Peter Eisentraut 78c887679d Add current substring regular expression syntax
SQL:1999 had syntax

    SUBSTRING(text FROM pattern FOR escapechar)

but this was replaced in SQL:2003 by the more clear

    SUBSTRING(text SIMILAR pattern ESCAPE escapechar)

but this was never implemented in PostgreSQL.  This patch adds that
new syntax as an alternative in the parser, and updates documentation
and tests to indicate that this is the preferred alternative now.

Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: https://www.postgresql.org/message-id/flat/a15db31c-d0f8-8ce0-9039-578a31758adb%402ndquadrant.com
2020-06-29 11:05:00 +02:00
..
2020-01-01 12:21:45 -05:00
2020-03-30 19:17:23 +03:00
2020-01-01 12:21:45 -05:00
2020-06-09 10:41:41 +02:00
2020-05-21 08:31:16 -07:00
2020-04-13 11:55:45 -04:00

The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.