Merge lp:~hrvojem/percona-server/bug930571-5.1 into lp:percona-server/5.1

Proposed by Hrvoje Matijakovic on 2012-03-12
Status: Merged
Approved by: Stewart Smith on 2012-04-02
Approved revision: no longer in the source branch.
Merged at revision: 432
Proposed branch: lp:~hrvojem/percona-server/bug930571-5.1
Merge into: lp:percona-server/5.1
Diff against target: 335 lines (+149/-20)
15 files modified
doc/source/compatibility.rst (+25/-0)
doc/source/diagnostics/misc_info_schema_tables.rst (+2/-0)
doc/source/index.rst (+2/-0)
doc/source/management/innodb_fake_changes.rst (+7/-1)
doc/source/performance/innodb_fast_checksum.rst (+1/-2)
doc/source/release-notes/Percona-Server-1.0.3-6.rst (+1/-1)
doc/source/release-notes/Percona-Server-1.0.4-8.rst (+5/-5)
doc/source/release-notes/Percona-Server-1.0.6-9.rst (+5/-5)
doc/source/release-notes/Percona-Server-5.1.47-rel11.1.rst (+1/-1)
doc/source/release-notes/Percona-Server-5.1.52-rel11.6.rst (+1/-1)
doc/source/release-notes/Percona-Server-5.1.53-12.4.rst (+1/-1)
doc/source/release-notes/Percona-Server-5.1.58-12.9.rst (+2/-2)
doc/source/reliability/innodb_recovery_update_relay_log.rst (+80/-0)
doc/source/scalability/innodb_expand_undo_slots.rst (+1/-1)
doc/source/scalability/innodb_io.rst (+15/-0)
To merge this branch: bzr merge lp:~hrvojem/percona-server/bug930571-5.1
Reviewer Review Type Date Requested Status
Stewart Smith (community) 2012-03-12 Approve on 2012-04-02
Alexey Kopytov 2012-03-27 Pending
Review via email: mp+97009@code.launchpad.net
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Stewart Smith (stewart) wrote :

I think the following could be fixed, although it's not going to stop me merging this tree as is:

In "Relocation of the doublewrite buffer", "turned on/off without breaking the compatibility." can drop the "the".

In "doc/source/diagnostics/misc_info_schema_tables.rst", "Only the temporary tables that were explicitly created with `CREATE TEMPORARY TABLE` or `ALTER TABLE` are shown, and not the ones created to process complex queries." should drop the first "the" and "to process complex queries" should be replaced with "during query execution".

In "innodb_fake_changes.rst", "Restarting a slave server in a replication environment or setting up new slave server can cause a replication reads slower. This is happening because replication in |MySQL| is single-threaded and because it needs to read the data before it can execute the queries. The process can be speeded up by having prefetch threads to warm the server: replay statements and then rollback at commit." should be "Replication in |MySQL| is single-threaded and because it needs to read the data before it can execute the queries, this can decrease performance when the full data set is not already in the buffer pool. The fake changes feature allows a process to replay a set of operations against a replication slave to warm the buffer pool for the replication apply thread."

review: Approve
429. By Hrvoje Matijakovic on 2012-04-02

* bug fixes for: Bug #787916 Bug #914289 Bug #930571
                Bug #944390 Bug #889112 Bug #949030
* cleaned up older release notes and fixed some links and typos

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=== added file 'doc/source/compatibility.rst'
--- doc/source/compatibility.rst 1970-01-01 00:00:00 +0000
+++ doc/source/compatibility.rst 2012-04-02 07:10:25 +0000
@@ -0,0 +1,25 @@
1.. _compatibility:
2
3==============================================================
4Options that make XtraDB tablespaces not compatible with MySQL
5==============================================================
6
7Expanded undo slots
8===================
9
10Enabling :variable:`innodb_extra_undoslots` breaks compatibility with other programs. Specifically, it makes the datafiles unusable for ibbackup or for a MySQL server that is not run with this option.
11
12Fast checksums
13==============
14
15Enabling :variable:`innodb_fast_checksum` will use more CPU-efficient algorithm, based on 4-byte words which can be beneficial for some workloads. Once enabled, turning it off will require table to be dump/imported again, since it will fail to start on data files created when :variable:`innodb_fast_checksums` was enabled.
16
17Page sizes other than 16KiB
18===========================
19
20This is controlled by variable :variable:`innodb_page_size`. Changing the page size for an existing database is not supported. Table will need to be dumped/imported again if compatibility with |MySQL| is required.
21
22Relocation of the doublewrite buffer
23====================================
24
25Variable :variable:`innodb_doublewrite_file` provides an option to put the buffer on a dedicated disk in order to parallelize I/O activity on the buffer and on the tablespace. Only in case of crash recovery this variable cannot be changed, in all other cases it can be turned on/off without breaking compatibility.
026
=== modified file 'doc/source/diagnostics/misc_info_schema_tables.rst'
--- doc/source/diagnostics/misc_info_schema_tables.rst 2011-09-20 06:59:03 +0000
+++ doc/source/diagnostics/misc_info_schema_tables.rst 2012-04-02 07:10:25 +0000
@@ -98,6 +98,8 @@
98Temporary tables98Temporary tables
99================99================
100100
101 Only temporary tables that were explicitly created with `CREATE TEMPORARY TABLE` or `ALTER TABLE` are shown, and not the ones created during query execution.
102
101.. table:: INFORMATION_SCHEMA.GLOBAL_TEMPORARY_TABLES103.. table:: INFORMATION_SCHEMA.GLOBAL_TEMPORARY_TABLES
102104
103 :column SESSION_ID: |MySQL| connection id105 :column SESSION_ID: |MySQL| connection id
104106
=== modified file 'doc/source/index.rst'
--- doc/source/index.rst 2012-03-16 09:07:44 +0000
+++ doc/source/index.rst 2012-04-02 07:10:25 +0000
@@ -104,6 +104,7 @@
104 reliability/log_connection_error104 reliability/log_connection_error
105 reliability/error_pad105 reliability/error_pad
106 reliability/innodb_corrupt_table_action106 reliability/innodb_corrupt_table_action
107 reliability/innodb_recovery_update_relay_log
107 reliability/show_slave_status_nolock108 reliability/show_slave_status_nolock
108109
109Management Improvements110Management Improvements
@@ -163,6 +164,7 @@
163 development164 development
164 trademark-policy165 trademark-policy
165 faq166 faq
167 compatibility
166 release-notes/release-notes_index168 release-notes/release-notes_index
167 glossary169 glossary
168170
169171
=== modified file 'doc/source/management/innodb_fake_changes.rst'
--- doc/source/management/innodb_fake_changes.rst 2011-10-14 02:52:34 +0000
+++ doc/source/management/innodb_fake_changes.rst 2012-04-02 07:10:25 +0000
@@ -4,7 +4,7 @@
4 Support for Fake Changes4 Support for Fake Changes
5==========================5==========================
66
7When restarting a slave server in a replication environment, the process can be speed up by having prefetch threads to warm the server: replay statements and then rollback at commit.7Replication in |MySQL| is single-threaded and because it needs to read the data before it can execute the queries, this can decrease performance when the full data set is not already in the buffer pool. The fake changes feature allows a process to replay a set of operations against a replication slave to warm the buffer pool for the replication apply thread.
88
9That makes prefetch simple but has high overhead from locking rows only to undo changes at rollback.9That makes prefetch simple but has high overhead from locking rows only to undo changes at rollback.
1010
@@ -63,3 +63,9 @@
63 * It will not prefetch allocate/free, split/merge, ``INODE``, ``XDES`` or other management pages. The same is for extern pages, i.e. large ``BLOB`` s).63 * It will not prefetch allocate/free, split/merge, ``INODE``, ``XDES`` or other management pages. The same is for extern pages, i.e. large ``BLOB`` s).
6464
65 * Foreign key constraints are checked (for causing IO), but passed always.65 * Foreign key constraints are checked (for causing IO), but passed always.
66
67Related Reading
68===============
69
70 * `on MySQL replication prefetching <http://dom.as/2011/12/03/replication-prefetching/>`_
71
6672
=== modified file 'doc/source/performance/innodb_fast_checksum.rst'
--- doc/source/performance/innodb_fast_checksum.rst 2011-10-07 00:55:06 +0000
+++ doc/source/performance/innodb_fast_checksum.rst 2012-04-02 07:10:25 +0000
@@ -10,8 +10,7 @@
1010
11The original algorithm is checked after the new one, so you can have data pages with old checksums and data pages with new checksums. However in this case, you may experience slow reads from pages having old checksums. If you want to have the entire benefit of this change, you will need to recreate all your |InnoDB| tables, for instance by dumping and reloading all |InnoDB| tables.11The original algorithm is checked after the new one, so you can have data pages with old checksums and data pages with new checksums. However in this case, you may experience slow reads from pages having old checksums. If you want to have the entire benefit of this change, you will need to recreate all your |InnoDB| tables, for instance by dumping and reloading all |InnoDB| tables.
1212
13Once enabled, turning it off will require table re-creation as well, since it will fail to start on data files created when ``innodb_fast_checksums`` was enabled.13Once enabled, turning it off will require table(s) to be dump/imported, since it will fail to start on data files created when ``innodb_fast_checksums`` was enabled. In this case ALTER TABLE won't work due to its implementation.
14
1514
16System Variables15System Variables
17================16================
1817
=== modified file 'doc/source/release-notes/Percona-Server-1.0.3-6.rst'
--- doc/source/release-notes/Percona-Server-1.0.3-6.rst 2011-10-07 00:55:06 +0000
+++ doc/source/release-notes/Percona-Server-1.0.3-6.rst 2012-04-02 07:10:25 +0000
@@ -27,7 +27,7 @@
27Fixed bugs27Fixed bugs
28==========28==========
2929
30 * |MySQL| Bug: ``#39793 <http://bugs.mysql.com/39793>`_: Foreign keys not constructed when column has a ``#`` in a comment or default value30 * |MySQL| Bug: `#39793 <http://bugs.mysql.com/39793>`_: Foreign keys not constructed when column has a ``#`` in a comment or default value
3131
32 * Bug :bug:`395784` in Percona-XtraDB: ``main.innodb_xtradb_bug317074 internal check fails on 5.1.36``32 * Bug :bug:`395784` in Percona-XtraDB: ``main.innodb_xtradb_bug317074 internal check fails on 5.1.36``
3333
3434
=== modified file 'doc/source/release-notes/Percona-Server-1.0.4-8.rst'
--- doc/source/release-notes/Percona-Server-1.0.4-8.rst 2011-09-26 22:00:30 +0000
+++ doc/source/release-notes/Percona-Server-1.0.4-8.rst 2012-04-02 07:10:25 +0000
@@ -13,10 +13,10 @@
13Fixed bugs:13Fixed bugs:
14===========14===========
1515
16 * [[https://bugs.launchpad.net/percona-xtradb/+bug/413858|Bugs#413858: Crash from failed assertion in dict0dict.c]]16 * :bug:`413858`: Crash from failed assertion in dict0dict.c]]
1717
18 * [[https://bugs.launchpad.net/percona-xtradb/+bug/417751|Bug#417751: |XtraDB| crashes on startup on windows]]18 * :bug:`417751`: |XtraDB| crashes on startup on windows]]
1919
20 * [[https://code.launchpad.net/~percona-dev/percona-xtradb/fix-import-extern-pages|fix-import-extern-pages]]20 * `fix-import-extern-pages <https://code.launchpad.net/~percona-dev/percona-xtradb/fix-import-extern-pages>`_
2121
22 * Number of |MySQL|-tests are fixed22 * Number of |MySQL|-tests are fixed
2323
=== modified file 'doc/source/release-notes/Percona-Server-1.0.6-9.rst'
--- doc/source/release-notes/Percona-Server-1.0.6-9.rst 2011-09-26 22:00:30 +0000
+++ doc/source/release-notes/Percona-Server-1.0.6-9.rst 2012-04-02 07:10:25 +0000
@@ -28,8 +28,8 @@
2828
29Fixed bugs:29Fixed bugs:
3030
31 * Bug :bug:`488315`: rename columns and add unique index cause serious inconsistent with :command:`mysqld`31 * Bug :bug:`488315`: rename columns and add unique index cause serious inconsistent with :command:`mysqld`.
3232
33 * Bug :bug:495342]]: “MySQL 5.1.41 + InnoDB 1.0.6 + XtraDB patches extensions-1.0.6, rev. 127 fails to compile on OpenSolaris”33 * Bug :bug:`495342`: MySQL 5.1.41 + InnoDB 1.0.6 + XtraDB patches extensions-1.0.6, rev. 127 fails to compile on OpenSolaris.
3434
35 * |MySQL| bug `#47621 <http://bugs.mysql.com/47621>`_: change the fix of http://bugs.mysql.com/47621 more reasonable35 * |MySQL| bug `#47621 <http://bugs.mysql.com/47621>`_: change the fix of http://bugs.mysql.com/47621 more reasonable.
3636
=== modified file 'doc/source/release-notes/Percona-Server-5.1.47-rel11.1.rst'
--- doc/source/release-notes/Percona-Server-5.1.47-rel11.1.rst 2011-09-26 22:00:30 +0000
+++ doc/source/release-notes/Percona-Server-5.1.47-rel11.1.rst 2012-04-02 07:10:25 +0000
@@ -36,7 +36,7 @@
3636
37 * :bug:`580324` - Security bug in upstream 37 * :bug:`580324` - Security bug in upstream
3838
39 * :bug:`586579` -|Percona Server| 11 fails to compile with ``CFLAGS=-DUNIV_DEBUG`` 39 * :bug:`586579` - |Percona Server| 11 fails to compile with ``CFLAGS=-DUNIV_DEBUG``
4040
41 * :bug:`569156` - CentOS 5: ``mysql-server`` conflicts with ``mysql-server`` 41 * :bug:`569156` - CentOS 5: ``mysql-server`` conflicts with ``mysql-server``
4242
4343
=== modified file 'doc/source/release-notes/Percona-Server-5.1.52-rel11.6.rst'
--- doc/source/release-notes/Percona-Server-5.1.52-rel11.6.rst 2011-09-26 22:00:30 +0000
+++ doc/source/release-notes/Percona-Server-5.1.52-rel11.6.rst 2012-04-02 07:10:25 +0000
@@ -18,7 +18,7 @@
18Bugs Fixed18Bugs Fixed
19===========19===========
2020
21 * Bug :bug:`671764` - ``innochecksum`` wasn``t distributed with RPM and .DEB packages (Aleksandr Kuzminsky)21 * Bug :bug:`671764` - ``innochecksum`` wasn't distributed with RPM and .DEB packages (Aleksandr Kuzminsky)
2222
23 * Bug :bug:`673426` - Use of some system variables as command-line options caused a crash or undefined behavior. (*Oleg Tsarev*)23 * Bug :bug:`673426` - Use of some system variables as command-line options caused a crash or undefined behavior. (*Oleg Tsarev*)
2424
2525
=== modified file 'doc/source/release-notes/Percona-Server-5.1.53-12.4.rst'
--- doc/source/release-notes/Percona-Server-5.1.53-12.4.rst 2011-10-07 00:55:06 +0000
+++ doc/source/release-notes/Percona-Server-5.1.53-12.4.rst 2012-04-02 07:10:25 +0000
@@ -45,7 +45,7 @@
4545
46 * Bug :bug:`677407` - The ``innodb_information_schema`` test could fail sporadically due to flawed logic in the ``INFORMATION_SCHEMA.INNODB_LOCKS`` caching mechanism. (contributed by *Kristian Nielsen*) (*Alexey Kopytov*)46 * Bug :bug:`677407` - The ``innodb_information_schema`` test could fail sporadically due to flawed logic in the ``INFORMATION_SCHEMA.INNODB_LOCKS`` caching mechanism. (contributed by *Kristian Nielsen*) (*Alexey Kopytov*)
4747
48 * Bug :bug:`681486` - A dependency between Debian packages ``lib|MySQL|client16`` and ``percona-server-common`` was removed. (*Aleksandr Kuzminsky*)48 * Bug :bug:`681486` - A dependency between Debian packages ``libmysqlclient16`` and ``percona-server-common`` was removed. (*Aleksandr Kuzminsky*)
4949
50 * Bug :bug:`693815` - The test ``percona_innodb_buffer_pool_shm`` was failing. It should be run with the ``--big-test`` option. As the buffer pool size used in the test is 128M, the shared memory segment should be increased appropriately in order to run the test successfully.50 * Bug :bug:`693815` - The test ``percona_innodb_buffer_pool_shm`` was failing. It should be run with the ``--big-test`` option. As the buffer pool size used in the test is 128M, the shared memory segment should be increased appropriately in order to run the test successfully.
5151
5252
=== modified file 'doc/source/release-notes/Percona-Server-5.1.58-12.9.rst'
--- doc/source/release-notes/Percona-Server-5.1.58-12.9.rst 2011-12-03 02:46:52 +0000
+++ doc/source/release-notes/Percona-Server-5.1.58-12.9.rst 2012-04-02 07:10:25 +0000
@@ -23,7 +23,7 @@
2323
24Two new collations, ``utf8_general50_ci`` and ``ucs2_general50_ci``, have been to improve compatibility for those upgrading from |MySQL| 5.0 or 5.1 prior to version 5.1.24.24Two new collations, ``utf8_general50_ci`` and ``ucs2_general50_ci``, have been to improve compatibility for those upgrading from |MySQL| 5.0 or 5.1 prior to version 5.1.24.
2525
26A fix for a |MySQL| bug ([[`#27877 <http://bugs.mysql.com/bug.php?id=27877>`) introduced an incompatible change in collations in |MySQL| 5.1.24. If the following collations were used:26A fix for a |MySQL| bug `#27877 <http://bugs.mysql.com/bug.php?id=27877>`_ introduced an incompatible change in collations in |MySQL| 5.1.24. If the following collations were used:
2727
28 * ``utf8_general_ci`` 28 * ``utf8_general_ci``
29 * ``ucs2_general_ci``29 * ``ucs2_general_ci``
@@ -37,7 +37,7 @@
37 * ``utf8_general_ci`` to ``utf8_general50_ci``, and 37 * ``utf8_general_ci`` to ``utf8_general50_ci``, and
38 * ``ucs2_general_ci`` to ``ucs2_general50_ci``.38 * ``ucs2_general_ci`` to ``ucs2_general50_ci``.
3939
40Blueprint:[[https://blueprints.launchpad.net/percona-server/+spec/utf8-general50-ci-5.1|utf8-general50-ci-5.1]] (*Alexey Kopytov*).40Blueprint: `utf8-general50-ci-5.1 <https://blueprints.launchpad.net/percona-server/+spec/utf8-general50-ci-5.1>`_ (*Alexey Kopytov*).
4141
42SHM Buffer Pool has been removed42SHM Buffer Pool has been removed
43--------------------------------43--------------------------------
4444
=== added file 'doc/source/reliability/innodb_recovery_update_relay_log.rst'
--- doc/source/reliability/innodb_recovery_update_relay_log.rst 1970-01-01 00:00:00 +0000
+++ doc/source/reliability/innodb_recovery_update_relay_log.rst 2012-04-02 07:10:25 +0000
@@ -0,0 +1,80 @@
1.. _innodb_recovery_update_relay_log_page:
2
3=============================
4 Crash-Resistant Replication
5=============================
6
7This feature makes replication much more reliable after a crash by making the replica's position relative to the master transactional.
8
9|MySQL| replication normally stores its position in a file that is neither durable nor consistent. Thus, if the replica crashes, it can re-execute committed transactions. This usually causes replication to fail, potentially forcing the replica's data to be re-initialized from the master or from a recent backup.
10
11The improvement in |Percona Server| makes |InnoDB| store the replication position transactionally, and overwrite the usual relay-log.info file upon recovery, so replication restarts from the correct position and does not try to re-execute committed transactions. This change greatly improves the durability of |MySQL| replication. It can be set to activate automatically, so replication “just works” and no intervention is necessary after a crash.
12
13
14Restrictions
15============
16
17When :variable:`innodb_overwrite_relay_log_info` is enabled, you should only update |InnoDB| / |XtraDB| tables, not |MyISAM| tables or other storage engines.
18You should not use relay or binary log filenames longer than 480 characters (normal: up to 512). If longer, the replication position information is not recorded in |InnoDB|.
19
20Example Server Error Log Output
21===============================
22
23Upon crash recovery, the error log on a replica will show information similar to the following: ::
24
25 InnoDB: Starting crash recovery.
26 ....
27 InnoDB: Apply batch completed
28 InnoDB: In a MySQL replication slave the last master binlog file
29 InnoDB: position 0 468, file name gauntlet3-bin.000015
30 InnoDB: and relay log file
31 InnoDB: position 0 617, file name ./gauntlet3-relay-bin.000111
32
33If this feature is enabled, the output will look like the following, with additional lines prefixed with a ``+`` symbol: ::
34
35 ....
36 + InnoDB: Warning: innodb_overwrite_relay_log_info is enabled. Updates of other storage engines may have problem of consistency.
37 + InnoDB: relay-log.info is detected.
38 + InnoDB: relay log: position 429, file name ./gauntlet3-relay-bin.000111
39 + InnoDB: master log: position 280, file name gauntlet3-bin.000015
40 ....
41 InnoDB: Starting crash recovery.
42 ....
43 InnoDB: Apply batch completed
44 + InnoDB: In a MySQL replication slave the last master binlog file
45 + InnoDB: position 0 468, file name gauntlet3-bin.000015
46 + InnoDB: and relay log file
47 + InnoDB: position 0 617, file name ./gauntlet3-relay-bin.000111
48 090205 17:41:31 InnoDB Plugin 1.0.2-3 started; log sequence number 57933
49 + InnoDB: relay-log.info have been overwritten.
50 ....
51 090205 17:41:31 [Note] Slave SQL thread initialized, starting replication in log ``gauntlet3-bin.000015`` at position 468, relay log ``./gauntlet3-relay-bin.000111`` position: 617
52
53In this case, the master log position was overwritten to 468 from 280, so replication will start at position 468 and not repeat the transaction beginning at 280.
54
55System Variables
56================
57
58One new system variable was introduced by this feature.
59
60.. variable:: innodb_overwrite_relay_log_info
61
62 :version 5.5.10-20.1: Renamed.
63 :cli: Yes
64 :conf: Yes
65 :scope: Global
66 :dyn: No
67 :vartype: BOOLEAN
68 :default: FALSE
69 :range: TRUE/FALSE
70
71If set to true, |InnoDB| overwrites :file:`relay-log.info` at crash recovery when the information is different from the record in |InnoDB|.
72
73Other Reading
74=============
75
76 * Another solution for |MySQL| 5.0 is `Google's transactional replication feature <http://code.google.com/p/google-mysql-tools/wiki/TransactionalReplication>`_, but it had some problems and bugs.
77
78 * `Related bug (fixed and re-implemented in this feature) <http://bugs.|MySQL|.com/bug.php?id=34058>`_
79
80 * `A blog post explaining how this feature makes replication more reliable <http://www.|MySQL|performanceblog.com/2009/03/04/making-replication-a-bit-more-reliable/>`_
081
=== modified file 'doc/source/scalability/innodb_expand_undo_slots.rst'
--- doc/source/scalability/innodb_expand_undo_slots.rst 2011-10-07 00:55:06 +0000
+++ doc/source/scalability/innodb_expand_undo_slots.rst 2012-04-02 07:10:25 +0000
@@ -4,7 +4,7 @@
4More Concurrent Transactions Available4More Concurrent Transactions Available
5======================================5======================================
66
7|InnoDB| provides a fixed number of 1024 undo slots in its rollback segment, leaving room for 1024 transactions to run in parallel. If all the slots are used any new transaction will fail until a slot is freed, which can cause st:range: behaviors. This change provides a variable to expand the number of undo slots, up to 4072.7|InnoDB| provides a fixed number of 1024 undo slots in its rollback segment, leaving room for 1024 transactions to run in parallel. If all the slots are used any new transaction will fail until a slot is freed, which can cause strange behaviors. This change provides a variable to expand the number of undo slots, up to 4072.
88
9This option is provided for servers that run out of undo slots. Use it if you find the following warning in the error log: ``Warning: cannot find a free slot for an undo log``.9This option is provided for servers that run out of undo slots. Use it if you find the following warning in the error log: ``Warning: cannot find a free slot for an undo log``.
1010
1111
=== modified file 'doc/source/scalability/innodb_io.rst'
--- doc/source/scalability/innodb_io.rst 2012-03-09 08:03:43 +0000
+++ doc/source/scalability/innodb_io.rst 2012-04-02 07:10:25 +0000
@@ -188,6 +188,21 @@
188188
189This variable changes the size of transaction log records. The default size of 512 bytes is good in most situations. However, setting it to 4096 may be a good optimization with SSD cards. While settings other than 512 and 4096 are possible, as a practical matter these are really the only two that it makes sense to use.189This variable changes the size of transaction log records. The default size of 512 bytes is good in most situations. However, setting it to 4096 may be a good optimization with SSD cards. While settings other than 512 and 4096 are possible, as a practical matter these are really the only two that it makes sense to use.
190190
191.. variable:: innodb_log_file_size
192
193 :version 1.0.6-10: Introduced
194 :cli: Yes
195 :conf: Yes
196 :scope: Global
197 :dyn: No
198 :type: Numeric
199 :default: 5242880
200 :range: 1048576 .. 4294967295
201
202In upstream |MySQL| the limit for the combined size of log files must be less than 4GB. But in Percona Server it is:
203 * on 32-bit systems: individual log file limit is 4 GB and total log file size limit is 4 GB, i.e. the same as in the upstream server.
204 * on 64-bit systems: both individual log files and total log file size are practically unlimited (the limit is 2^63 - 1 bytes which is 8+ million TB).
205
191.. variable:: innodb_read_ahead206.. variable:: innodb_read_ahead
192207
193 :cli: Yes208 :cli: Yes

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