:50 +01:00
aclocal.m4	Remove configure-time probe for DocBook DTD.	2020-11-30 15:24:13 -05:00
configure	Refactor HMAC implementations	2021-04-03 17:30:49 +09:00
configure.ac	Refactor HMAC implementations	2021-04-03 17:30:49 +09:00

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/.