MySQL optimisation Percona LeMug.fr
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★ InnoDB?★ MyISAM?★ XtraDB?★ MySQL 4.x?★ MySQL 5.0.x?★ MySQL 5.1?★ MySQL 5.5?★ Something else?
2
Show of Hands
Tuesday, March 8, 2011
About this presentation
★ Q: “Would you like to talk about MySQL optimization?”★ A: Sure.
★ Optimization can be made at many levels.★ I’m going to show 2-3 parts of the puzzle:
✦ Query Optimization.✦ How InnoDB works.✦ (Time Permitting) Our work at Percona on improving MySQL.
3Tuesday, March 8, 2011
It all starts with EXPLAIN
★ Bookmark this manual page:http://dev.mysql.com/doc/refman/5.1/en/using-explain.html
★ It is the best source for anyone getting started.
4Tuesday, March 8, 2011
Examples come from:
★ IMDB database loaded into InnoDB tables (~5G).
★ Download it and import it for yourself using imdbpy2sql.py:http://imdbpy.sourceforge.net/
5Tuesday, March 8, 2011
First Example
6Tuesday, March 8, 2011
Find the Title Bambi
7
ALL means tablescan
In this case a sort is required because of the order by
Anticipated number of rows to be examined
Additional filtering may be possible before passing to sort.
3.09s
Tuesday, March 8, 2011
Aha! Now add an index:
8Tuesday, March 8, 2011
We must revisit...
9
Using = for comparison, but not primary key lookup.
Size of the index used (in bytes)
Anticipated number of rows to be examined dropped considerably.
Identified title as a candidate index, chose to use it.
0.00s
Tuesday, March 8, 2011
Other ways of accessing
10
Better type of ‘const’. We can stop when we find one row.
0.00s
At most one matching row.
In InnoDB the primary key is often much faster than all other keys.
Tuesday, March 8, 2011
And..
11
Ignore the time with EXPLAIN. Only look at the time for a query.
Type is range. BETWEEN, IN() and < > are also ranges.
Number of rows to be examined has increased - we are not specific enough.
0.00s
Tuesday, March 8, 2011
Why’s that a range?
★ We're looking for titles between BambA and BambZ*★ When we say index in MySQL, we mean trees.
✦ That is, B-Tree/B+Tree/T-Tree.✦ Pretend they're all the same (for simplification).✦ There's no radically different indexing methods in MySQL
unless you play storage engine Bingo**.
12* In reality the range is a little wider** The memory storage engine supports hash indexes
Tuesday, March 8, 2011
What’s that?
13Tuesday, March 8, 2011
Could this be a range?
14
3.2s
Tuesday, March 8, 2011
No, we can’t traverse.
15
Do we head left or right here?
Tuesday, March 8, 2011
LIKE ‘Z%’
16
0.05s
Tuesday, March 8, 2011
LIKE ‘T%’
17
3.13s
Tuesday, March 8, 2011
LIKE ‘The %’
18
3.07s
Tuesday, March 8, 2011
MySQL is (reasonably) smart.
★ It dynamically samples the data to choose which is the better choice - or in some cases uses static statistics*.
★ This helps the optimizer choose:✦ Which indexes will be useful.✦ Which indexes should be avoided.✦ Which is the better index when there is more than one.
19 * To refresh statistics run ANALYZE TABLE table_name;Tuesday, March 8, 2011
Why avoid indexes?
★ B-Trees work like humans search a phone book;✦ Use an index if you want just a few rows.✦ Scan cover-to-cover if you want a large percentage.
20Tuesday, March 8, 2011
★ We benchmarked this on a different schema:
Why avoid indexes (cont.)
21
Table scan has a relatively fixed cost (red line).
The index has completely different effectiveness depending on how much it can filter.
Hopefully MySQL switches at the right point.
Tuesday, March 8, 2011
What you should take away:
★ Data is absolutely critical.✦ Development environments should contain sample data
exported from production systems.★ Input values are absolutely critical.
✦ Between two seemingly identical queries, execution plans may be very different.
22See also: http://www.mysqlperformanceblog.com/2009/10/16/how-not-to-find-unused-indexes/
Tuesday, March 8, 2011
Improve this Query
23
3.41s
This number of rows is a guess. It keeps changing between examples.
Tuesday, March 8, 2011
We’re Spoiled for Choice.
24Tuesday, March 8, 2011
Index on production_year
25
3.53s
Tuesday, March 8, 2011
Might work if...
26
0.92s
Tuesday, March 8, 2011
Index on title(50)
27
0.02s
Tuesday, March 8, 2011
Comparing the two:
28
★ mysql> EXPLAIN SELECT * from title WHERE title = 'Pilot' AND production_year BETWEEN 2006 and 2009\G
Tuesday, March 8, 2011
Composite Indexes.
★ What is better?✦ INDEX py_t (production_year, title)✦ INDEX t_py (title, production_year)
29Tuesday, March 8, 2011
Index on py_t
30
0.02s
http://www.mysqlperformanceblog.com/2010/01/09/getting-around-optimizer-limitations-with-an-in-list/
Tuesday, March 8, 2011
Index on t_py
31
0.00s
Tuesday, March 8, 2011
Recommendations
★ Index over multiple columns if it can improve filtering. i.e.✦ GOOD: Only some pilots made between 2006-2009.✦ BAD: All pilots made between 2006-2009.
32Tuesday, March 8, 2011
Recommendations (cont.)
★ Don't know what order to specify the columns?✦ RULE: Think how to filter the fastest. Use that order left to
right.✦ EXCEPTION: If there's a range (><, BETWEEN, %). Those
always go to the RIGHT.
33 http://www.mysqlperformanceblog.com/2010/01/09/getting-around-optimizer-limitations-with-an-in-list/
Tuesday, March 8, 2011
How InnoDB Works
Tuesday, March 8, 2011
“Numbers everyone should know”
35
L1 cache reference 0.5 nsBranch mispredict 5 nsL2 cache reference 7 nsMutex lock/unlock 25 nsMain memory reference 100 nsCompress 1K bytes with Zippy 3,000 nsSend 2K bytes over 1 Gbps network 20,000 nsRead 1 MB sequentially from memory 250,000 nsRound trip within same datacenter 500,000 nsDisk seek 10,000,000 nsRead 1 MB sequentially from disk 20,000,000 nsSend packet CA->Netherlands->CA 150,000,000 ns
See: http://www.linux-mag.com/cache/7589/1.html and Google http://www.cs.cornell.edu/projects/ladis2009/talks/dean-keynote-ladis2009.pdf
Tuesday, March 8, 2011
About Disks.
★ 10,000,000 ns = 10ms = 100 operations/second.✦ This is about the average for a 7200RPM drive.
★ The actual time has dramatic variation.✦ The variation is because disks are mechanical. ✦ We can much write faster sequentially than randomly.
36Tuesday, March 8, 2011
[default] Everything is buffered!
★ When you write to a file, here’s what happens in the Operating System:
37
Block 9, 10, 1, 4, 200, 5.
Block 1, 4, 5, 9, 10, 200
What happens to this buffer if we loose power?
Tuesday, March 8, 2011
The OS provides a way!
★ $ man fsync
38
Synopsis#include <unistd.h>int fsync(int fd);int fdatasync(int fd);
Descriptionfsync() transfers ("flushes") all modified in-core data of (i.e., modified buffer cache pages for) the file referred to by the file descriptor fd to the disk device (or other permanent storage device) where that file resides. The call blocks until the device reports that the transfer has completed. It also flushes metadata information associated with the file (see stat(2)).
Hint: MyISAM just writes to the OS buffer and has no durability.
http://thunk.org/tytso/blog/2009/03/15/dont-fear-the-fsync/Tuesday, March 8, 2011
Knowing this:
★ InnoDB wants to try and reduce random IO.★ It can not (safely) rely on the operating system’s write
buffering and be ACID compliant.✦ .. and InnoDB algorithms have to compensate.
39Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (High Level)
Log Files
40
SELECT * FROM CityWHERE CountryCode=ʼAUSʼ
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (cont.)
41
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Why don’t we update?
★ This is an optimization!✦ The log file IO is sequential and much cheaper than live
updates.✦ The IO for the eventual updates to the tablespace can be
optimized as well. ★ Provided that you saved enough to recover, this
shouldn’t matter should it?
42Tuesday, March 8, 2011
More on Logs...
★ Logs are only used during recovery.✦ Not even read when we need to write down
dirty pages!★ To figure out which pages need to be evicted we have two
lists - the flush list and the LRU.★ Log activities are all assigned a LSN (log sequence
number).
43
Log Files
Tuesday, March 8, 2011
Log Files, Checkpoints, etc.
★ Most database systems work this way:✦ In Oracle the transaction logs are called “Redo Logs”.
★ The background process of syncing dirty pages is normally referred to as a “Checkpoint”.
★ InnoDB has fuzzy checkpointing.
44Tuesday, March 8, 2011
Log Writing
★ You can change increase innodb_log_file_size. This will allow InnoDB to “smooth out” background IO for longer.
✦ Tip: Optionally you could change innodb_log_files_in_group as well. Be aware that your effective log file is innodb_log_file_size * innodb_log_files_in_group
45Tuesday, March 8, 2011
Log Writing (cont.)
★ You can also change innodb_flush_log_at_trx_commit to 0 or 2 to reduce the durability requirements of this write.✦ Requires less flushing - particularly helpful on systems
without writeback caches!★ innodb_log_buffer_size may also help buffer
changes for longer before writing to the logs.✦ Very workload dependent - tends to be more helpful for
writing big TEXT/BLOB changes.
46Tuesday, March 8, 2011
In summary
★ On commit, the log has to be flushed to guarantee changes.
✦ Nothing else has to be done.★ What visibility do we have into these operations?★ How do we decide how much background work to do per
second?★ What happens if we fall behind in background work?
47Tuesday, March 8, 2011
Enhancements via Percona
Tuesday, March 8, 2011
Terminology
49
Oracle Product License Percona Equivalent Product
License
MySQL Server GPL Percona Server GPL
The InnoDB Storage Engine (Plugin edition)
GPL The XtraDB Storage Engine
GPL
InnoDB Hot Backup Commercial XtraBackup GPL
(GPL = Completely free for you to use. Support not included.)
Tuesday, March 8, 2011
Performance Improvements
50
Improved Buffer Pool Scalability
Improved IO Path + adaptive checkpointing
Improved Rollback Segment Scalability*Separate purge
thread
Data dictionary memory consumption controls
Increased number of undo slots*
Faster page checksums*
Support for different page sizes*
* Changes on disk format (not backwards compatible)
Insert buffer controls
Completely disable the query cache.
Remove excess fcntl calls
Per session configuration of innodb_flush_log_at_trx_commit
Separate location of double write buffer*
Strip comments before using query cache
Transaction logs larger than 4G supported.
Tuesday, March 8, 2011
Improved Buffer Pool Scalability
★ Additional patches to what is already available in the InnoDB Plugin.✦ Splits the buffer pool mutex into smaller mutexes:
• Flush list mutex• LRU mutex• Free mutex• hash mutex
51Tuesday, March 8, 2011
Data Dictionary control
★ Once an InnoDB table is opened it is never freed from the in-memory data dictionary (which is unlimited in size).
★ XtraDB introduces:✦ --innodb_dict_size_limit - a configuration item in
bytes.✦ innodb_dict_tables - a status variable for number
entries in the cache.
52Tuesday, March 8, 2011
Undo Slots
★ In the built-in InnoDB, the number of undo slots is limited to 1024.✦ This means the number of open transactions is limited to
1023. See: http://bugs.mysql.com/bug.php?id=26590✦ Some statements require 2 undo slots.
★ In XtraDB, this is expanded to 4072 with --innodb_extra_undoslots=1.
53 Warning: This is binary format incompatible!Tuesday, March 8, 2011
Rollback Segments
★ In XtraDB, it’s also possible to have more than one rollback segment.✦ Each segment contains undo slots.
★ Configuration is --innodb-extra-rsegments=N★ This has the added effect of reducing mutex contention
on the rollback segment:✦ “Mutex at 0×1b3e3e78 created file trx/trx0rseg.c line 167″
54
http://www.percona.com/docs/wiki/percona-xtradb:patch:innodb_extra_rseghttp://www.mysqlperformanceblog.com/2009/10/14/tuning-for-heavy-writing-workloads/
Warning: This is binary format incompatible!Tuesday, March 8, 2011
Fast Checksums
★ The InnoDB page checksum computation is slower than it needs to be.
★ XtraDB has the option to use a faster checksum format.
55 Warning: This is binary format incompatible!Tuesday, March 8, 2011
Different Page Sizes
★ XtraDB now has support for different page sizes - 4K, 8K, 16K.
56 Warning: This is binary format incompatible!Tuesday, March 8, 2011
Separate Purge Thread
★ Cleans up a long history list length faster:
57See: http://www.mysqlperformanceblog.com/2009/10/14/tuning-for-heavy-writing-workloads/
Tuesday, March 8, 2011
Usability Enhancements
58
Show contents of the buffer pool
Import / export of innodb_file_per_table tables
Import / export of buffer pool contents
Transactional Replication
Better handling of corrupted tables
Store buffer pool in shared memory segment
Save index statistics between restarts
Advise in processlist when waiting on Query cache mutex.
Improved slow query log
User / Index / Table statistics
Disable automatic statistics regeneration
Show data dictionary
Deadlock counter
Show Temporary Tables
Log connection errors
Retain query response time distribution.
Tuesday, March 8, 2011
Show Buffer Pool Contents
59
mysql> SELECT d.*,round(100*cnt*16384/(data_length+index_length),2) fit FROM (SELECT schema_name,table_name,count(*) cnt,sum(dirty),sum(hashed) FROM INNODB_BUFFER_POOL_PAGES_INDEX GROUP BY schema_name,table_name ORDER BY cnt DESC LIMIT 20) d JOIN TABLES ON (TABLES.table_schema=d.schema_name AND TABLES.table_name=d.table_name);+-------------+---------------------+---------+------------+-------------+--------+| schema_name | table_name | cnt | sum(dirty) | sum(hashed) | fit |+-------------+---------------------+---------+------------+-------------+--------+| db | table1 | 1699133 | 13296 | 385841 | 87.49 || db | table2 | 1173272 | 17399 | 11099 | 98.42 || db | table3 | 916641 | 7849 | 15316 | 94.77 || db | table4 | 86999 | 1555 | 75554 | 87.42 || db | table5 | 32701 | 7997 | 30082 | 91.61 || db | table6 | 31990 | 4495 | 25681 | 102.97 || db | table7 | 1 | 0 | 0 | 100.00 |+-------------+---------------------+---------+------------+-------------+--------+7 rows in set (26.45 sec)
Source: http://www.mysqlperformanceblog.com/2010/03/26/tables-fit-buffer-poo/* Command may differ slightly between versions.
Tuesday, March 8, 2011
Save Buffer Pool Contents
★ Export the contents of the buffer pool to a file called ‘ib_lru_dump’ in the data directory:✦ SELECT * FROM information_schema.XTRADB_ADMIN_COMMAND /*!XTRA_LRU_DUMP*/;
★ Restored ib_lru_dump:✦ SELECT * FROM information_schema.XTRADB_ADMIN_COMMAND /*!XTRA_LRU_RESTORE*/;
60Note: Not the actual contents - it takes 8 bytes to remember the address of a 16K page.
Tuesday, March 8, 2011
Import/Export tables
★ Because --innodb-file-per-table still has information (data dictionary, undo) in the global tablespace you can’t just back it up by itself.
★ With a new setting, --innodb_expand_import=1, this is no longer the case.
★ Tip: The import/export still has to be done with XtraBackup. Documentation available here:http://www.percona.com/docs/wiki/percona-xtradb:patch:innodb_expand_import
61Tuesday, March 8, 2011
The Slow Query Log
62
$ mysql -e “SET GLOBAL log_slow_verbosity = ‘full’;”$ tail /var/log/mysql.slow..# Time: 100924 13:58:47# User@Host: root[root] @ localhost []# Thread_id: 10 Schema: imdb Last_errno: 0 Killed: 0# Query_time: 399.563977 Lock_time: 0.000110 Rows_sent: 1 Rows_examined: 46313608 Rows_affected: 0 Rows_read: 1# Bytes_sent: 131 Tmp_tables: 1 Tmp_disk_tables: 1 Tmp_table_sizes: 25194923# InnoDB_trx_id: 1403# QC_Hit: No Full_scan: Yes Full_join: No Tmp_table: Yes Tmp_table_on_disk: Yes# Filesort: Yes Filesort_on_disk: Yes Merge_passes: 5# InnoDB_IO_r_ops: 1064749 InnoDB_IO_r_bytes: 17444847616 InnoDB_IO_r_wait: 26.935662# InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000# InnoDB_pages_distinct: 65329SET timestamp=1285336727;select STRAIGHT_JOIN count(*) as c, person_id FROM cast_info FORCE INDEX(person_id) INNER JOIN title ON (cast_info.movie_id=title.id) WHERE title.kind_id = 1 GROUP BY cast_info.person_id ORDER by c DESC LIMIT 1;
$ tail /var/log/mysql.slow..# Time: 100924 13:58:47# User@Host: root[root] @ localhost []# Query_time: 399.563977 Lock_time: 0.000110 Rows_sent: 1 Rows_examined: 46313608SET timestamp=1285336727;select STRAIGHT_JOIN count(*) as c, person_id FROM cast_info FORCE INDEX(person_id) INNER JOIN title ON (cast_info.movie_id=title.id) WHERE title.kind_id = 1 GROUP BY cast_info.person_id ORDER by c DESC LIMIT 1;
MySQL Server
Percona Server
Tuesday, March 8, 2011
User Statistics
63
mysql> SET GLOBAL userstat_running = 1;mysql> SELECT DISTINCT s.TABLE_SCHEMA, s.TABLE_NAME, s.INDEX_NAME FROM information_schema.statistics `s` LEFT JOIN information_schema.index_statistics IS ON (s.TABLE_SCHEMA = IS.TABLE_SCHEMA AND s.TABLE_NAME=IS.TABLE_NAME AND s.INDEX_NAME=IS.INDEX_NAME) WHERE IS.TABLE_SCHEMA IS NULL;+--------------+---------------------------+-----------------+| TABLE_SCHEMA | TABLE_NAME | INDEX_NAME |+--------------+---------------------------+-----------------+| art100 | article100 | ext_key | | art100 | article100 | site_id | | art100 | article100 | hash | | art100 | article100 | forum_id_2 | | art100 | article100 | published | | art100 | article100 | inserted | | art100 | article100 | site_id_2 | | art100 | author100 | PRIMARY | | art100 | author100 | site_id | ...+--------------+---------------------------+-----------------+1150 rows IN SET (1 min 44.23 sec)
MySQL Server
Percona Server
( Not Possible )
Tuesday, March 8, 2011
(Related) Xtrabackup Features
★ Report on fragmentation of indexes:★ $ xtrabackup --stats --tables=art.link* --datadir=/mnt/data/mysql/...table: art/link_out104, index: PRIMARY, space id: 12, root page 3leaf pages: recs=25958413, pages=497839, data=7492026403 bytes, data/pages=91%...
64
http://www.mysqlperformanceblog.com/2009/09/14/statistics-of-innodb-tables-and-indexes-available-in-xtrabackup/
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
Increase the size of the log files (innodb_log_file_size and innodb_log_files_in_group)
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
Set innodb_flush_log_at_trx_commit=2 if durability is not as important.
Increase the size of the log files (innodb_log_file_size and innodb_log_files_in_group)
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
Typically use innodb_flush_method=O_DIRECT if using a Hardware RAID controller.
Set innodb_flush_log_at_trx_commit=2 if durability is not as important.
Increase the size of the log files (innodb_log_file_size and innodb_log_files_in_group)
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
(Possibly) Move the log files to separate spindles (sequential IO)
Typically use innodb_flush_method=O_DIRECT if using a Hardware RAID controller.
Set innodb_flush_log_at_trx_commit=2 if durability is not as important.
Increase the size of the log files (innodb_log_file_size and innodb_log_files_in_group)
Tuesday, March 8, 2011
Basic Operation (again.)
65
Log Files
UPDATE City SET name = 'Morgansville'
WHERE name = 'Brisbane' AND CountryCode='AUS'
01010
Buffer PoolTablespace
Set innodb_buffer_pool_size to “50-80%” of memory.
(Possibly) Move the log files to separate spindles (sequential IO)
Typically use innodb_flush_method=O_DIRECT if using a Hardware RAID controller.
Set innodb_flush_log_at_trx_commit=2 if durability is not as important.
If innodb_log_waits > 0 the buffer being filled (innodb_log_buffer_size) before writing to the log files may be too small.
Increase the size of the log files (innodb_log_file_size and innodb_log_files_in_group)
Tuesday, March 8, 2011
The End.
★ Questions?
66Tuesday, March 8, 2011