Mysql：命令选项、配置选项、（全局、会话）系统变量、状态变量：状态变量

Server Status Variables

The server maintains many status variables that provide information about its operation. You can view these variables and their values by using the SHOW [GLOBAL | SESSION] STATUS statement (see Section 12.5.5.37, “SHOW STATUS Syntax”). The optional GLOBAL keyword aggregates the values over all connections, and SESSION shows the values for the current connection.

mysql> SHOW GLOBAL STATUS;
+-----------------------------------+------------+
| Variable_name                     | Value      |
+-----------------------------------+------------+
| Aborted_clients                   | 0          |
| Aborted_connects                  | 0          |
| Bytes_received                    | 155372598  |
| Bytes_sent                        | 1176560426 |
...
| Connections                       | 30023      |
| Created_tmp_disk_tables           | 0          |
| Created_tmp_files                 | 3          |
| Created_tmp_tables                | 2          |
...
| Threads_created                   | 217        |
| Threads_running                   | 88         |
| Uptime                            | 1389872    |
+-----------------------------------+------------+

The following table lists all available server status variables:

Variable Name	Variable Type	Variable Scope
Aborted_clients	numeric	GLOBAL
Aborted_connects	numeric	GLOBAL
Binlog_cache_disk_use	numeric	GLOBAL
Binlog_cache_use	numeric	GLOBAL
Bytes_received	numeric	GLOBAL | SESSION
Bytes_sent	numeric	GLOBAL | SESSION
Com_admin_commands	numeric	GLOBAL | SESSION
Com_alter_db	numeric	GLOBAL | SESSION
Com_alter_event	numeric	GLOBAL | SESSION
Com_alter_table	numeric	GLOBAL | SESSION
Com_analyze	numeric	GLOBAL | SESSION
Com_backup_table	numeric	GLOBAL | SESSION
Com_begin	numeric	GLOBAL | SESSION
Com_call_procedure	numeric	GLOBAL | SESSION
Com_change_db	numeric	GLOBAL | SESSION
Com_change_master	numeric	GLOBAL | SESSION
Com_check	numeric	GLOBAL | SESSION
Com_checksum	numeric	GLOBAL | SESSION
Com_commit	numeric	GLOBAL | SESSION
Com_create_db	numeric	GLOBAL | SESSION
Com_create_event	numeric	GLOBAL | SESSION
Com_create_function	numeric	GLOBAL | SESSION
Com_create_index	numeric	GLOBAL | SESSION
Com_create_table	numeric	GLOBAL | SESSION
Com_create_user	numeric	GLOBAL | SESSION
Com_dealloc_sql	numeric	GLOBAL | SESSION
Com_delete	numeric	GLOBAL | SESSION
Com_delete_multi	numeric	GLOBAL | SESSION
Com_do	numeric	GLOBAL | SESSION
Com_drop_db	numeric	GLOBAL | SESSION
Com_drop_event	numeric	GLOBAL | SESSION
Com_drop_function	numeric	GLOBAL | SESSION
Com_drop_index	numeric	GLOBAL | SESSION
Com_drop_table	numeric	GLOBAL | SESSION
Com_drop_user	numeric	GLOBAL | SESSION
Com_execute_sql	numeric	GLOBAL | SESSION
Com_flush	numeric	GLOBAL | SESSION
Com_grant	numeric	GLOBAL | SESSION
Com_ha_close	numeric	GLOBAL | SESSION
Com_ha_open	numeric	GLOBAL | SESSION
Com_ha_read	numeric	GLOBAL | SESSION
Com_help	numeric	GLOBAL | SESSION
Com_insert	numeric	GLOBAL | SESSION
Com_insert_select	numeric	GLOBAL | SESSION
Com_kill	numeric	GLOBAL | SESSION
Com_load	numeric	GLOBAL | SESSION
Com_lock_tables	numeric	GLOBAL | SESSION
Com_optimize	numeric	GLOBAL | SESSION
Com_preload_keys	numeric	GLOBAL | SESSION
Com_prepare_sql	numeric	GLOBAL | SESSION
Com_purge	numeric	GLOBAL | SESSION
Com_purge_before_date	numeric	GLOBAL | SESSION
Com_rename_table	numeric	GLOBAL | SESSION
Com_repair	numeric	GLOBAL | SESSION
Com_replace	numeric	GLOBAL | SESSION
Com_replace_select	numeric	GLOBAL | SESSION
Com_reset	numeric	GLOBAL | SESSION
Com_restore_table	numeric	GLOBAL | SESSION
Com_revoke	numeric	GLOBAL | SESSION
Com_revoke_all	numeric	GLOBAL | SESSION
Com_rollback	numeric	GLOBAL | SESSION
Com_savepoint	numeric	GLOBAL | SESSION
Com_select	numeric	GLOBAL | SESSION
Com_set_option	numeric	GLOBAL | SESSION
Com_show_binlog_events	numeric	GLOBAL | SESSION
Com_show_binlogs	numeric	GLOBAL | SESSION
Com_show_charsets	numeric	GLOBAL | SESSION
Com_show_collations	numeric	GLOBAL | SESSION
Com_show_column_types	numeric	GLOBAL | SESSION
Com_show_create_db	numeric	GLOBAL | SESSION
Com_show_create_event	numeric	GLOBAL | SESSION
Com_show_create_table	numeric	GLOBAL | SESSION
Com_show_databases	numeric	GLOBAL | SESSION
Com_show_engine_logs	numeric	GLOBAL | SESSION
Com_show_engine_mutex	numeric	GLOBAL | SESSION
Com_show_engine_status	numeric	GLOBAL | SESSION
Com_show_errors	numeric	GLOBAL | SESSION
Com_show_events	numeric	GLOBAL | SESSION
Com_show_fields	numeric	GLOBAL | SESSION
Com_show_grants	numeric	GLOBAL | SESSION
Com_show_innodb_status	numeric	GLOBAL | SESSION
Com_show_keys	numeric	GLOBAL | SESSION
Com_show_logs	numeric	GLOBAL | SESSION
Com_show_master_status	numeric	GLOBAL | SESSION
Com_show_ndb_status	numeric	GLOBAL | SESSION
Com_show_new_master	numeric	GLOBAL | SESSION
Com_show_open_tables	numeric	GLOBAL | SESSION
Com_show_plugins	numeric	GLOBAL | SESSION
Com_show_privileges	numeric	GLOBAL | SESSION
Com_show_processlist	numeric	GLOBAL | SESSION
Com_show_profile	numeric	GLOBAL | SESSION
Com_show_profiles	numeric	GLOBAL | SESSION
Com_show_slave_hosts	numeric	GLOBAL | SESSION
Com_show_slave_status	numeric	GLOBAL | SESSION
Com_show_status	numeric	GLOBAL | SESSION
Com_show_storage_engines	numeric	GLOBAL | SESSION
Com_show_tables	numeric	GLOBAL | SESSION
Com_show_triggers	numeric	GLOBAL | SESSION
Com_show_variables	numeric	GLOBAL | SESSION
Com_show_warnings	numeric	GLOBAL | SESSION
Com_slave_start	numeric	GLOBAL | SESSION
Com_slave_stop	numeric	GLOBAL | SESSION
Com_stmt_close	numeric	GLOBAL | SESSION
Com_stmt_execute	numeric	GLOBAL | SESSION
Com_stmt_fetch	numeric	GLOBAL | SESSION
Com_stmt_prepare	numeric	GLOBAL | SESSION
Com_stmt_reprepare	numeric	GLOBAL | SESSION
Com_stmt_reset	numeric	GLOBAL | SESSION
Com_stmt_send_long_data	numeric	GLOBAL | SESSION
Com_truncate	numeric	GLOBAL | SESSION
Com_unlock_tables	numeric	GLOBAL | SESSION
Com_update	numeric	GLOBAL | SESSION
Com_update_multi	numeric	GLOBAL | SESSION
Com_xa_commit	numeric	GLOBAL | SESSION
Com_xa_end	numeric	GLOBAL | SESSION
Com_xa_prepare	numeric	GLOBAL | SESSION
Com_xa_recover	numeric	GLOBAL | SESSION
Com_xa_rollback	numeric	GLOBAL | SESSION
Com_xa_start	numeric	GLOBAL | SESSION
Compression	numeric	SESSION
Connections	numeric	GLOBAL
Created_tmp_disk_tables	numeric	GLOBAL | SESSION
Created_tmp_files	numeric	GLOBAL
Created_tmp_tables	numeric	GLOBAL | SESSION
Delayed_errors	numeric	GLOBAL
Delayed_insert_threads	numeric	GLOBAL
Delayed_writes	numeric	GLOBAL
Flush_commands	numeric	GLOBAL
Handler_commit	numeric	GLOBAL | SESSION
Handler_delete	numeric	GLOBAL | SESSION
Handler_discover	numeric	GLOBAL | SESSION
Handler_prepare	numeric	GLOBAL | SESSION
Handler_read_first	numeric	GLOBAL | SESSION
Handler_read_key	numeric	GLOBAL | SESSION
Handler_read_next	numeric	GLOBAL | SESSION
Handler_read_prev	numeric	GLOBAL | SESSION
Handler_read_rnd	numeric	GLOBAL | SESSION
Handler_read_rnd_next	numeric	GLOBAL | SESSION
Handler_rollback	numeric	GLOBAL | SESSION
Handler_savepoint	numeric	GLOBAL | SESSION
Handler_savepoint_rollback	numeric	GLOBAL | SESSION
Handler_update	numeric	GLOBAL | SESSION
Handler_write	numeric	GLOBAL | SESSION
Innodb_buffer_pool_pages_data	numeric	GLOBAL
Innodb_buffer_pool_pages_dirty	numeric	GLOBAL
Innodb_buffer_pool_pages_flushed	numeric	GLOBAL
Innodb_buffer_pool_pages_free	numeric	GLOBAL
Innodb_buffer_pool_pages_latched	numeric	GLOBAL
Innodb_buffer_pool_pages_misc	numeric	GLOBAL
Innodb_buffer_pool_pages_total	numeric	GLOBAL
Innodb_buffer_pool_read_ahead_rnd	numeric	GLOBAL
Innodb_buffer_pool_read_ahead_seq	numeric	GLOBAL
Innodb_buffer_pool_read_requests	numeric	GLOBAL
Innodb_buffer_pool_reads	numeric	GLOBAL
Innodb_buffer_pool_wait_free	numeric	GLOBAL
Innodb_buffer_pool_write_requests	numeric	GLOBAL
Innodb_data_fsyncs	numeric	GLOBAL
Innodb_data_pending_fsyncs	numeric	GLOBAL
Innodb_data_pending_reads	numeric	GLOBAL
Innodb_data_pending_writes	numeric	GLOBAL
Innodb_data_read	numeric	GLOBAL
Innodb_data_reads	numeric	GLOBAL
Innodb_data_writes	numeric	GLOBAL
Innodb_data_written	numeric	GLOBAL
Innodb_dblwr_pages_written	numeric	GLOBAL
Innodb_dblwr_writes	numeric	GLOBAL
Innodb_log_waits	numeric	GLOBAL
Innodb_log_write_requests	numeric	GLOBAL
Innodb_log_writes	numeric	GLOBAL
Innodb_os_log_fsyncs	numeric	GLOBAL
Innodb_os_log_pending_fsyncs	numeric	GLOBAL
Innodb_os_log_pending_writes	numeric	GLOBAL
Innodb_os_log_written	numeric	GLOBAL
Innodb_page_size	numeric	GLOBAL
Innodb_pages_created	numeric	GLOBAL
Innodb_pages_read	numeric	GLOBAL
Innodb_pages_written	numeric	GLOBAL
Innodb_row_lock_current_waits	numeric	GLOBAL
Innodb_row_lock_time	numeric	GLOBAL
Innodb_row_lock_time_avg	numeric	GLOBAL
Innodb_row_lock_time_max	numeric	GLOBAL
Innodb_row_lock_waits	numeric	GLOBAL
Innodb_rows_deleted	numeric	GLOBAL
Innodb_rows_inserted	numeric	GLOBAL
Innodb_rows_read	numeric	GLOBAL
Innodb_rows_updated	numeric	GLOBAL
Key_blocks_not_flushed	numeric	GLOBAL
Key_blocks_unused	numeric	GLOBAL
Key_blocks_used	numeric	GLOBAL
Key_read_requests	numeric	GLOBAL
Key_reads	numeric	GLOBAL
Key_write_requests	numeric	GLOBAL
Key_writes	numeric	GLOBAL
Last_query_cost	numeric	SESSION
Max_used_connections	numeric	GLOBAL
ndb-cluster-connection-pool	numeric	GLOBAL
Ndb_cluster_node_id	numeric	GLOBAL | SESSION
Ndb_config_from_host	numeric	GLOBAL | SESSION
Ndb_config_from_port	numeric	GLOBAL | SESSION
Ndb_conflict_fn_max	numeric	GLOBAL
Ndb_conflict_fn_old	numeric	GLOBAL
ndb_execute_count	numeric	GLOBAL
ndb-nodeid	numeric	GLOBAL
Ndb_number_of_data_nodes	numeric	GLOBAL
ndb_pruned_scan_count	numeric	GLOBAL
ndb_scan_count	numeric	GLOBAL
Not_flushed_delayed_rows	numeric	GLOBAL
Open_files	numeric	GLOBAL
Open_streams	numeric	GLOBAL
Open_table_definitions	numeric	GLOBAL
Open_tables	numeric	GLOBAL | SESSION
Opened_files	numeric	GLOBAL
Opened_table_definitions	numeric	GLOBAL | SESSION
Opened_tables	numeric	GLOBAL | SESSION
Prepared_stmt_count	numeric	GLOBAL
Qcache_free_blocks	numeric	GLOBAL
Qcache_free_memory	numeric	GLOBAL
Qcache_hits	numeric	GLOBAL
Qcache_inserts	numeric	GLOBAL
Qcache_lowmem_prunes	numeric	GLOBAL
Qcache_not_cached	numeric	GLOBAL
Qcache_queries_in_cache	numeric	GLOBAL
Qcache_total_blocks	numeric	GLOBAL
Queries	numeric	GLOBAL | SESSION
Questions	numeric	GLOBAL | SESSION
Rpl_status	string	GLOBAL
Select_full_join	numeric	GLOBAL | SESSION
Select_full_range_join	numeric	GLOBAL | SESSION
Select_range	numeric	GLOBAL | SESSION
Select_range_check	numeric	GLOBAL | SESSION
Select_scan	numeric	GLOBAL | SESSION
Slave_heartbeat_period		GLOBAL
Slave_open_temp_tables	numeric	GLOBAL
Slave_received_heartbeats		GLOBAL
Slave_retried_transactions	numeric	GLOBAL
Slave_running	boolean	GLOBAL
Slow_launch_threads	numeric	GLOBAL | SESSION
Slow_queries	numeric	GLOBAL | SESSION
Sort_merge_passes	numeric	GLOBAL | SESSION
Sort_range	numeric	GLOBAL | SESSION
Sort_rows	numeric	GLOBAL | SESSION
Sort_scan	numeric	GLOBAL | SESSION
Ssl_accept_renegotiates	numeric	GLOBAL
Ssl_accepts	numeric	GLOBAL
Ssl_callback_cache_hits	numeric	GLOBAL
Ssl_cipher	string	GLOBAL | SESSION
Ssl_cipher_list	string	GLOBAL | SESSION
Ssl_client_connects	numeric	GLOBAL
Ssl_connect_renegotiates	numeric	GLOBAL
Ssl_ctx_verify_depth	numeric	GLOBAL
Ssl_ctx_verify_mode	numeric	GLOBAL
Ssl_default_timeout	numeric	GLOBAL | SESSION
Ssl_finished_accepts	numeric	GLOBAL
Ssl_finished_connects	numeric	GLOBAL
Ssl_session_cache_hits	numeric	GLOBAL
Ssl_session_cache_misses	numeric	GLOBAL
Ssl_session_cache_mode	string	GLOBAL
Ssl_session_cache_overflows	numeric	GLOBAL
Ssl_session_cache_size	numeric	GLOBAL
Ssl_session_cache_timeouts	numeric	GLOBAL
Ssl_sessions_reused	numeric	GLOBAL | SESSION
Ssl_used_session_cache_entries	numeric	GLOBAL
Ssl_verify_depth	numeric	GLOBAL | SESSION
Ssl_verify_mode	numeric	GLOBAL | SESSION
Ssl_version	string	GLOBAL | SESSION
Table_locks_immediate	numeric	GLOBAL
Table_locks_waited	numeric	GLOBAL
Tc_log_max_pages_used	numeric	GLOBAL
Tc_log_page_size	numeric	GLOBAL
Tc_log_page_waits	numeric	GLOBAL
Threads_cached	numeric	GLOBAL
Threads_connected	numeric	GLOBAL
Threads_created	numeric	GLOBAL
Threads_running	numeric	GLOBAL
Uptime	numeric	GLOBAL
Uptime_since_flush_status	numeric	GLOBAL

Many status variables are reset to 0 by the FLUSH STATUS statement.

MySQL Enterprise.  For expert advice on using status variables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

The status variables have the following meanings. Variables with no version indicated were already present prior to MySQL 5.1. For information regarding their implementation history, see MySQL 5.0 Reference Manual.

• Aborted_clients

  The number of connections that were aborted because the client died without closing the connection properly. See Section B.1.2.11, “Communication Errors and Aborted Connections”.

• Aborted_connects

  The number of failed attempts to connect to the MySQL server. See Section B.1.2.11, “Communication Errors and Aborted Connections”.

• Binlog_cache_disk_use

  The number of transactions that used the temporary binary log cache but that exceeded the value of binlog_cache_size and used a temporary file to store statements from the transaction.

• Binlog_cache_use

  The number of transactions that used the temporary binary log cache.

• Bytes_received

  The number of bytes received from all clients.

• Bytes_sent

  The number of bytes sent to all clients.

• Com_xxx

  The Com_xxx statement counter variables indicate the number of times each xxx statement has been executed. There is one status variable for each type of statement. For example, Com_delete and Com_insert count DELETE and INSERT statements, respectively. However, if a query result is returned from query cache, the server increments the Qcache_hits status variable, not Com_select. See Section 7.5.5.4, “Query Cache Status and Maintenance”.

  All of the Com_stmt_xxx variables are increased even if a prepared statement argument is unknown or an error occurred during execution. In other words, their values correspond to the number of requests issued, not to the number of requests successfully completed.

  The Com_stmt_xxx status variables are as follows:

  • Com_stmt_prepare

  • Com_stmt_execute

  • Com_stmt_fetch

  • Com_stmt_send_long_data

  • Com_stmt_reset

  • Com_stmt_close

  Those variables stand for prepared statement commands. Their names refer to the COM_xxx command set used in the network layer. In other words, their values increase whenever prepared statement API calls such as mysql_stmt_prepare(), mysql_stmt_execute(), and so forth are executed. However, Com_stmt_prepare, Com_stmt_execute and Com_stmt_close also increase for PREPARE, EXECUTE, or DEALLOCATE PREPARE, respectively. Additionally, the values of the older (available since MySQL 4.1.3) statement counter variables Com_prepare_sql, Com_execute_sql, and Com_dealloc_sql increase for the PREPARE, EXECUTE, and DEALLOCATE PREPARE statements. Com_stmt_fetch stands for the total number of network round-trips issued when fetching from cursors.

  Com_stmt_reprepare indicated the number of times statements were automatically reprepared by the server after metadata changes to tables or views referred to by the statement. This variable was added in MySQL 5.1.25. A reprepare operation increments Com_stmt_reprepare is incremented, and also Com_stmt_prepare.

• Compression

  Whether the client connection uses compression in the client/server protocol. Added in MySQL 5.1.2.

• Connections

  The number of connection attempts (successful or not) to the MySQL server.

• Created_tmp_disk_tables

  The number of temporary tables on disk created automatically by the server while executing statements.

• Created_tmp_files

  How many temporary files mysqld has created.

• Created_tmp_tables

  The number of in-memory temporary tables created automatically by the server while executing statements. If Created_tmp_disk_tables is large, you may want to increase the tmp_table_size value to cause temporary tables to be memory-based instead of disk-based.

• Delayed_errors

  The number of rows written with INSERT DELAYED for which some error occurred (probably duplicate key).

• Delayed_insert_threads

  The number of INSERT DELAYED handler threads in use.

• Delayed_writes

  The number of INSERT DELAYED rows written.

• Flush_commands

  The number of executed FLUSH statements.

• Handler_commit

  The number of internal COMMIT statements.

• Handler_delete

  The number of times that rows have been deleted from tables.

• Handler_prepare

  A counter for the prepare phase of two-phase commit operations.

• Handler_read_first

  The number of times the first entry was read from an index. If this value is high, it suggests that the server is doing a lot of full index scans; for example, SELECT col1 FROM foo, assuming that col1 is indexed.

• Handler_read_key

  The number of requests to read a row based on a key. If this value is high, it is a good indication that your tables are properly indexed for your queries.

• Handler_read_next

  The number of requests to read the next row in key order. This value is incremented if you are querying an index column with a range constraint or if you are doing an index scan.

• Handler_read_prev

  The number of requests to read the previous row in key order. This read method is mainly used to optimize ORDER BY ... DESC.

• Handler_read_rnd

  The number of requests to read a row based on a fixed position. This value is high if you are doing a lot of queries that require sorting of the result. You probably have a lot of queries that require MySQL to scan entire tables or you have joins that don't use keys properly.

• Handler_read_rnd_next

  The number of requests to read the next row in the data file. This value is high if you are doing a lot of table scans. Generally this suggests that your tables are not properly indexed or that your queries are not written to take advantage of the indexes you have.

• Handler_rollback

  The number of requests for a storage engine to perform a rollback operation.

• Handler_savepoint

  The number of requests for a storage engine to place a savepoint.

• Handler_savepoint_rollback

  The number of requests for a storage engine to roll back to a savepoint.

• Handler_update

  The number of requests to update a row in a table.

• Handler_write

  The number of requests to insert a row in a table.

• Innodb_buffer_pool_pages_data

  The number of pages containing data (dirty or clean).

• Innodb_buffer_pool_pages_dirty

  The number of pages currently dirty.

• Innodb_buffer_pool_pages_flushed

  The number of buffer pool page-flush requests.

• Innodb_buffer_pool_pages_free

  The number of free pages.

• Innodb_buffer_pool_pages_latched

  The number of latched pages in InnoDB buffer pool. These are pages currently being read or written or that cannot be flushed or removed for some other reason. Calculation of this variable is expensive, so as of MySQL 5.1.28, it is available only when the UNIV_DEBUG system is defined at server build time.

• Innodb_buffer_pool_pages_misc

  The number of pages that are busy because they have been allocated for administrative overhead such as row locks or the adaptive hash index. This value can also be calculated as Innodb_buffer_pool_pages_total – Innodb_buffer_pool_pages_free – Innodb_buffer_pool_pages_data.

• Innodb_buffer_pool_pages_total

  The total size of the buffer pool, in pages.

• Innodb_buffer_pool_read_ahead_rnd

  The number of “random” read-aheads initiated by InnoDB. This happens when a query scans a large portion of a table but in random order.

• Innodb_buffer_pool_read_ahead_seq

  The number of sequential read-aheads initiated by InnoDB. This happens when InnoDB does a sequential full table scan.

• Innodb_buffer_pool_read_requests

  The number of logical read requests InnoDB has done.

• Innodb_buffer_pool_reads

  The number of logical reads that InnoDB could not satisfy from the buffer pool and had to do a single-page read.

• Innodb_buffer_pool_wait_free

  Normally, writes to the InnoDB buffer pool happen in the background. However, if it is necessary to read or create a page and no clean pages are available, it is also necessary to wait for pages to be flushed first. This counter counts instances of these waits. If the buffer pool size has been set properly, this value should be small.

• Innodb_buffer_pool_write_requests

  The number writes done to the InnoDB buffer pool.

• Innodb_data_fsyncs

  The number of fsync() operations so far.

• Innodb_data_pending_fsyncs

  The current number of pending fsync() operations.

• Innodb_data_pending_reads

  The current number of pending reads.

• Innodb_data_pending_writes

  The current number of pending writes.

• Innodb_data_read

  The amount of data read so far, in bytes.

• Innodb_data_reads

  The total number of data reads.

• Innodb_data_writes

  The total number of data writes.

• Innodb_data_written

  The amount of data written so far, in bytes.

• Innodb_dblwr_pages_written

  The number of pages that have been written for doublewrite operations. See Section 13.6.11.1, “InnoDB Disk I/O”.

• Innodb_dblwr_writes

  The number of doublewrite operations that have been performed. See Section 13.6.11.1, “InnoDB Disk I/O”.

• Innodb_log_waits

  The number of times that the log buffer was too small and a wait was required for it to be flushed before continuing.

• Innodb_log_write_requests

  The number of log write requests.

• Innodb_log_writes

  The number of physical writes to the log file.

• Innodb_os_log_fsyncs

  The number of fsync() writes done to the log file.

• Innodb_os_log_pending_fsyncs

  The number of pending log file fsync() operations.

• Innodb_os_log_pending_writes

  The number of pending log file writes.

• Innodb_os_log_written

  The number of bytes written to the log file.

• Innodb_page_size

  The compiled-in InnoDB page size (default 16KB). Many values are counted in pages; the page size allows them to be easily converted to bytes.

• Innodb_pages_created

  The number of pages created.

• Innodb_pages_read

  The number of pages read.

• Innodb_pages_written

  The number of pages written.

• Innodb_row_lock_current_waits

  The number of row locks currently being waited for.

• Innodb_row_lock_time

  The total time spent in acquiring row locks, in milliseconds.

• Innodb_row_lock_time_avg

  The average time to acquire a row lock, in milliseconds.

• Innodb_row_lock_time_max

  The maximum time to acquire a row lock, in milliseconds.

• Innodb_row_lock_waits

  The number of times a row lock had to be waited for.

• Innodb_rows_deleted

  The number of rows deleted from InnoDB tables.

• Innodb_rows_inserted

  The number of rows inserted into InnoDB tables.

• Innodb_rows_read

  The number of rows read from InnoDB tables.

• Innodb_rows_updated

  The number of rows updated in InnoDB tables.

• Key_blocks_not_flushed

  The number of key blocks in the key cache that have changed but have not yet been flushed to disk.

• Key_blocks_unused

  The number of unused blocks in the key cache. You can use this value to determine how much of the key cache is in use; see the discussion of key_buffer_size in Section 5.1.3, “Server System Variables”.

• Key_blocks_used

  The number of used blocks in the key cache. This value is a high-water mark that indicates the maximum number of blocks that have ever been in use at one time.

• Key_read_requests

  The number of requests to read a key block from the cache.

• Key_reads

  The number of physical reads of a key block from disk. If Key_reads is large, then your key_buffer_size value is probably too small. The cache miss rate can be calculated as Key_reads/Key_read_requests.

• Key_write_requests

  The number of requests to write a key block to the cache.

• Key_writes

  The number of physical writes of a key block to disk.

• Last_query_cost

  The total cost of the last compiled query as computed by the query optimizer. This is useful for comparing the cost of different query plans for the same query. The default value of 0 means that no query has been compiled yet. The default value is 0. Last_query_cost has session scope.

  The Last_query_cost value can be computed accurately only for simple “flat” queries, not complex queries such as those with subqueries or UNION. For the latter, the value is set to 0.

• Max_used_connections

  The maximum number of connections that have been in use simultaneously since the server started.

• Not_flushed_delayed_rows

  The number of rows waiting to be written in INSERT DELAY queues.

• Open_files

  The number of files that are open. This count includes regular files opened by the server. It does not include other types of files such as sockets or pipes. Also, the count does not include files that storage engines open using their own internal functions rather than asking the server level to do so.

• Open_streams

  The number of streams that are open (used mainly for logging).

• Open_table_definitions

  The number of cached .frm files. This variable was added in MySQL 5.1.3.

• Open_tables

  The number of tables that are open.

• Opened_files

  The number of files that have been opened with my_open() (a mysys library function). Parts of the server that open files without using this function do not increment the count. This variable was added in MySQL 5.1.21.

• Opened_table_definitions

  The number of .frm files that have been cached. This variable was added in MySQL 5.1.24.

• Opened_tables

  The number of tables that have been opened. If Opened_tables is big, your table_open_cache value is probably too small.

• Prepared_stmt_count

  The current number of prepared statements. (The maximum number of statements is given by the max_prepared_stmt_count system variable.) This variable was added in MySQL 5.1.14.

• Qcache_free_blocks

  The number of free memory blocks in the query cache.

• Qcache_free_memory

  The amount of free memory for the query cache.

• Qcache_hits

  The number of query cache hits.

• Qcache_inserts

  The number of queries added to the query cache.

• Qcache_lowmem_prunes

  The number of queries that were deleted from the query cache because of low memory.

• Qcache_not_cached

  The number of non-cached queries (not cacheable, or not cached due to the query_cache_type setting).

• Qcache_queries_in_cache

  The number of queries registered in the query cache.

• Qcache_total_blocks

  The total number of blocks in the query cache.

• Queries

  The number of statements executed by the server. This variable includes statements executed within stored programs, unlike the Questions variable. This variable was added in MySQL 5.1.31.

• Questions

  The number of statements executed by the server. As of MySQL 5.1.31, this includes only statements sent to the server by clients and no longer includes statements executed within stored programs, unlike the Queries variable.

• Rpl_status

  The status of fail-safe replication (not yet implemented).

• Select_full_join

  The number of joins that perform table scans because they do not use indexes. If this value is not 0, you should carefully check the indexes of your tables.

• Select_full_range_join

  The number of joins that used a range search on a reference table.

• Select_range

  The number of joins that used ranges on the first table. This is normally not a critical issue even if the value is quite large.

• Select_range_check

  The number of joins without keys that check for key usage after each row. If this is not 0, you should carefully check the indexes of your tables.

• Select_scan

  The number of joins that did a full scan of the first table.

• Slave_open_temp_tables

  The number of temporary tables that the slave SQL thread currently has open.

• Slave_retried_transactions

  The total number of times since startup that the replication slave SQL thread has retried transactions.

• Slave_running

  This is ON if this server is a replication slave that is connected to a replication master, and both the I/O and SQL threads are running; otherwise, it is OFF.

• Slow_launch_threads

  The number of threads that have taken more than slow_launch_time seconds to create.

• Slow_queries

  The number of queries that have taken more than long_query_time seconds. See Section 5.2.5, “The Slow Query Log”.

• Sort_merge_passes

  The number of merge passes that the sort algorithm has had to do. If this value is large, you should consider increasing the value of the sort_buffer_size system variable.

• Sort_range

  The number of sorts that were done using ranges.

• Sort_rows

  The number of sorted rows.

• Sort_scan

  The number of sorts that were done by scanning the table.

• Ssl_accept_renegotiates

  The number of negotiates needed to establish the connection.

• Ssl_accepts

  The number of accepted SSL connections.

• Ssl_callback_cache_hits

  The number of callback cache hits.

• Ssl_cipher

  The current SSL cipher (empty for non-SSL connections).

• Ssl_cipher_list

  The list of possible SSL ciphers.

• Ssl_client_connects

  The number of SSL connection attempts to an SSL-enabled master.

• Ssl_connect_renegotiates

  The number of negotiates needed to establish the connection to an SSL-enabled master.

• Ssl_ctx_verify_depth

  The SSL context verification depth (how many certificates in the chain are tested).

• Ssl_ctx_verify_mode

  The SSL context verification mode.

• Ssl_default_timeout

  The default SSL timeout.

• Ssl_finished_accepts

  The number of successful SSL connections to the server.

• Ssl_finished_connects

  The number of successful slave connections to an SSL-enabled master.

• Ssl_session_cache_hits

  The number of SSL session cache hits.

• Ssl_session_cache_misses

  The number of SSL session cache misses.

• Ssl_session_cache_mode

  The SSL session cache mode.

• Ssl_session_cache_overflows

  The number of SSL session cache overflows.

• Ssl_session_cache_size

  The SSL session cache size.

• Ssl_session_cache_timeouts

  The number of SSL session cache timeouts.

• Ssl_sessions_reused

  How many SSL connections were reused from the cache.

• Ssl_used_session_cache_entries

  How many SSL session cache entries were used.

• Ssl_verify_depth

  The verification depth for replication SSL connections.

• Ssl_verify_mode

  The verification mode for replication SSL connections.

• Ssl_version

  The SSL version number.

• Table_locks_immediate

  The number of times that a request for a table lock could be granted immediately.

• Table_locks_waited

  The number of times that a request for a table lock could not be granted immediately and a wait was needed. If this is high and you have performance problems, you should first optimize your queries, and then either split your table or tables or use replication.

• Tc_log_max_pages_used

  For the memory-mapped implementation of the log that is used by mysqld when it acts as the transaction coordinator for recovery of internal XA transactions, this variable indicates the largest number of pages used for the log since the server started. If the product of Tc_log_max_pages_used and Tc_log_page_size is always significantly less than the log size, the size is larger than necessary and can be reduced. (The size is set by the --log-tc-size option. Currently, this variable is unused: It is unneeded for binary log-based recovery, and the memory-mapped recovery log method is not used unless the number of storage engines capable of two-phase commit is greater than one. (InnoDB is the only applicable engine.)

• Tc_log_page_size

  The page size used for the memory-mapped implementation of the XA recovery log. The default value is determined using getpagesize(). Currently, this variable is unused for the same reasons as described for Tc_log_max_pages_used.

• Tc_log_page_waits

  For the memory-mapped implementation of the recovery log, this variable increments each time the server was not able to commit a transaction and had to wait for a free page in the log. If this value is large, you might want to increase the log size (with the --log-tc-size option). For binary log-based recovery, this variable increments each time the binary log cannot be closed because there are two-phase commits in progress. (The close operation waits until all such transactions are finished.)

• Threads_cached

  The number of threads in the thread cache.

• Threads_connected

  The number of currently open connections.

• Threads_created

  The number of threads created to handle connections. If Threads_created is big, you may want to increase the thread_cache_size value. The cache miss rate can be calculated as Threads_created/Connections.

• Threads_running

  The number of threads that are not sleeping.

• Uptime

  The number of seconds that the server has been up.

• Uptime_since_flush_status

  The number of seconds since the most recent FLUSH STATUS statement. This variable was added in 5.1.24.