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Tom Lane d5e8930f50 pg_dump: minor performance improvements from eliminating sub-SELECTs.
Get rid of the "username_subquery" mechanism in favor of doing
local lookups of role names from role OIDs.  The PG backend isn't
terribly smart about scalar SubLinks in SELECT output lists,
so this offers a small performance improvement, at least in
installations with more than a couple of users.  In any case
the old method didn't make for particularly readable SQL code.

While at it, I removed the various custom warning messages about
failing to find an object's owner, in favor of just fatal'ing
in the local lookup function.  AFAIK there is no reason any
longer to treat that as anything but a catalog-corruption case,
and certainly no reason to make translators deal with a dozen
different messages where one would do.  (If it turns out that
fatal() is indeed a bad idea, we can back off to issuing
pg_log_warning() and returning an empty string, resulting in
the same behavior as before, except more consistent.)

Also drop an entirely unnecessary sub-SELECT to check on the
pg_depend status of a sequence relation: we already have a
LEFT JOIN to fetch the row of interest in the FROM clause.

Discussion: https://postgr.es/m/2460369.1640903318@sss.pgh.pa.us
2021-12-31 11:39:26 -05:00
2021-11-22 15:57:31 -05:00
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2020-02-10 20:47:50 +01:00

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/.
Description
Зеркало официального репозитория PostgreSQL GIT
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