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Peter Geoghegan 6dd86c269d Fix nbtsort.c's page space accounting. 
Commit dd299df818, which made heap TID a tiebreaker nbtree index
column, introduced new rules on page space management to make suffix
truncation safe.  In general, suffix truncation needs to have a small
amount of extra space available on the new left page when splitting a
leaf page.  This is needed in case it turns out that truncation cannot
even "truncate away the heap TID column", resulting in a
larger-than-firstright leaf high key with an explicit heap TID
representation.

Despite all this, CREATE INDEX/nbtsort.c did not account for the
possible need for extra heap TID space on leaf pages when deciding
whether or not a new item could fit on current page.  This could lead to
"failed to add item to the index page" errors when CREATE
INDEX/nbtsort.c tried to finish off a leaf page that lacked space for a
larger-than-firstright leaf high key (it only had space for firstright
tuple, which was just short of what was needed following "truncation").

Several conditions needed to be met all at once for CREATE INDEX to
fail.  The problem was in the hard limit on what will fit on a page,
which tends to be masked by the soft fillfactor-wise limit.  The easiest
way to recreate the problem seems to be a CREATE INDEX on a low
cardinality text column, with tuples that are of non-uniform width,
using a fillfactor of 100.

To fix, bring nbtsort.c in line with nbtsplitloc.c, which already
pessimistically assumes that all leaf page splits will have high keys
that have a heap TID appended.

Reported-By: Andreas Joseph Krogh
Discussion: https://postgr.es/m/VisenaEmail.c5.3ee7fe277d514162.16a6d785bea@tc7-visena
2019-05-02 12:33:35 -07:00
config Update config.guess and config.sub 2019-04-27 14:25:00 +02:00
contrib Fix potential assertion failure when reindexing a pg_class index. 2019-04-29 19:42:08 -07:00
doc doc: clarify behavior of pg_upgrade's clone mode 2019-05-01 09:09:28 -04:00
src Fix nbtsort.c's page space accounting. 2019-05-02 12:33:35 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.gitattributes doc: Add some images 2019-03-27 23:10:23 +01:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Fix configure's AC_CHECK_DECLS tests to work correctly with clang. 2018-11-19 12:01:47 -05:00
configure Reorder configure tests for accept() in Windows 2019-03-04 14:42:12 -05:00
configure.in Fix PERMIT_DECLARATION_AFTER_STATEMENT initialization. 2019-02-16 13:12:28 -08:00
COPYRIGHT Update copyright for 2019 2019-01-02 12:44:25 -05:00
GNUmakefile.in Process EXTRA_INSTALL serially, during the first temp-install. 2018-12-31 13:54:38 -08:00
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 00:57:22 -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/.