5.1.6. Server Status Variables

5.1.6. 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 13.7.5.32, “SHOW STATUS Syntax”). The optional GLOBAL keyword aggregates the values over all connections, and SESSIONshows 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    |+-----------------------------------+------------+

Note

Before MySQL 5.0.2, SHOW STATUS returned global status values. Because the default as of 5.0.2 is to return session values, this is incompatible with previous versions. To issue a SHOW STATUS statement that will retrieve global status values for all versions of MySQL, write it like this:

SHOW /*!50002 GLOBAL */ STATUS;

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

The following table lists all available server status variables:

Table 5.4. Status Variable Summary

Variable NameVariable TypeVariable ScopeAborted_clientsnumericGLOBALAborted_connectsnumericGLOBALBinlog_cache_disk_usenumericGLOBALBinlog_cache_usenumericGLOBALBytes_receivednumericGLOBAL | SESSIONBytes_sentnumericGLOBAL | SESSIONCom_admin_commandsnumericGLOBAL | SESSIONCom_alter_dbnumericGLOBAL | SESSIONCom_alter_eventnumericGLOBAL | SESSIONCom_alter_tablenumericGLOBAL | SESSIONCom_analyzenumericGLOBAL | SESSIONCom_backup_tablenumericGLOBAL | SESSIONCom_beginnumericGLOBAL | SESSIONCom_call_procedurenumericGLOBAL | SESSIONCom_change_dbnumericGLOBAL | SESSIONCom_change_masternumericGLOBAL | SESSIONCom_checknumericGLOBAL | SESSIONCom_checksumnumericGLOBAL | SESSIONCom_commitnumericGLOBAL | SESSIONCom_create_dbnumericGLOBAL | SESSIONCom_create_eventnumericGLOBAL | SESSIONCom_create_functionnumericGLOBAL | SESSIONCom_create_indexnumericGLOBAL | SESSIONCom_create_tablenumericGLOBAL | SESSIONCom_create_usernumericGLOBAL | SESSIONCom_dealloc_sqlnumericGLOBAL | SESSIONCom_deletenumericGLOBAL | SESSIONCom_delete_multinumericGLOBAL | SESSIONCom_donumericGLOBAL | SESSIONCom_drop_dbnumericGLOBAL | SESSIONCom_drop_eventnumericGLOBAL | SESSIONCom_drop_functionnumericGLOBAL | SESSIONCom_drop_indexnumericGLOBAL | SESSIONCom_drop_tablenumericGLOBAL | SESSIONCom_drop_usernumericGLOBAL | SESSIONCom_execute_sqlnumericGLOBAL | SESSIONCom_flushnumericGLOBAL | SESSIONCom_grantnumericGLOBAL | SESSIONCom_ha_closenumericGLOBAL | SESSIONCom_ha_opennumericGLOBAL | SESSIONCom_ha_readnumericGLOBAL | SESSIONCom_helpnumericGLOBAL | SESSIONCom_insertnumericGLOBAL | SESSIONCom_insert_selectnumericGLOBAL | SESSIONCom_killnumericGLOBAL | SESSIONCom_loadnumericGLOBAL | SESSIONCom_lock_tablesnumericGLOBAL | SESSIONCom_optimizenumericGLOBAL | SESSIONCom_preload_keysnumericGLOBAL | SESSIONCom_prepare_sqlnumericGLOBAL | SESSIONCom_purgenumericGLOBAL | SESSIONCom_purge_before_datenumericGLOBAL | SESSIONCom_rename_tablenumericGLOBAL | SESSIONCom_repairnumericGLOBAL | SESSIONCom_replacenumericGLOBAL | SESSIONCom_replace_selectnumericGLOBAL | SESSIONCom_resetnumericGLOBAL | SESSIONCom_restore_tablenumericGLOBAL | SESSIONCom_revokenumericGLOBAL | SESSIONCom_revoke_allnumericGLOBAL | SESSIONCom_rollbacknumericGLOBAL | SESSIONCom_savepointnumericGLOBAL | SESSIONCom_selectnumericGLOBAL | SESSIONCom_set_optionnumericGLOBAL | SESSIONCom_show_binlog_eventsnumericGLOBAL | SESSIONCom_show_binlogsnumericGLOBAL | SESSIONCom_show_charsetsnumericGLOBAL | SESSIONCom_show_collationsnumericGLOBAL | SESSIONCom_show_column_typesnumericGLOBAL | SESSIONCom_show_create_dbnumericGLOBAL | SESSIONCom_show_create_eventnumericGLOBAL | SESSIONCom_show_create_tablenumericGLOBAL | SESSIONCom_show_databasesnumericGLOBAL | SESSIONCom_show_engine_logsnumericGLOBAL | SESSIONCom_show_engine_mutexnumericGLOBAL | SESSIONCom_show_engine_statusnumericGLOBAL | SESSIONCom_show_errorsnumericGLOBAL | SESSIONCom_show_eventsnumericGLOBAL | SESSIONCom_show_fieldsnumericGLOBAL | SESSIONCom_show_grantsnumericGLOBAL | SESSIONCom_show_innodb_statusnumericGLOBAL | SESSIONCom_show_keysnumericGLOBAL | SESSIONCom_show_logsnumericGLOBAL | SESSIONCom_show_master_statusnumericGLOBAL | SESSIONCom_show_ndb_statusnumericGLOBAL | SESSIONCom_show_new_masternumericGLOBAL | SESSIONCom_show_open_tablesnumericGLOBAL | SESSIONCom_show_pluginsnumericGLOBAL | SESSIONCom_show_privilegesnumericGLOBAL | SESSIONCom_show_processlistnumericGLOBAL | SESSIONCom_show_slave_hostsnumericGLOBAL | SESSIONCom_show_slave_statusnumericGLOBAL | SESSIONCom_show_statusnumericGLOBAL | SESSIONCom_show_storage_enginesnumericGLOBAL | SESSIONCom_show_tablesnumericGLOBAL | SESSIONCom_show_triggersnumericGLOBAL | SESSIONCom_show_variablesnumericGLOBAL | SESSIONCom_show_warningsnumericGLOBAL | SESSIONCom_slave_startnumericGLOBAL | SESSIONCom_slave_stopnumericGLOBAL | SESSIONCom_stmt_closenumericGLOBAL | SESSIONCom_stmt_executenumericGLOBAL | SESSIONCom_stmt_fetchnumericGLOBAL | SESSIONCom_stmt_preparenumericGLOBAL | SESSIONCom_stmt_resetnumericGLOBAL | SESSIONCom_stmt_send_long_datanumericGLOBAL | SESSIONCom_truncatenumericGLOBAL | SESSIONCom_unlock_tablesnumericGLOBAL | SESSIONCom_updatenumericGLOBAL | SESSIONCom_update_multinumericGLOBAL | SESSIONCom_xa_commitnumericGLOBAL | SESSIONCom_xa_endnumericGLOBAL | SESSIONCom_xa_preparenumericGLOBAL | SESSIONCom_xa_recovernumericGLOBAL | SESSIONCom_xa_rollbacknumericGLOBAL | SESSIONCom_xa_startnumericGLOBAL | SESSIONCompressionnumericSESSIONConnectionsnumericGLOBALCreated_tmp_disk_tablesnumericGLOBAL | SESSIONCreated_tmp_filesnumericGLOBALCreated_tmp_tablesnumericGLOBAL | SESSIONDelayed_errorsnumericGLOBALDelayed_insert_threadsnumericGLOBALDelayed_writesnumericGLOBALFlush_commandsnumericGLOBALHandler_commitnumericGLOBAL | SESSIONHandler_deletenumericGLOBAL | SESSIONHandler_discovernumericGLOBAL | SESSIONHandler_preparenumericGLOBAL | SESSIONHandler_read_firstnumericGLOBAL | SESSIONHandler_read_keynumericGLOBAL | SESSIONHandler_read_nextnumericGLOBAL | SESSIONHandler_read_prevnumericGLOBAL | SESSIONHandler_read_rndnumericGLOBAL | SESSIONHandler_read_rnd_nextnumericGLOBAL | SESSIONHandler_rollbacknumericGLOBAL | SESSIONHandler_savepointnumericGLOBAL | SESSIONHandler_savepoint_rollbacknumericGLOBAL | SESSIONHandler_updatenumericGLOBAL | SESSIONHandler_writenumericGLOBAL | SESSIONInnodb_buffer_pool_pages_datanumericGLOBALInnodb_buffer_pool_pages_dirtynumericGLOBALInnodb_buffer_pool_pages_flushednumericGLOBALInnodb_buffer_pool_pages_freenumericGLOBALInnodb_buffer_pool_pages_latchednumericGLOBALInnodb_buffer_pool_pages_miscnumericGLOBALInnodb_buffer_pool_pages_totalnumericGLOBALInnodb_buffer_pool_read_ahead_rndnumericGLOBALInnodb_buffer_pool_read_ahead_seqnumericGLOBALInnodb_buffer_pool_read_requestsnumericGLOBALInnodb_buffer_pool_readsnumericGLOBALInnodb_buffer_pool_wait_freenumericGLOBALInnodb_buffer_pool_write_requestsnumericGLOBALInnodb_data_fsyncsnumericGLOBALInnodb_data_pending_fsyncsnumericGLOBALInnodb_data_pending_readsnumericGLOBALInnodb_data_pending_writesnumericGLOBALInnodb_data_readnumericGLOBALInnodb_data_readsnumericGLOBALInnodb_data_writesnumericGLOBALInnodb_data_writtennumericGLOBALInnodb_dblwr_pages_writtennumericGLOBALInnodb_dblwr_writesnumericGLOBALInnodb_log_waitsnumericGLOBALInnodb_log_write_requestsnumericGLOBALInnodb_log_writesnumericGLOBALInnodb_os_log_fsyncsnumericGLOBALInnodb_os_log_pending_fsyncsnumericGLOBALInnodb_os_log_pending_writesnumericGLOBALInnodb_os_log_writtennumericGLOBALInnodb_page_sizenumericGLOBALInnodb_pages_creatednumericGLOBALInnodb_pages_readnumericGLOBALInnodb_pages_writtennumericGLOBALInnodb_row_lock_current_waitsnumericGLOBALInnodb_row_lock_timenumericGLOBALInnodb_row_lock_time_avgnumericGLOBALInnodb_row_lock_time_maxnumericGLOBALInnodb_row_lock_waitsnumericGLOBALInnodb_rows_deletednumericGLOBALInnodb_rows_insertednumericGLOBALInnodb_rows_readnumericGLOBALInnodb_rows_updatednumericGLOBALKey_blocks_not_flushednumericGLOBALKey_blocks_unusednumericGLOBALKey_blocks_usednumericGLOBALKey_read_requestsnumericGLOBALKey_readsnumericGLOBALKey_write_requestsnumericGLOBALKey_writesnumericGLOBALLast_query_costnumericSESSIONMax_used_connectionsnumericGLOBALNdb_cluster_node_idnumericGLOBAL | SESSIONNdb_config_from_hostnumericGLOBAL | SESSIONNdb_config_from_portnumericGLOBAL | SESSIONndb-nodeidnumericGLOBALNot_flushed_delayed_rowsnumericGLOBALOpen_filesnumericGLOBALOpen_streamsnumericGLOBALOpen_tablesnumericGLOBAL | SESSIONOpened_tablesnumericGLOBAL | SESSIONPrepared_stmt_countnumericGLOBALQcache_free_blocksnumericGLOBALQcache_free_memorynumericGLOBALQcache_hitsnumericGLOBALQcache_insertsnumericGLOBALQcache_lowmem_prunesnumericGLOBALQcache_not_cachednumericGLOBALQcache_queries_in_cachenumericGLOBALQcache_total_blocksnumericGLOBALQueriesnumericGLOBAL | SESSIONQuestionsnumericGLOBAL | SESSIONRpl_statusstringGLOBALSelect_full_joinnumericGLOBAL | SESSIONSelect_full_range_joinnumericGLOBAL | SESSIONSelect_rangenumericGLOBAL | SESSIONSelect_range_checknumericGLOBAL | SESSIONSelect_scannumericGLOBAL | SESSIONSlave_open_temp_tablesnumericGLOBALSlave_retried_transactionsnumericGLOBALSlave_runningbooleanGLOBALSlow_launch_threadsnumericGLOBAL | SESSIONSlow_queriesnumericGLOBAL | SESSIONSort_merge_passesnumericGLOBAL | SESSIONSort_rangenumericGLOBAL | SESSIONSort_rowsnumericGLOBAL | SESSIONSort_scannumericGLOBAL | SESSIONSsl_accept_renegotiatesnumericGLOBALSsl_acceptsnumericGLOBALSsl_callback_cache_hitsnumericGLOBALSsl_cipherstringGLOBAL | SESSIONSsl_cipher_liststringGLOBAL | SESSIONSsl_client_connectsnumericGLOBALSsl_connect_renegotiatesnumericGLOBALSsl_ctx_verify_depthnumericGLOBALSsl_ctx_verify_modenumericGLOBALSsl_default_timeoutnumericGLOBAL | SESSIONSsl_finished_acceptsnumericGLOBALSsl_finished_connectsnumericGLOBALSsl_session_cache_hitsnumericGLOBALSsl_session_cache_missesnumericGLOBALSsl_session_cache_modestringGLOBALSsl_session_cache_overflowsnumericGLOBALSsl_session_cache_sizenumericGLOBALSsl_session_cache_timeoutsnumericGLOBALSsl_sessions_reusednumericGLOBAL | SESSIONSsl_used_session_cache_entriesnumericGLOBALSsl_verify_depthnumericGLOBAL | SESSIONSsl_verify_modenumericGLOBAL | SESSIONSsl_versionstringGLOBAL | SESSIONTable_locks_immediatenumericGLOBALTable_locks_waitednumericGLOBALTc_log_max_pages_usednumericGLOBALTc_log_page_sizenumericGLOBALTc_log_page_waitsnumericGLOBALThreads_cachednumericGLOBALThreads_connectednumericGLOBALThreads_creatednumericGLOBALThreads_runningnumericGLOBALUptimenumericGLOBALUptime_since_flush_statusnumericGLOBAL

The status variables have the following meanings. For meanings of status variables specific to MySQL Cluster, see Section 17.3.4.4, “MySQL Cluster Status Variables”.

•  Aborted_clients

  The number of connections that were aborted because the client died without closing the connection properly. SeeSection C.5.2.11, “Communication Errors and Aborted Connections”.

•  Aborted_connects

  The number of failed attempts to connect to the MySQL server. See Section C.5.2.11, “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 ofbinlog_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 countDELETE 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 8.6.3.4, “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 were added in 5.0.8:

  • 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 asmysql_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 statement counter variables Com_prepare_sql,Com_execute_sql, and Com_dealloc_sql increase for the PREPARE, EXECUTE, and DEALLOCATE PREPAREstatements. Com_stmt_fetch stands for the total number of network round-trips issued when fetching from cursors.

•  Compression

  Whether the client connection uses compression in the client/server protocol. Added in MySQL 5.0.16.

•  Connections

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

•  Created_tmp_disk_tables

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

  If an internal temporary table is created initially as an in-memory table but becomes too large, MySQL automatically converts it to an on-disk table. The maximum size for in-memory temporary tables is the minimum of the tmp_table_size and max_heap_table_size values. If Created_tmp_disk_tables is large, you may want to increase the tmp_table_size or max_heap_table_size values. value to lessen the likelihood that internal temporary tables in memory will be converted to on-disk tables.

  You can compare the number of internal on-disk temporary tables created to the total number of internal temporary tables created by comparing the values of the Created_tmp_disk_tables and Created_tmp_tablesvariables.

  See also Section 8.8.5, “How MySQL Uses Internal Temporary Tables”.

•  Created_tmp_files

  How many temporary files mysqld has created.

•  Created_tmp_tables

  The number of internal temporary tables created by the server while executing statements.

  You can compare the number of internal on-disk temporary tables created to the total number of internal temporary tables created by comparing the values of the Created_tmp_disk_tables and Created_tmp_tablesvariables.

  See also Section 8.8.5, “How MySQL Uses Internal Temporary Tables”.

•  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 times the server flushes tables, whether because a user executed a FLUSH TABLES statement or due to internal server operation. It is also incremented by receipt of a COM_REFRESH packet. This is in contrast toCom_flush, which indicates how many FLUSH statements have been executed, whether FLUSH TABLES, FLUSH LOGS, and so forth.

•  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. Added in MySQL 5.0.3.

•  Handler_read_first

  The number of times the first entry in an index was read. 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 do not 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. Added in MySQL 5.0.3.

•  Handler_savepoint_rollback

  The number of requests for a storage engine to roll back to a savepoint. Added in MySQL 5.0.3.

•  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). Added in MySQL 5.0.2.

•  Innodb_buffer_pool_pages_dirty

  The number of pages currently dirty. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_pages_flushed

  The number of buffer pool page-flush requests. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_pages_free

  The number of free pages. Added in MySQL 5.0.2.

•  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. Added in MySQL 5.0.2. Calculation of this variable is expensive, so as of MySQL 5.0.68, 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. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_pages_total

  The total size of buffer pool, in pages. Added in MySQL 5.0.2.

•  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. Added in MySQL 5.0.2.

•  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. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_read_requests

  The number of logical read requests InnoDB has done. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_reads

  The number of logical reads that InnoDB could not satisfy from the buffer pool, and had to read directly from the disk.

•  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. Added in MySQL 5.0.2.

•  Innodb_buffer_pool_write_requests

  The number writes done to the InnoDB buffer pool. Added in MySQL 5.0.2.

•  Innodb_data_fsyncs

  The number of fsync() operations so far. Added in MySQL 5.0.2.

•  Innodb_data_pending_fsyncs

  The current number of pending fsync() operations. Added in MySQL 5.0.2.

•  Innodb_data_pending_reads

  The current number of pending reads. Added in MySQL 5.0.2.

•  Innodb_data_pending_writes

  The current number of pending writes. Added in MySQL 5.0.2.

•  Innodb_data_read

  The amount of data read since the server was started. Added in MySQL 5.0.2.

•  Innodb_data_reads

  The total number of data reads. Added in MySQL 5.0.2.

•  Innodb_data_writes

  The total number of data writes. Added in MySQL 5.0.2.

•  Innodb_data_written

  The amount of data written so far, in bytes. Added in MySQL 5.0.2.

•  Innodb_dblwr_pages_written

  The number of pages that have been written for doublewrite operations. Added in MySQL 5.0.2. SeeSection 14.2.11.1, “InnoDB Disk I/O”.

•  Innodb_dblwr_writes

  The number of doublewrite operations that have been performed. Added in MySQL 5.0.2. See Section 14.2.11.1, “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. Added in MySQL 5.0.2.

•  Innodb_log_write_requests

  The number of log write requests. Added in MySQL 5.0.2.

•  Innodb_log_writes

  The number of physical writes to the log file. Added in MySQL 5.0.2.

•  Innodb_os_log_fsyncs

  The number of fsync() writes done to the log file. Added in MySQL 5.0.2.

•  Innodb_os_log_pending_fsyncs

  The number of pending log file fsync() operations. Added in MySQL 5.0.2.

•  Innodb_os_log_pending_writes

  The number of pending log file writes. Added in MySQL 5.0.2.

•  Innodb_os_log_written

  The number of bytes written to the log file. Added in MySQL 5.0.2.

•  Innodb_page_size

  The compiled-in InnoDB page size (default 16KB). Many values are counted in pages; the page size permits them to be easily converted to bytes. Added in MySQL 5.0.2.

•  Innodb_pages_created

  The number of pages created. Added in MySQL 5.0.2.

•  Innodb_pages_read

  The number of pages read. Added in MySQL 5.0.2.

•  Innodb_pages_written

  The number of pages written. Added in MySQL 5.0.2.

•  Innodb_row_lock_current_waits

  The number of row locks currently being waited for. Added in MySQL 5.0.3.

•  Innodb_row_lock_time

  The total time spent in acquiring row locks, in milliseconds. Added in MySQL 5.0.3.

•  Innodb_row_lock_time_avg

  The average time to acquire a row lock, in milliseconds. Added in MySQL 5.0.3.

•  Innodb_row_lock_time_max

  The maximum time to acquire a row lock, in milliseconds. Added in MySQL 5.0.3.

•  Innodb_row_lock_waits

  The number of times a row lock had to be waited for. Added in MySQL 5.0.3.

•  Innodb_rows_deleted

  The number of rows deleted from InnoDB tables. Added in MySQL 5.0.2.

•  Innodb_rows_inserted

  The number of rows inserted into InnoDB tables. Added in MySQL 5.0.2.

•  Innodb_rows_read

  The number of rows read from InnoDB tables. Added in MySQL 5.0.2.

•  Innodb_rows_updated

  The number of rows updated in InnoDB tables. Added in MySQL 5.0.2.

•  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 5.1.4, “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. This variable was added in MySQL 5.0.1, with a default value of -1. In MySQL 5.0.7, the default was changed to 0; also in version 5.0.7, the scope of Last_query_cost was changed to session rather than global.

  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.

  Prior to MySQL 5.0.16, this variable was not updated for queries served from the query cache.

•  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 DELAYED 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_tables

  The number of tables that are open.

•  Opened_tables

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

•  Prepared_stmt_count

  The current number of prepared statements. (The maximum number of statements is given by themax_prepared_stmt_count system variable.) This variable was added in MySQL 5.0.32.

•  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 noncached 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. It does not count COM_PING or COM_STATISTICS commands. This variable was added in MySQL 5.0.76.

•  Questions

  The number of statements executed by the server. As of MySQL 5.0.72, this includes only statements sent to the server by clients and no longer includes statements executed within stored programs, unlike the Queries variable. This variable does not count COM_PING, COM_STATISTICS, COM_STMT_PREPARE, COM_STMT_CLOSE, orCOM_STMT_RESET commands.

•  Rpl_status

  The status of fail-safe replication (not implemented). This variable is unused and is removed in MySQL 5.6.

•  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. If the value is greater than zero, it is not safe to shut down the slave; see Section 16.4.1.15, “Replication and Temporary Tables”.

•  Slave_retried_transactions

  The total number of times since startup that the replication slave SQL thread has retried transactions. This variable was added in version 5.0.4.

•  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 5.2.4, “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 protocol version of the connection.

•  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.) Added in MySQL 5.0.3.

•  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 forTc_log_max_pages_used. Added in MySQL 5.0.3.

•  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.) Added in MySQL 5.0.3.

•  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 thethread_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 5.0.35. (MySQL Community only)

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User Comments

Posted by Demetrios Stavrinos on July 22 2004 12:27pm[Delete] [Edit]

Reading the explanation for Handler read rnd next , I question it! I list some number from a test db that does almost all accesses by locating a record with a key (GE or xxx%) and then using next to access related record; yet the Handler read rnd next is relatively large.
Handler read key 42053 
Handler read next 453703 
Handler read rnd 696 
Handler read rnd next 104378 

Posted by Heikki Hannikainen on April 28 2006 10:23am[Delete] [Edit]

On MySQL 5.0 the com_* variables of 'show status' are counted for the current connection only. The new undocumented command 'show global status' shows server-wide counters. (http://bugs.mysql.com/bug.php?id=19422)

Posted by sheila yao on April 16 2007 9:23pm[Delete] [Edit]

In version 4.0.17, the explanation to Handler_ is different:
Example:
Handler_delete:
The number of times a row was deleted from a table.
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.

Could this be a typo for Handler_delete? Because requests and rows updated/deleted/inserted are different concept.

Sheila

Posted by Roel Van de Paar on September 21 2009 4:34am[Delete] [Edit]

There's a bug in 5.0.36 (and likely surrounding versions) for Handler_write: it increases by one every time a row from SHOW STATUS is displayed:

------
mysql> FLUSH STATUS;
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW GLOBAL STATUS; SHOW SESSION STATUS;
[...] 224 rows in set (0.01 sec)
[...] 224 rows in set (0.01 sec)

mysql> SHOW SESSION STATUS LIKE 'Handler_write';

+---------------+-------+| Variable_name | Value |+---------------+-------+| Handler_write | 448   | +---------------+-------+

1 row in set (0.00 sec)
------

Given the bug for Handler_write it is not possible to find out how many rows were inserted in this version, unless you use a workaround:

Rows_inserted= Handler_write - (number of times SHOW STATUS was run * number of rows SHOW STATUS displayed)

This could be programmed further using the Com_show_status variable:

--------
mysql> SHOW SESSION STATUS LIKE 'Com_show_status';

+-----------------+-------+| Variable_name   | Value |+-----------------+-------+| Com_show_status | 8     | +-----------------+-------+

1 row in set (0.00 sec)
--------

So, on a system/version that had 224 rows in SHOW STATUS (please check), the workaround formula would be:

Rows_inserted=Handler_write-(Com_show_status * 224)

Note though that this workaround does not work when using partial SHOW STATUS statements (using LIKE etc) from time to time.

转自 http://dev.mysql.com/doc/refman/5.0/en/server-status-variables.html#statvar_Queries