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Tom Lane ddcc582a4f Fix pg_dump's handling of circular dependencies in views. This is a back-patch of the v10 commit `d8c05aff5`. The motivation for doing this now is that we received a complaint that a view with a circular dependency is dumped with an extra bogus command "ALTER TABLE ONLY myview REPLICA IDENTITY NOTHING", because pg_dump forgets that it's a view not a table, and the relreplident value stored for a view is that. So you'll get an error message during restore even if not using --clean; this would break pg_upgrade for example. While that could be handled with a one-line patch, it seems better to back-patch `d8c05aff5`, since that produces cleaner more future-proof output and fixes an additional bug. Per gripe from Alex Williams. Back-patch to 9.4-9.6 (even if 9.3 were still in support, it hasn't got REPLICA IDENTITY so no bug). Discussion: https://postgr.es/m/NFqxoEi7-8Rw9OW0f-GwHcjvS2I4YQXov4g9OoWv3i7lVOZdLWkAWl9jQQqwEaUq6WV0vdobromhW82e8y5I0_59yZTXcZnXsrmFuldlmZc=@protonmail.com Original commit message follows: pg_dump's traditional solution for breaking a circular dependency involving a view was to create the view with CREATE TABLE and then later issue CREATE RULE "_RETURN" ... to convert the table to a view, relying on the backend's very very ancient code that supports making views that way. We've wanted to get rid of that kluge for a long time, but the thing that finally motivates doing something about it is the recognition that this method fails with the --clean option, because it leads to issuing DROP RULE "_RETURN" followed by DROP TABLE --- and the backend won't let you drop a view's _RETURN rule. Instead, let's break circular dependencies by initially creating the view using CREATE VIEW AS SELECT NULL::columntype AS columnname, ... (so that it has the right column names and types to support external references, but no dependencies beyond the column data types), and then later dumping the ON SELECT rule using the spelling CREATE OR REPLACE VIEW. This method wasn't available when this code was originally written, but it's been possible since PG 7.3, so it seems fine to start relying on it now. To solve the --clean problem, make the dropStmt for an ON SELECT rule be CREATE OR REPLACE VIEW with the same dummy target list as above. In this way, during the DROP phase, we first reduce the view to have no extra dependencies, and then we can drop it entirely when we've gotten rid of whatever had a circular dependency on it. (Note: this should work adequately well with the --if-exists option, since the CREATE OR REPLACE VIEW will go through whether the view exists or not. It could fail if the view exists with a conflicting column set, but we don't really support --clean against a non-matching database anyway.) This allows cleaning up some other kluges inside pg_dump, notably that we don't need a notion of reloptions attached to a rule anymore. Although this is a bug fix, commit to HEAD only for now. The problem's existed for a long time and we've had relatively few complaints, so it doesn't really seem worth taking risks to fix it in the back branches. We might revisit that choice if no problems emerge. Discussion: <19092.1479325184@sss.pgh.pa.us>		2019-10-26 17:37:20 -04:00
config	configure: Update python search order	2019-09-08 13:45:13 -04:00
contrib	Add missing include to pg_upgrade/version.c	2019-10-16 16:28:48 +02:00
doc	docs: fix wording of REFRESH CONCURRENTLY manual page	2019-10-23 20:29:02 -04:00
src	Fix pg_dump's handling of circular dependencies in views.	2019-10-26 17:37:20 -04:00
.dir-locals.el	Update Emacs configuration	2013-08-13 20:08:44 -04:00
.gitattributes	gitattributes: Ignore time zone data files for whitespace checks	2014-07-22 00:12:28 -04:00
.gitignore	Add /config.cache to .gitignore in back branches	2017-02-25 13:04:22 -05:00
aclocal.m4	Back-patch updated thread flags tests into 9.4 and 9.5.	2018-11-19 14:24:52 -05:00
configure	Use CFLAGS_SL while probing linkability of libperl.	2019-10-21 13:52:26 -04:00
configure.in	Use CFLAGS_SL while probing linkability of libperl.	2019-10-21 13:52:26 -04:00
COPYRIGHT	Update copyright for 2019	2019-01-02 12:44:25 -05:00
GNUmakefile.in	Add TAP tests for client programs	2014-04-14 21:33:46 -04:00
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 00:57:32 -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/.