MySQL Optimization, Query Monitoring, and Tuning
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MySQL Optimizations Query Monitoring and Tuning

MySQL drives most dynamic web content in the modern age of websites WordPress, Joomla, Drupal and most other application utilize the robust features of MySQL. Your VPS will generally come with a 'vanilla' or default install of MySQL and each site and VPS server should tune or optimize the MySQL server to their needs.

Their are many tools available either through scripts or your package manager (yum or apt) that provide MySQL information we will look at a few.

mytop

mytop is mimics the native top application in Linux but is designed for MySQL information open it gives various status pages and updates every few seconds to install the application run your package installer from SSH

Sample output:

MySQL on localhost (5.1.66-0+squeeze1)                 up 27+06:02:27 [19:27:23]

 Queries: 3.0     qps:    0 Slow:     0.0         Se/In/Up/De(%):    5133/00/00/00

 Key Efficiency: 100.0%  Bps in/out:   0.0/  0.0

        Id      User         Host/IP         DB      Time    Cmd Query or State

        --      ----         -------         --      ----    --- --------------

       292      root       localhost                    0  Query show full processlist

The tool will show slow queries, how many quires in real time.

MySQL Tuner

This is a script that was developed in Perl which outputs MySQL configuration information and recommends actions for performance and stability. the script can be located here MySQL Tuner

Sample output

./mysqltune.pl


 >>  MySQLTuner 1.2.0 - Major Hayden <major@mhtx.net>

 >>  Bug reports, feature requests, and downloads at http://mysqltuner.com/

 >>  Run with '--help' for additional options and output filtering

[OK] Logged in using credentials from debian maintenance account.


-------- General Statistics --------------------------------------------------

[--] Skipped version check for MySQLTuner script

[OK] Currently running supported MySQL version 5.1.66-0+squeeze1

[OK] Operating on 64-bit architecture


-------- Storage Engine Statistics -------------------------------------------

[--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster

[--] Data in MyISAM tables: 100M (Tables: 232)

[--] Data in InnoDB tables: 1M (Tables: 52)

[!!] Total fragmented tables: 61


-------- Security Recommendations  -------------------------------------------


-------- Performance Metrics -------------------------------------------------

[--] Up for: 27d 6h 5m 47s (2K q [0.001 qps], 297 conn, TX: 771K, RX: 87M)

[--] Reads / Writes: 21% / 79%

[--] Total buffers: 58.0M global + 2.7M per thread (151 max threads)

[OK] Maximum possible memory usage: 463.8M (15% of installed RAM)

[OK] Slow queries: 0% (0/2K)

[OK] Highest usage of available connections: 0% (1/151)

[OK] Key buffer size / total MyISAM indexes: 16.0M/108.5M

[OK] Key buffer hit rate: 100.0% (26M cached / 25 reads)

[OK] Query cache efficiency: 24.6% (154 cached / 625 selects)

[OK] Query cache prunes per day: 0

[OK] Sorts requiring temporary tables: 0% (0 temp sorts / 4 sorts)

[OK] Temporary tables created on disk: 24% (164 on disk / 679 total)

[OK] Thread cache hit rate: 99% (1 created / 297 connections)

[!!] Table cache hit rate: 1% (64 open / 3K opened)

[OK] Open file limit used: 9% (96/1K)

[OK] Table locks acquired immediately: 100% (1K immediate / 1K locks)

[OK] InnoDB data size / buffer pool: 1.1M/8.0M


-------- Recommendations -----------------------------------------------------

General recommendations:

    Run OPTIMIZE TABLE to defragment tables for better performance

    Enable the slow query log to troubleshoot bad queries

    Increase table_cache gradually to avoid file descriptor limits

Variables to adjust:

    table_cache (> 64)

MySQL Tuning Primer Script

Finally we have MySQL Tuning Primer Script this script takes 'Show status like' and 'Show variable like' and then attempts to provide recommendations to your MySQL Configuration. the script can be downloaded here MySQL Tuning Primer Script to run this tool you would also need bc installed through your package manager eg apt-get install bc 

Sample output

./primer.sh all


        -- MYSQL PERFORMANCE TUNING PRIMER --

             - By: Matthew Montgomery -


MySQL Version 5.1.66-0+squeeze1 x86_64


Uptime = 27 days 6 hrs 24 min 46 sec

Avg. qps = 0

Total Questions = 3008

Threads Connected = 1


Server has been running for over 48hrs.

It should be safe to follow these recommendations


To find out more information on how each of these

runtime variables effects performance visit:

http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html

Visit http://www.mysql.com/products/enterprise/advisors.html

for info about MySQL's Enterprise Monitoring and Advisory Service


SLOW QUERIES

The slow query log is NOT enabled.

Current long_query_time = 10.000000 sec.

You have 0 out of 3029 that take longer than 10.000000 sec. to complete

Your long_query_time seems to be fine


BINARY UPDATE LOG

The binary update log is NOT enabled.

You will not be able to do point in time recovery

See http://dev.mysql.com/doc/refman/5.1/en/point-in-time-recovery.html


WORKER THREADS

Current thread_cache_size = 8

Current threads_cached = 0

Current threads_per_sec = 0

Historic threads_per_sec = 0

Your thread_cache_size is fine


MAX CONNECTIONS

Current max_connections = 151

Current threads_connected = 1

Historic max_used_connections = 1

The number of used connections is 0% of the configured maximum.

You are using less than 10% of your configured max_connections.

Lowering max_connections could help to avoid an over-allocation of memory

See "MEMORY USAGE" section to make sure you are not over-allocating


INNODB STATUS

Current InnoDB index space = 1 M

Current InnoDB data space = 1 M

Current InnoDB buffer pool free = 64 %

Current innodb_buffer_pool_size = 8 M

Depending on how much space your innodb indexes take up it may be safe

to increase this value to up to 2 / 3 of total system memory


MEMORY USAGE

Max Memory Ever Allocated : 44 M

Configured Max Per-thread Buffers : 405 M

Configured Max Global Buffers : 42 M

Configured Max Memory Limit : 447 M

Physical Memory : 3.00 G

Max memory limit seem to be within acceptable norms


KEY BUFFER

Current MyISAM index space = 108 M

Current key_buffer_size = 16 M

Key cache miss rate is 1 : 1053872

Key buffer free ratio = 81 %

Your key_buffer_size seems to be too high.

Perhaps you can use these resources elsewhere


QUERY CACHE

Query cache is enabled

Current query_cache_size = 16 M

Current query_cache_used = 69 K

Current query_cache_limit = 1 M

Current Query cache Memory fill ratio = .42 %

Current query_cache_min_res_unit = 4 K

Your query_cache_size seems to be too high.

Perhaps you can use these resources elsewhere

MySQL won't cache query results that are larger than query_cache_limit in size


SORT OPERATIONS

Current sort_buffer_size = 2 M

Current read_rnd_buffer_size = 256 K

Sort buffer seems to be fine


JOINS

Current join_buffer_size = 132.00 K

You have had 0 queries where a join could not use an index properly

Your joins seem to be using indexes properly


OPEN FILES LIMIT

Current open_files_limit = 1024 files

The open_files_limit should typically be set to at least 2x-3x

that of table_cache if you have heavy MyISAM usage.

Your open_files_limit value seems to be fine


TABLE CACHE

Current table_open_cache = 64 tables

Current table_definition_cache = 256 tables

You have a total of 307 tables

You have 64 open tables.

Current table_cache hit rate is 1%

, while 100% of your table cache is in use

You should probably increase your table_cache

You should probably increase your table_definition_cache value.


TEMP TABLES

Current max_heap_table_size = 16 M

Current tmp_table_size = 16 M

Of 802 temp tables, 25% were created on disk

Perhaps you should increase your tmp_table_size and/or max_heap_table_size

to reduce the number of disk-based temporary tables

Note! BLOB and TEXT columns are not allow in memory tables.

If you are using these columns raising these values might not impact your

ratio of on disk temp tables.


TABLE SCANS

Current read_buffer_size = 128 K

Current table scan ratio = 37 : 1

read_buffer_size seems to be fine


TABLE LOCKING

Current Lock Wait ratio = 0 : 3284

Your table locking seems to be fine

Optimizations

Now you can edit your my.cnf file and add really any value or setting, the thing to keep in mind is to be very careful as some incorrect settings can cause more problems than solutions.


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