rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
51,190 Commits 36 Branches 606 Tags 423 MiB
C 86%
PLpgSQL 5.5%
Perl 4.1%
Yacc 1.3%
Makefile 0.7%
Other 2.3%
Go to file
Peter Geoghegan 8523492d4e Remove tupgone special case from vacuumlazy.c. 
Retry the call to heap_prune_page() in rare cases where there is
disagreement between the heap_prune_page() call and the call to
HeapTupleSatisfiesVacuum() that immediately follows.  Disagreement is
possible when a concurrently-aborted transaction makes a tuple DEAD
during the tiny window between each step.  This was the only case where
a tuple considered DEAD by VACUUM still had storage following pruning.
VACUUM's definition of dead tuples is now uniformly simple and
unambiguous: dead tuples from each page are always LP_DEAD line pointers
that were encountered just after we performed pruning (and just before
we considered freezing remaining items with tuple storage).

Eliminating the tupgone=true special case enables INDEX_CLEANUP=off
style skipping of index vacuuming that takes place based on flexible,
dynamic criteria.  The INDEX_CLEANUP=off case had to know about skipping
indexes up-front before now, due to a subtle interaction with the
special case (see commit dd695979) -- this was a special case unto
itself.  Now there are no special cases.  And so now it won't matter
when or how we decide to skip index vacuuming: it won't affect how
pruning behaves, and it won't be affected by any of the implementation
details of pruning or freezing.

Also remove XLOG_HEAP2_CLEANUP_INFO records.  These are no longer
necessary because we now rely entirely on heap pruning taking care of
recovery conflicts.  There is no longer any need to generate recovery
conflicts for DEAD tuples that pruning just missed.  This also means
that heap vacuuming now uses exactly the same strategy for recovery
conflicts as index vacuuming always has: REDO routines never need to
process a latestRemovedXid from the WAL record, since earlier REDO of
the WAL record from pruning is sufficient in all cases.  The generic
XLOG_HEAP2_CLEAN record type is now split into two new record types to
reflect this new division (these are called XLOG_HEAP2_PRUNE and
XLOG_HEAP2_VACUUM).

Also stop acquiring a super-exclusive lock for heap pages when they're
vacuumed during VACUUM's second heap pass.  A regular exclusive lock is
enough.  This is correct because heap page vacuuming is now strictly a
matter of setting the LP_DEAD line pointers to LP_UNUSED.  No other
backend can have a pointer to a tuple located in a pinned buffer that
can be invalidated by a concurrent heap page vacuum operation.

Heap vacuuming can now be thought of as conceptually similar to index
vacuuming and conceptually dissimilar to heap pruning.  Heap pruning now
has sole responsibility for anything involving the logical contents of
the database (e.g., managing transaction status information, recovery
conflicts, considering what to do with HOT chains).  Index vacuuming and
heap vacuuming are now only concerned with recycling garbage items from
physical data structures that back the logical database.

Bump XLOG_PAGE_MAGIC due to pruning and heap page vacuum WAL record
changes.

Credit for the idea of retrying pruning a page to avoid the tupgone case
goes to Andres Freund.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznneCXTzuFmcwx_EyRQgfsfJAAsu+CsqRFmFXCAar=nJw@mail.gmail.com
 		2021-04-06 08:49:22 -07:00
config Update copyright for 2021 2021-01-02 13:06:25 -05:00
contrib psql: Show all query results by default 2021-04-06 17:10:24 +02:00
doc psql: Show all query results by default 2021-04-06 17:10:24 +02:00
src Remove tupgone special case from vacuumlazy.c. 2021-04-06 08:49:22 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.gitattributes gitattributes: Add new file 2019-11-12 08:13:55 +01:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in Make install-tests target work with vpath builds 2020-05-31 18:33:00 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00
aclocal.m4 Remove configure-time probe for DocBook DTD. 2020-11-30 15:24:13 -05:00
configure Refactor HMAC implementations 2021-04-03 17:30:49 +09:00
configure.ac Refactor HMAC implementations 2021-04-03 17:30:49 +09:00

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/.