1 # phpMyAdmin Advisory rules file
2 # Use only UNIX style newlines
3 # This file is being parsed by Advisor.class.php, which should handle syntax errors correctly.
4 # However, PHP Warnings and the like are being consumed by the phpMyAdmin error handler, so those won't show up
5 # E.g.: Justification line is empty because you used an unescape percent sign, sprintf() returns an empty string and no warning/error is shown
8 # 'rule' identifier[the name of the rule] eexpr [an optional precondition]
9 # expr [variable or value calculation used for the test]
10 # expr [test, if evaluted to 'true' it fires the rule. Use 'value' to insert the calculated value (without quotes)]
11 # string [the issue (what is the problem?)]
12 # string [the recommendation (how do i fix it?)]
13 # formatted-string '|' comma-seperated-expr [the justification (result of the calculated value / why did this rule fire?)]
15 # comma-seperated-expr: expr(,expr)*
16 # eexpr: [expr] - expr enclosed in []
17 # expr: a php code literal with extras:
18 # - variable names are replaced with their respective values
19 # - fired('name of rule') is replaced with true/false when given rule has been fired. Note however that this is a very simple rules engine. Rules are only checked in sequential order as they are written down here. If given rule has not been checked yet, fired() will always evaluate to false
20 # - 'value' is replaced with the calculated value. If it is a string, it will be put within single quotes
21 # - other than that you may use any php function, initialized variable or constant
23 # identifier: A string enclosed in single quotes
24 # string: A quoteless string, may contain HTML. Variable names enclosed in curly braces are replaced with links to directly edit this variable. e.g. {tmp_table_size}
25 # formatted-string: You may use classic php sprintf() string formatting here, the arguments must be appended after a trailing pipe (|) as mentioned in above syntax
26 # percent signs (%) are automatically escaped (%%) in the following cases: When followed by a space, dot or comma and at the end of the line)
28 # Comments start with #
33 rule 'Uptime below one day'
36 Uptime is less than 1 day, performance tuning may not be accurate.
37 To have more accurate averages it is recommended to let the server run for longer than a day before running this analyzer
38 The uptime is only %s | PMA_timespanFormat(Uptime)
40 rule 'Questions below 1,000'
43 Fewer than 1,000 questions have been run against this server. The recommendations may not be accurate.
44 Let the server run for a longer time until it has executed a greater amount of queries.
45 Current amount of Questions: %s | Questions
47 rule 'Percentage of slow queries' [Questions > 0 && !PMA_DRIZZLE]
48 Slow_queries / Questions * 100
50 There is a lot of slow queries compared to the overall amount of Queries.
51 You might want to increase {long_query_time} or optimize the queries listed in the slow query log
52 The slow query rate should be below 5%, your value is %s%. | round(value,2)
54 rule 'Slow query rate' [Questions > 0]
55 (Slow_queries / Questions * 100) / Uptime
57 There is a high percentage of slow queries compared to the server uptime.
58 You might want to increase {long_query_time} or optimize the queries listed in the slow query log
59 You have a slow query rate of %s per hour, you should have less than 1% per hour. | PMA_bytime(value,2)
61 rule 'Long query time' [!PMA_DRIZZLE]
64 long_query_time is set to 10 seconds or more, thus only slow queries that take above 10 seconds are logged.
65 It is suggested to set {long_query_time} to a lower value, depending on your environment. Usually a value of 1-5 seconds is suggested.
66 long_query_time is currently set to %ds. | value
68 rule 'Slow query logging' [!PMA_DRIZZLE]
71 The slow query log is disabled.
72 Enable slow query logging by setting {log_slow_queries} to 'ON'. This will help troubleshooting badly performing queries.
73 log_slow_queries is set to 'OFF'
77 rule 'Release Series' [!PMA_DRIZZLE]
79 substr(value,0,1) <= 5 && substr(value,2,1) < 1
80 The MySQL server version less then 5.1.
81 You should upgrade, as MySQL 5.1 has improved performance, and MySQL 5.5 even more so.
82 Current version: %s | value
84 rule 'Minor Version' [! fired('Release Series')]
86 substr(value,0,1) <= 5 && substr(value,2,1) < 1 && substr(value,4,2) < 30
87 Version less than 5.1.30 (the first GA release of 5.1).
88 You should upgrade, as recent versions of MySQL 5.1 have improved performance and MySQL 5.5 even more so.
89 Current version: %s | value
91 rule 'Minor Version' [! fired('Release Series')]
93 substr(value,0,1) == 5 && substr(value,2,1) == 5 && substr(value,4,2) < 8
94 Version less than 5.5.8 (the first GA release of 5.5).
95 You should upgrade, to a stable version of MySQL 5.5
96 Current version: %s | value
100 preg_match('/source/i',value)
101 Version is compiled from source, not a MySQL official binary.
102 If you did not compile from source, you may be using a package modified by a distribution. The MySQL manual only is accurate for official MySQL binaries, not any package distributions (such as RedHat, Debian/Ubuntu etc).
103 'source' found in version_comment
107 preg_match('/percona/i',value)
108 The MySQL manual only is accurate for official MySQL binaries.
109 Percona documentation is at http://www.percona.com/docs/wiki/
110 'percona' found in version_comment
115 The MySQL manual only is accurate for official MySQL binaries.
116 Drizzle documentation is at http://docs.drizzle.org/
117 Version string (%s) matches Drizzle versioning scheme | value
119 rule 'MySQL Architecture'
121 value > 3072*1024 && !preg_match('/64/',version_compile_machine) && !preg_match('/64/',version_compile_os)
122 MySQL is not compiled as a 64-bit package.
123 Your memory capacity is above 3 GiB (assuming the Server is on localhost), so MySQL might not be able to access all of your memory. You might want to consider installing the 64-bit version of MySQL.
124 Available memory on this host: %s | implode(' ',PMA_formatByteDown(value*1024, 2, 2))
129 # Lame: 'ON' == 0 is true, so you need to compare 'ON' == '0'
130 rule 'Query cache disabled' [!PMA_DRIZZLE]
132 value == 0 || query_cache_type == 'OFF' || query_cache_type == '0'
133 The query cache is not enabled.
134 The query cache is known to greatly improve performance if configured correctly. Enable it by setting {query_cache_size} to a 2 digit MiB value and setting {query_cache_type} to 'ON'. <b>Note:</b> If you are using memcached, ignore this recommendation.
135 query_cache_size is set to 0 or query_cache_type is set to 'OFF'
137 rule 'Query caching method' [!fired('Query cache disabled')]
140 Suboptimal caching method.
141 You are using the MySQL Query cache with a fairly high traffic database. It might be worth considering to use <a href="http://dev.mysql.com/doc/refman/5.5/en/ha-memcached.html">memcached</a> instead of the MySQL Query cache, especially if you have multiple slaves.
142 The query cache is enabled and the server receives %d queries per second. This rule fires if there is more than 100 queries per second. | round(value,1)
144 rule 'Query cache efficiency (%)' [!PMA_DRIZZLE && Com_select + Qcache_hits > 0 && !fired('Query cache disabled')]
145 Qcache_hits / (Com_select + Qcache_hits) * 100
147 Query cache not running efficiently, it has a low hit rate.
148 Consider increasing {query_cache_limit}.
149 The current query cache hit rate of %s% is below 20% | round(value,1)
151 rule 'Query Cache usage' [!fired('Query cache disabled') && !PMA_DRIZZLE]
152 100 - Qcache_free_memory / query_cache_size * 100
154 Less than 80% of the query cache is being utilized.
155 This might be caused by {query_cache_limit} being too low. Flushing the query cache might help as well.
156 The current ratio of free query cache memory to total query cache size is %s%. It should be above 80% | round(value,1)
158 rule 'Query cache fragmentation' [!fired('Query cache disabled') && !PMA_DRIZZLE]
159 Qcache_free_blocks / (Qcache_total_blocks / 2) * 100
161 The query cache is considerably fragmented.
162 Severe fragmentation is likely to (further) increase Qcache_lowmem_prunes. This might be caused by many Query cache low memory prunes due to {query_cache_size} being too small. For a immediate but short lived fix you can flush the query cache (might lock the query cache for a long time). Carefully adjusting {query_cache_min_res_unit} to a lower value might help too, e.g. you can set it to the average size of your queries in the cache using this formula: (query_cache_size - qcache_free_memory) / qcache_queries_in_cache
163 The cache is currently fragmented by %s% , with 100% fragmentation meaning that the query cache is an alternating pattern of free and used blocks. This value should be below 20%. | round(value,1)
165 rule 'Query cache low memory prunes' [!PMA_DRIZZLE && Qcache_inserts > 0 && !fired('Query cache disabled')]
166 Qcache_lowmem_prunes / Qcache_inserts * 100
168 Cached queries are removed due to low query cache memory from the query cache.
169 You might want to increase {query_cache_size}, however keep in mind that the overhead of maintaining the cache is likely to increase with its size, so do this in small increments and monitor the results.
170 The ratio of removed queries to inserted queries is %s%. The lower this value is, the better (This rules firing limit: 0.1%) | round(value,1)
172 rule 'Query cache max size' [!fired('Query cache disabled')]
175 The query cache size is above 128 MiB. Big query caches may cause significant overhead that is required to maintain the cache.
176 Depending on your environment, it might be performance increasing to reduce this value.
177 Current query cache size: %s | implode(' ',PMA_formatByteDown(value, 2, 2))
179 rule 'Query cache min result size' [!fired('Query cache disabled')]
182 The max size of the result set in the query cache is the default of 1 MiB.
183 Changing {query_cache_limit} (usually by increasing) may increase efficiency. This variable determines the maximum size a query result may have to be inserted into the query cache. If there are many query results above 1 MiB that are well cacheable (many reads, little writes) then increasing {query_cache_limit} will increase efficiency. Whereas in the case of many query results being above 1 MiB that are not very well cacheable (often invalidated due to table updates) increasing {query_cache_limit} might reduce efficiency.
184 query_cache_limit is set to 1 MiB
188 rule 'Percentage of sorts that cause temporary tables' [Sort_scan + Sort_range > 0]
189 Sort_merge_passes / (Sort_scan + Sort_range) * 100
191 Too many sorts are causing temporary tables.
192 Consider increasing sort_buffer_size and/or read_rnd_buffer_size, depending on your system memory limits
193 %s% of all sorts cause temporary tables, this value should be lower than 10%. | round(value,1)
195 rule 'Rate of sorts that cause temporary tables'
196 Sort_merge_passes / Uptime
198 Too many sorts are causing temporary tables.
199 Consider increasing sort_buffer_size and/or read_rnd_buffer_size, depending on your system memory limits
200 Temporary tables average: %s, this value should be less than 1 per hour. | PMA_bytime(value,2)
205 There are lots of rows being sorted.
206 While there is nothing wrong with a high amount of row sorting, you might want to make sure that the queries which require a lot of sorting use indexed columns in the ORDER BY clause, as this will result in much faster sorting
207 Sorted rows average: %s | PMA_bytime(value,2)
210 rule 'Rate of joins without indexes'
211 (Select_range_check + Select_scan + Select_full_join) / Uptime
213 There are too many joins without indexes.
214 This means that joins are doing full table scans. Adding indexes for the columns being used in the join conditions will greatly speed up table joins
215 Table joins average: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
217 rule 'Rate of reading first index entry'
218 Handler_read_first / Uptime
220 The rate of reading the first index entry is high.
221 This usually indicates frequent full index scans. Full index scans are faster than table scans but require lots of CPU cycles in big tables, if those tables that have or had high volumes of UPDATEs and DELETEs, running 'OPTIMIZE TABLE' might reduce the amount of and/or speed up full index scans. Other than that full index scans can only be reduced by rewriting queries.
222 Index scans average: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
224 rule 'Rate of reading fixed position'
225 Handler_read_rnd / Uptime
227 The rate of reading data from a fixed position is high.
228 This indicates that many queries need to sort results and/or do a full table scan, including join queries that do not use indexes. Add indexes where applicable.
229 Rate of reading fixed position average: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
231 rule 'Rate of reading next table row'
232 Handler_read_rnd_next / Uptime
234 The rate of reading the next table row is high.
235 This indicates that many queries are doing full table scans. Add indexes where applicable.
236 Rate of reading next table row: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
239 rule 'tmp_table_size vs. max_heap_table_size'
240 tmp_table_size - max_heap_table_size
242 tmp_table_size and max_heap_table_size are not the same.
243 If you have deliberately changed one of either: The server uses the lower value of either to determine the maximum size of in-memory tables. So if you wish to increase the in-memory table limit you will have to increase the other value as well.
244 Current values are tmp_table_size: %s, max_heap_table_size: %s | implode(' ',PMA_formatByteDown(tmp_table_size, 2, 2)), implode(' ',PMA_formatByteDown(max_heap_table_size, 2, 2))
246 rule 'Percentage of temp tables on disk' [Created_tmp_tables + Created_tmp_disk_tables > 0]
247 Created_tmp_disk_tables / (Created_tmp_tables + Created_tmp_disk_tables) * 100
249 Many temporary tables are being written to disk instead of being kept in memory.
250 Increasing {max_heap_table_size} and {tmp_table_size} might help. However some temporary tables are always being written to disk, independent of the value of these variables. To eliminate these you will have to rewrite your queries to avoid those conditions (Within a temporary table: Presence of a BLOB or TEXT column or presence of a column bigger than 512 bytes) as mentioned in the beginning of an <a href="http://www.facebook.com/note.php?note_id=10150111255065841&comments">Article by the Pythian Group</a>
251 %s% of all temporary tables are being written to disk, this value should be below 25% | round(value,1)
253 rule 'Temp disk rate'
254 Created_tmp_disk_tables / Uptime
256 Many temporary tables are being written to disk instead of being kept in memory.
257 Increasing {max_heap_table_size} and {tmp_table_size} might help. However some temporary tables are always being written to disk, independent of the value of these variables. To eliminate these you will have to rewrite your queries to avoid those conditions (Within a temporary table: Presence of a BLOB or TEXT column or presence of a column bigger than 512 bytes) as mentioned in the <a href="http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html">MySQL Documentation</a>
258 Rate of temporary tables being written to disk: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
260 # I couldn't find any source on the internet that suggests a direct relation between high counts of temporary tables and any of these variables.
261 # Several independent Blog entries suggest (http://ronaldbradford.com/blog/more-on-understanding-sort_buffer_size-2010-05-10/ and http://www.xaprb.com/blog/2010/05/09/how-to-tune-mysqls-sort_buffer_size/)
262 # that sort_buffer_size should be left as it is. And increasing read_buffer_size is only suggested when there are a lot of
263 # table scans (http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html#sysvar_read_buffer_size and other sources) though
264 # setting it too high is bad too (http://www.mysqlperformanceblog.com/2007/09/17/mysql-what-read_buffer_size-value-is-optimal/).
265 #rule 'Temp table rate'
266 # Created_tmp_tables / Uptime
267 # value * 60 * 60 > 1
268 # Many intermediate temporary tables are being created.
269 # This may be caused by queries under certain conditions as mentioned in the <a href="http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html">MySQL Documentation</a>. Consider increasing {sort_buffer_size} (sorting), {read_rnd_buffer_size} (random read buffer, ie, post-sort), {read_buffer_size} (sequential scan).
273 rule 'MyISAM key buffer size' [!PMA_DRIZZLE]
276 Key buffer is not initialized. No MyISAM indexes will be cached.
277 Set {key_buffer_size} depending on the size of your MyISAM indexes. 64M is a good start.
280 rule 'Max % MyISAM key buffer ever used' [!PMA_DRIZZLE && key_buffer_size > 0]
281 Key_blocks_used * key_cache_block_size / key_buffer_size * 100
283 MyISAM key buffer (index cache) % used is low.
284 You may need to decrease the size of {key_buffer_size}, re-examine your tables to see if indexes have been removed, or examine queries and expectations about what indexes are being used.
285 max % MyISAM key buffer ever used: %s, this value should be above 95% | round(value,1)
287 # Don't fire if above rule fired - we don't need the same advice twice
288 rule 'Percentage of MyISAM key buffer used' [!PMA_DRIZZLE && key_buffer_size > 0 && !fired('max % MyISAM key buffer ever used')]
289 ( 1 - Key_blocks_unused * key_cache_block_size / key_buffer_size) * 100
291 MyISAM key buffer (index cache) % used is low.
292 You may need to decrease the size of {key_buffer_size}, re-examine your tables to see if indexes have been removed, or examine queries and expectations about what indexes are being used.
293 % MyISAM key buffer used: %s, this value should be above 95% | round(value,1)
295 rule 'Percentage of index reads from memory' [!PMA_DRIZZLE && Key_read_requests > 0]
296 100 - (Key_reads / Key_read_requests * 100)
298 The % of indexes that use the MyISAM key buffer is low.
299 You may need to increase {key_buffer_size}.
300 Index reads from memory: %s%, this value should be above 95% | round(value,1)
304 rule 'Rate of table open' [!PMA_DRIZZLE]
305 Opened_tables / Uptime
307 The rate of opening tables is high.
308 Opening tables requires disk I/O which is costly. Increasing {table_open_cache} might avoid this.
309 Opened table rate: %s, this value should be less than 10 per hour | PMA_bytime(value,2)
311 rule 'Percentage of used open files limit' [!PMA_DRIZZLE]
312 Open_files / open_files_limit * 100
314 The number of open files is approaching the max number of open files. You may get a "Too many open files" error.
315 Consider increasing {open_files_limit}, and check the error log when restarting after changing open_files_limit.
316 The number of opened files is at %s% of the limit. It should be below 85% | round(value,1)
318 rule 'Rate of open files' [!PMA_DRIZZLE]
321 The rate of opening files is high.
322 Consider increasing {open_files_limit}, and check the error log when restarting after changing open_files_limit.
323 Opened files rate: %s, this value should be less than 5 per hour | PMA_bytime(value,2)
325 rule 'Immediate table locks %' [Table_locks_waited + Table_locks_immediate > 0]
326 Table_locks_immediate / (Table_locks_waited + Table_locks_immediate) * 100
328 Too many table locks were not granted immediately.
329 Optimize queries and/or use InnoDB to reduce lock wait.
330 Immediate table locks: %s%, this value should be above 95% | round(value,1)
332 rule 'Table lock wait rate'
333 Table_locks_waited / Uptime
335 Too many table locks were not granted immediately.
336 Optimize queries and/or use InnoDB to reduce lock wait.
337 Table lock wait rate: %s, this value should be less than 1 per hour | PMA_bytime(value,2)
339 rule 'Thread cache' [!PMA_DRIZZLE]
342 Thread cache is disabled, resulting in more overhead from new connections to MySQL.
343 Enable the thread cache by setting {thread_cache_size} > 0.
344 The thread cache is set to 0
346 rule 'Thread cache hit rate %' [!PMA_DRIZZLE && thread_cache_size > 0]
347 100 - Threads_created / Connections
349 Thread cache is not efficient.
350 Increase {thread_cache_size}.
351 Thread cache hitrate: %s%, this value should be above 80% | round(value,1)
353 rule 'Threads that are slow to launch' [!PMA_DRIZZLE && slow_launch_time > 0]
356 There are too many threads that are slow to launch.
357 This generally happens in case of general system overload as it is pretty simple operations. You might want to monitor your system load carefully.
358 %s thread(s) took longer than %s seconds to start, it should be 0 | value, slow_launch_time
360 rule 'Slow launch time' [!PMA_DRIZZLE]
363 Slow_launch_threads is above 2s
364 Set slow_launch_time to 1s or 2s to correctly count threads that are slow to launch
365 slow_launch_time is set to %s | value
369 rule 'Percentage of used connections' [!PMA_DRIZZLE]
370 Max_used_connections / max_connections * 100
372 The maximum amount of used connections is getting close to the value of max_connections.
373 Increase max_connections, or decrease wait_timeout so that connections that do not close database handlers properly get killed sooner. Make sure the code closes database handlers properly.
374 Max_used_connections is at %s% of max_connections, it should be below 80% | round(value,1)
376 rule 'Percentage of aborted connections'
377 Aborted_connects / Connections * 100
379 Too many connections are aborted.
380 Connections are usually aborted when they cannot be authorized. <a href="http://www.mysqlperformanceblog.com/2008/08/23/how-to-track-down-the-source-of-aborted_connects/">This article</a> might help you track down the source.
381 %s% of all connections are aborted. This value should be below 1% | round(value,1)
383 rule 'Rate of aborted connections'
384 Aborted_connects / Uptime
386 Too many connections are aborted.
387 Connections are usually aborted when they cannot be authorized. <a href="http://www.mysqlperformanceblog.com/2008/08/23/how-to-track-down-the-source-of-aborted_connects/">This article</a> might help you track down the source.
388 Aborted connections rate is at %s, this value should be less than 1 per hour | PMA_bytime(value,2)
390 rule 'Percentage of aborted clients'
391 Aborted_clients / Connections * 100
393 Too many clients are aborted.
394 Clients are usually aborted when they did not close their connection to MySQL properly. This can be due to network issues or code not closing a database handler properly. Check your network and code.
395 %s% of all clients are aborted. This value should be below 2% | round(value,1)
397 rule 'Rate of aborted clients'
398 Aborted_clients / Uptime
400 Too many clients are aborted.
401 Clients are usually aborted when they did not close their connection to MySQL properly. This can be due to network issues or code not closing a database handler properly. Check your network and code.
402 Aborted client rate is at %s, this value should be less than 1 per hour | PMA_bytime(value,2)
406 rule 'Is InnoDB disabled?' [!PMA_DRIZZLE]
409 You do not have InnoDB enabled.
410 InnoDB is usually the better choice for table engines.
411 have_innodb is set to 'value'
413 rule 'InnoDB log size' [innodb_buffer_pool_size > 0]
414 innodb_log_file_size / innodb_buffer_pool_size * 100
416 The InnoDB log file size is not an appropriate size, in relation to the InnoDB buffer pool.
417 Especially on a system with a lot of writes to InnoDB tables you should set innodb_log_file_size to 25% of {innodb_buffer_pool_size}. However the bigger this value, the longer the recovery time will be when database crashes, so this value should not be set much higher than 256 MiB. Please note however that you cannot simply change the value of this variable. You need to shutdown the server, remove the InnoDB log files, set the new value in my.cnf, start the server, then check the error logs if everything went fine. See also <a href="http://mysqldatabaseadministration.blogspot.com/2007/01/increase-innodblogfilesize-proper-way.html">this blog entry</a>
418 Your InnoDB log size is at %s% in relation to the InnoDB buffer pool size, it should not be below 20% | round(value,1)
420 rule 'Max InnoDB log size' [innodb_buffer_pool_size > 0 && innodb_log_file_size / innodb_buffer_pool_size * 100 < 30]
421 innodb_log_file_size / (1024 * 1024)
423 The InnoDB log file size is inadequately large.
424 It is usually sufficient to set innodb_log_file_size to 25% of the size of {innodb_buffer_pool_size}. A very big innodb_log_file_size slows down the recovery time after a database crash considerably. See also <a href="http://www.mysqlperformanceblog.com/2006/07/03/choosing-proper-innodb_log_file_size/">this Article</a>. You need to shutdown the server, remove the InnoDB log files, set the new value in my.cnf, start the server, then check the error logs if everything went fine. See also <a href="http://mysqldatabaseadministration.blogspot.com/2007/01/increase-innodblogfilesize-proper-way.html">this blog entry</a>
425 Your absolute InnoDB log size is %s MiB | round(value,1)
427 rule 'InnoDB buffer pool size' [system_memory > 0]
428 innodb_buffer_pool_size / system_memory * 100
430 Your InnoDB buffer pool is fairly small.
431 The InnoDB buffer pool has a profound impact on performance for InnoDB tables. Assign all your remaining memory to this buffer. For database servers that use solely InnoDB as storage engine and have no other services (e.g. a web server) running, you may set this as high as 80% of your available memory. If that is not the case, you need to carefully assess the memory consumption of your other services and non-InnoDB-Tables and set this variable accordingly. If it is set too high, your system will start swapping, which decreases performance significantly. See also <a href="http://www.mysqlperformanceblog.com/2007/11/03/choosing-innodb_buffer_pool_size/">this article</a>
432 You are currently using %s% of your memory for the InnoDB buffer pool. This rule fires if you are assigning less than 60%, however this might be perfectly adequate for your system if you don't have much InnoDB tables or other services running on the same machine. | value
436 rule 'MyISAM concurrent inserts' [!PMA_DRIZZLE]
438 value === 0 || value === 'NEVER'
439 Enable concurrent_insert by setting it to 1
440 Setting {concurrent_insert} to 1 reduces contention between readers and writers for a given table. See also <a href="http://dev.mysql.com/doc/refman/5.5/en/concurrent-inserts.html">MySQL Documentation</a>
441 concurrent_insert is set to 0
443 # INSERT DELAYED USAGE
445 #Delayed_insert_threads 0
447 #Not_flushed_delayed_rows