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Tom Lane 8004953b5a Speed up ruleutils' name de-duplication code, and fix overlength-name case. 
Since commit 11e131854f, ruleutils.c has
attempted to ensure that each RTE in a query or plan tree has a unique
alias name.  However, the code that was added for this could be quite slow,
even as bad as O(N^3) if N identical RTE names must be replaced, as noted
by Jeff Janes.  Improve matters by building a transient hash table within
set_rtable_names.  The hash table in itself reduces the cost of detecting a
duplicate from O(N) to O(1), and we can save another factor of N by storing
the number of de-duplicated names already created for each entry, so that
we don't have to re-try names already created.  This way is probably a bit
slower overall for small range tables, but almost by definition, such cases
should not be a performance problem.

In principle the same problem applies to the column-name-de-duplication
code; but in practice that seems to be less of a problem, first because
N is limited since we don't support extremely wide tables, and second
because duplicate column names within an RTE are fairly rare, so that in
practice the cost is more like O(N^2) not O(N^3).  It would be very much
messier to fix the column-name code, so for now I've left that alone.

An independent problem in the same area was that the de-duplication code
paid no attention to the identifier length limit, and would happily produce
identifiers that were longer than NAMEDATALEN and wouldn't be unique after
truncation to NAMEDATALEN.  This could result in dump/reload failures, or
perhaps even views that silently behaved differently than before.  We can
fix that by shortening the base name as needed.  Fix it for both the
relation and column name cases.

In passing, check for interrupts in set_rtable_names, just in case it's
still slow enough to be an issue.

Back-patch to 9.3 where this code was introduced.
 		2015-11-16 13:45:17 -05:00
config Add BSWAP64 macro. 2015-10-08 13:01:36 -04:00
contrib Add regression tests for remote execution of extension operators/functions. 2015-11-04 12:03:30 -05:00
doc Correct sepgsql docs with regard to RLS 2015-11-13 11:06:38 -05:00
src Speed up ruleutils' name de-duplication code, and fix overlength-name case. 2015-11-16 13:45:17 -05:00
.dir-locals.el emacs: Set indent-tabs-mode in perl-mode 2015-04-12 23:53:23 -04:00
.gitattributes Add functions for dealing with PGP armor header lines to pgcrypto. 2014-10-01 16:03:39 +03:00
.gitignore Add .gitignore entries for AIX-specific intermediate build artifacts. 2015-07-08 20:44:22 -04:00
COPYRIGHT Update copyright for 2015 2015-01-06 11:43:47 -05:00
GNUmakefile.in Fix distclean/maintainer-clean targets to remove top-level tmp_install dir. 2015-05-13 18:48:05 -04:00
HISTORY Improve text of stub HISTORY file. 2014-02-12 18:16:17 -05:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:04 -05:00
README.git Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:04 -05:00
aclocal.m4 Replace our hacked version of ax_pthread.m4 with latest upstream version. 2015-07-08 20:36:06 +03:00
configure Add BSWAP64 macro. 2015-10-08 13:01:36 -04:00
configure.in Add BSWAP64 macro. 2015-10-08 13:01:36 -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:

	http://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
http://www.postgresql.org/download/.  For more information look at our
web site located at http://www.postgresql.org/.