database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-31 22:04:40 +03:00
Code Activity

Make WAL segment size configurable at initdb time.

Browse Source 
For performance reasons a larger segment size than the default 16MB
can be useful. A larger segment size has two main benefits: Firstly,
in setups using archiving, it makes it easier to write scripts that
can keep up with higher amounts of WAL, secondly, the WAL has to be
written and synced to disk less frequently.

But at the same time large segment size are disadvantageous for
smaller databases. So far the segment size had to be configured at
compile time, often making it unrealistic to choose one fitting to a
particularly load. Therefore change it to a initdb time setting.

This includes a breaking changes to the xlogreader.h API, which now
requires the current segment size to be configured.  For that and
similar reasons a number of binaries had to be taught how to recognize
the current segment size.

Author: Beena Emerson, editorialized by Andres Freund
Reviewed-By: Andres Freund, David Steele, Kuntal Ghosh, Michael
    Paquier, Peter Eisentraut, Robert Hass, Tushar Ahuja
Discussion: https://postgr.es/m/CAOG9ApEAcQ--1ieKbhFzXSQPw_YLmepaa4hNdnY5+ZULpt81Mw@mail.gmail.com
This commit is contained in:
Andres Freund
2017-09-19 22:03:48 -07:00
parent 5ada1fcd0c
commit fc49e24fa6
46 changed files with 898 additions and 501 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
configure.in
View File

@ -343,37 +343,6 @@ AC_DEFINE_UNQUOTED([XLOG_BLCKSZ], ${XLOG_BLCKSZ}, [
Changing XLOG_BLCKSZ requires an initdb.
])
#
# WAL segment size
#
AC_MSG_CHECKING([for WAL segment size])
PGAC_ARG_REQ(with, wal-segsize, [SEGSIZE], [set WAL segment size in MB [16]],
[wal_segsize=$withval],
[wal_segsize=16])
case ${wal_segsize} in
1) ;;
2) ;;
4) ;;
8) ;;
16) ;;
32) ;;
64) ;;
128) ;;
256) ;;
512) ;;
1024) ;;
*) AC_MSG_ERROR([Invalid WAL segment size. Allowed values are 1,2,4,8,16,32,64,128,256,512,1024.])
esac
AC_MSG_RESULT([${wal_segsize}MB])
AC_DEFINE_UNQUOTED([XLOG_SEG_SIZE], [(${wal_segsize} * 1024 * 1024)], [
XLOG_SEG_SIZE is the size of a single WAL file. This must be a power of 2
and larger than XLOG_BLCKSZ (preferably, a great deal larger than
XLOG_BLCKSZ).
Changing XLOG_SEG_SIZE requires an initdb.
])
#
# C compiler
#