In MySQL, show status introduces a

Company products to MySQL cluster, cluster encountered problems, need to look at the cluster status, use the command show status, today took the opportunity to show the status of the various variables of the meaning of the study.

Status name	Scope	Detailed explanation
Aborted_clients	Global	The number of connections that were interrupted due to client termination because the client did not close the connection properly
Aborted_connects	Global	The number of connections that failed while attempting to connect to the MySQL server
Binlog_cache_disk_use	Global	The number of transactions that use the temporary binary log cache but exceed the Binlog_cache_size value and use temporary files to hold statements in the transaction
Binlog_cache_use	Global	Number of transactions using the staging binary log cache
Bytes_received	Both	The number of bytes received from all clients.
Bytes_sent	Both	The number of bytes sent to all clients.
com*		The number of various database operations
Compression	Session	No compression protocol enabled between client and server
Connections	Global	The number of connections to the MySQL server that you are trying to connect to (regardless of success)
Created_tmp_disk_tables	Both	The number of temporary tables that are automatically created on the hard disk when the server executes the statement
Created_tmp_files	Global	Mysqld the number of temporary files that have been created
Created_tmp_tables	Both	The number of temporary tables in memory that are automatically created when the server executes the statement. If the created_tmp_disk_tables is larger, you may want to increase the tmp_table_size value to make the temp table memory-based and not disk-based
Delayed_errors	Global	The number of rows in the error that were written with the insert delayed (possibly duplicate key).
Delayed_insert_threads	Global	The number of insert delayed processor threads used.
Delayed_writes	Global	Number of insert delayed lines written
Flush_commands	Global	The number of flush statements executed.
Handler_commit	Both	Number of internal commit statements
Handler_delete	Both	The number of times the row was deleted from the table.
Handler_discover	Both	The MySQL server can ask NDB cluster if the storage engine knows the table of a certain name. This is called discovery. Handler_discover describes the number of times that this method was discovered.
Handler_prepare	Both	A counter for the prepare phase of two-phase commit operations.
Handler_read_first	Both	The number of times the first bar in the index was read. If it is high, it is recommended that the server is performing a large number of full-index scans; for example, SELECT col1 from Foo, assuming col1 has an index.
Handler_read_key	Both	The number of requests to read a row by key. If it is high, the index of the query and table is correct.
Handler_read_next	Both	Reads the number of requests for the next line in key order. This value increases if you query an index column with a range constraint or if an index scan is performed.
Handler_read_prev	Both	The number of requests to read the previous line in the key order. This reading method is mainly used to optimize the order by ... DESC.
Handler_read_rnd	Both	The number of requests to read a row based on a fixed location. This value is higher if you are executing a large number of queries and need to sort the results. You may have used a large number of queries that require MySQL to scan the entire table or your connection did not use the keys correctly.
Handler_read_rnd_next	Both	The number of requests to read the next line in the data file. If you are doing a large number of table scans, this value is higher. It is usually indicated that your table index is incorrect or the query being written does not take advantage of the index.
Handler_rollback	Both	The number of internal rollback statements.
Handler_savepoint	Both	The number of requests to place a savepoint in a storage engine.
Handler_savepoint_rollback	Both	The requirement for a storage engine to roll back to a savepoint number.
Handler_update	Both	The number of requests to update a row within a table.
Handler_write	Both	The number of requests to insert a row within the table.
Innodb_buffer_pool_pages_data	Global	The number of pages that contain data (dirty or clean).
Innodb_buffer_pool_pages_dirty	Global	The current number of dirty pages.
Innodb_buffer_pool_pages_flushed	Global	Number of buffer pool pages required to be emptied
Innodb_buffer_pool_pages_free	Global	Empty pages.
Innodb_buffer_pool_pages_latched	Global	Number of pages locked in the InnoDB buffer pool. This is the number of pages that are currently being read or written or cannot be emptied or deleted for other reasons.
Innodb_buffer_pool_pages_misc	Global	The number of pages that are busy, because they have been assigned precedence for administration, such as row locking or applicable hash indexes. The 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	Global	Total buffer pool size (pages).
Innodb_buffer_pool_read_ahead_rnd	Global	InnoDB the number of "random" read-aheads initialized. Occurs when the query scans a large part of a table in a random order.
Innodb_buffer_pool_read_ahead_seq	Global	InnoDB the number of sequential read-aheads initialized. Occurs when InnoDB performs a sequential full-table scan.
Innodb_buffer_pool_read_requests	Global	InnoDB the number of logical read requests that have been completed.
Innodb_buffer_pool_reads	Global	The number of logical reads in the buffer pool that InnoDB must read in a single page cannot be satisfied.
Innodb_buffer_pool_wait_free	Global	In general, write to the InnoDB buffer pool through the background. However, if you need to read or create a page, and there is no clean page available, it also needs to wait for the page to empty first. The counter counts the waiting instance. If the buffer pool size is already set appropriately, the value should be small.
Innodb_buffer_pool_write_requests	Global	The number of writes to the InnoDB buffer pool.
Innodb_data_fsyncs	Global	The number of Fsync () operands.
Innodb_data_pending_fsyncs	Global	The number of Fsync () operands currently pending.
Innodb_data_pending_reads	Global	The current pending reading.
Innodb_data_pending_writes	Global	The current number of pending writes.
Innodb_data_read	Global	The number of data (bytes) that have been read at this point.
Innodb_data_reads	Global	The total number of data reads.
Innodb_data_writes	Global	Total number of data writes.
Innodb_data_written	Global	The amount of data (bytes) that has been written to this point.
Innodb_dblwr_pages_written	Global	Number of double write operations that have been performed
Innodb_dblwr_writes	Global	Number of pages that have been written for double write operations
Innodb_log_waits	Global	We have to wait for the time because the log buffer is too small, we must wait for it to clear before continuing
Innodb_log_write_requests	Global	Number of log write requests.
Innodb_log_writes	Global	The number of physical writes to the log file.
Innodb_os_log_fsyncs	Global	The number of Fsync () writes completed to the log file.
Innodb_os_log_pending_fsyncs	Global	The number of pending log file Fsync () operations.
Innodb_os_log_pending_writes	Global	Pending log File Write operations
Innodb_os_log_written	Global	The number of bytes written to the log file.
Innodb_page_size	Global	The compiled InnoDB page size (default 16KB). Many values are counted in pages, and the size of the page is easily converted to bytes.
innodb_pages_created	Global	Number of pages created.
Innodb_pages_read	Global	The number of pages read.
Innodb_pages_written	Global	Number of pages written.
Innodb_row_lock_current_waits	Global	The number of rows currently waiting to be locked.
Innodb_row_lock_time	Global	The total time, in milliseconds, that the row lock takes.
Innodb_row_lock_time_avg	Global	The average time, in milliseconds, that the row is locked.
Innodb_row_lock_time_max	Global	The maximum time, in milliseconds, that a row is locked.
Innodb_row_lock_waits	Global	The number of times a row lock must wait.
innodb_rows_deleted	Global	The number of rows deleted from the InnoDB table.
innodb_rows_inserted	Global	The number of rows inserted into the InnoDB table.
Innodb_rows_read	Global	The number of rows read from the InnoDB table.
innodb_rows_updated	Global	The number of rows updated in the InnoDB table.
Key_blocks_not_flushed	Global	The number of data blocks in the key cache that have been changed but have not yet been emptied to the hard disk.
Key_blocks_unused	Global	The number of unused blocks in the key cache. You can use this value to determine how many key caches are used
Key_blocks_used	Global	The number of blocks used within the key cache. The value is a high-level line marker that shows how many blocks have been used at the same time.
Key_read_requests	Global	The number of requests from the cache of data blocks that read the key.
Key_reads	Global	The number of times the key's data block was read from the hard disk. If the key_reads is large, the Key_buffer_size value may be too small. You can calculate the cache loss rate with key_reads/key_read_requests.
Key_write_requests	Global	The number of requests to write the key's data block to the cache.
Key_writes	Global	The number of times the physical write operation of the data block to which the key was written to the hard disk.
Last_query_cost	Session	The total cost of the last compiled query computed with the query optimizer. Used to compare the cost of different query scenarios for the same query. The default value of 0 indicates that the query has not been compiled. The default value is 0. Last_query_cost has a session scope.
Max_used_connections	Global	The maximum number of connections that have been used at the same time since the server started.
ndb*		NDB Cluster Related
Not_flushed_delayed_rows	Global	The number of rows waiting to be written to the Insert delay queue.
Open_files	Global	The number of open files.
Open_streams	Global	The number of open streams (primarily for logging).
Open_table_definitions	Global	Number of cached. frm files
Open_tables	Both	The number of tables currently open.
Original address: http://www.sandzhang.com/blog/2010/04/07/mysql-show-status-explained-detail/
Opened_files	Global	The number of open files. Other types of files, such as sockets or pipes, are not included. It does not include files that the storage engine uses to do its own internal functions.
Opened_table_definitions	Both	Number of. frm files that have been cached
Opened_tables	Both	The number of tables that have been opened. If the opened_tables is larger, the Table_cache value may be too small.
Prepared_stmt_count	Global	The number of current preprocessing statements. (Maximum number is System variable: max_prepared_stmt_count)
Qcache_free_blocks	Global	The number of free memory blocks within the query cache.
Qcache_free_memory	Global	The amount of free memory used to query the cache.
Qcache_hits	Global	The number of times the query cache was accessed.
Qcache_inserts	Global	Number of queries added to the cache.
Qcache_lowmem_prunes	Global	The number of queries deleted from the cache because of less memory.
Qcache_not_cached	Global	Number of non-cached queries (not cacheable, or because the Query_cache_type setpoint is not cached).
Qcache_queries_in_cache	Global	The number of queries registered in the cache.
Qcache_total_blocks	Global	The total number of blocks in the query cache.
Queries	Both	The number of requests that the server executes, including requests in the stored procedure.
Questions	Both	The number of queries that have been sent to the server.
Rpl_status	Global	Failed security replication status (not yet used).
Select_full_join	Both	The number of joins that do not use an index. If the value is not 0, you should double-check the index of the table
Select_full_range_join	Both	The number of joins that use a range search in the referenced table.
Select_range	Both	The number of joins that use a range in the first table. The general situation is not a critical issue, even if the value is quite large.
Select_range_check	Both	The number of joins without a key value that are checked for key values after each row of data. If it is not 0, you should carefully check the index of the table.
Select_scan	Both	The number of joins that perform a full scan of the first table.
Slave_heartbeat_period	Global	The heartbeat interval for replication
Slave_open_temp_tables	Global	Number of temporary tables opened from the server
Slave_received_heartbeats	Global	Number of heartbeats from the server
Slave_retried_transactions	Global	Thread attempts to copy lines from the server since this startup
Slave_running	Global	If the server is a slave server that is connected to the primary server, the value is on.
Slow_launch_threads	Both	The number of threads that have been created longer than slow_launch_time seconds.
Slow_queries	Both	The number of queries that have been queried for more than long_query_time seconds.
Sort_merge_passes	Both	The number of merges that the sorting algorithm has performed. If the value of this variable is large, you should consider increasing the value of the sort_buffer_size system variable.
Sort_range	Both	The number of orders performed within the range.
Sort_rows	Both	The number of rows that have been sorted.
Sort_scan	Both	The number of sorting completed by the scan table.
ssl*		SSL connection Related
Table_locks_immediate	Global	The number of times the table's locks are immediately obtained.
table_locks_waited	Global	The number of locks on the table that cannot be obtained immediately. If the value is high and there is a performance problem, you should first refine the query and then split the table or use replication.
Threads_cached	Global	The number of threads within the thread cache.
threads_connected	Global	The number of connections currently open.
threads_created	Global	Creates the number of threads used to process the connection. If the threads_created is larger, you may want to increase the thread_cache_size value. The method of calculating the cache access rate is threads_created/connections.
Threads_running	Global	The number of active (non-sleep-state) threads.
Uptime	Global	The time, in seconds, that the server has been running.
Uptime_since_flush_status	Global	The last time the flush STATUS was used (in seconds)

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In MySQL, show status introduces a