Spec-Zone .ru
спецификации, руководства, описания, API
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Spec-Zone .ru
спецификации, руководства, описания, API
|
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 13.7.5.36,
"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 |+-----------------------------------+------------+
Many status variables are reset to 0 by the FLUSH
STATUS statement.
The following table lists all available server status variables:
Table 5.5. Status Variable Summary
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".
The number of connections that were aborted because the client died without closing the connection properly. See Section C.5.2.11, "Communication Errors and Aborted Connections".
The number of failed attempts to connect to the MySQL server. See Section C.5.2.11, "Communication Errors and Aborted Connections".
For additional connection-related information, check the Connection_errors_
status variables and the xxxhost_cache table.
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.
The number of nontransactional statements that caused the binary log transaction cache to be written
to disk is tracked separately in the Binlog_stmt_cache_disk_use status variable.
The number of transactions that used the binary log cache.
The number of nontransaction statements that used the binary log statement cache but that exceeded
the value of binlog_stmt_cache_size and used a temporary file to store those
statements.
The number of nontransactional statements that used the binary log statement cache.
The number of bytes received from all clients.
The number of bytes sent to all clients.
The Com_ statement counter
variables indicate the number of times each xxxxxx statement
has been executed. There is one status variable for each type of statement. For example, Com_delete and Com_update count DELETE and UPDATE statements, respectively. Com_delete_multi
and Com_update_multi are similar but apply to DELETE and UPDATE statements that use multiple-table syntax.
If a query result is returned from query cache, the server increments the Qcache_hits status variable, not Com_select. See Section
8.9.3.4, "Query Cache Status and Maintenance".
All of the Com_stmt_
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. xxx
The Com_stmt_ status
variables are as follows:xxx
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_ 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, xxxCom_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 PREPARE
statements. Com_stmt_fetch stands for the total number of network
round-trips issued when fetching from cursors.
Com_stmt_reprepare indicates the number of times statements were
automatically reprepared by the server after metadata changes to tables or views referred to by the
statement. A reprepare operation increments Com_stmt_reprepare, and
also Com_stmt_prepare.
Whether the client connection uses compression in the client/server protocol.
These variables provide information about errors that occur during the client connection process. They are global only and represent error counts aggregated across connections from all hosts. These variables track errors not accounted for by the host cache (see Section 8.11.5.2, "DNS Lookup Optimization and the Host Cache"), such as errors that are not associated with TCP connections, occur very early in the connection process (even before an IP address is known), or are not specific to any particular IP address (such as out-of-memory conditions). These variables were added in MySQL 5.6.5.
The number of errors that occurred during calls to accept()
on the listening port.
The number of connections refused due to internal errors in the server, such as failure to start a new thread or an out-of-memory condition.
Connection_errors_max_connections
The number of connections refused because the server max_connections limit was reached.
The number of errors that occurred while searching for connecting client IP addresses.
The number of errors that occurred during calls to select()
or poll() on the listening port. (Failure of this operation
does not necessarily means a client connection was rejected.)
The number of connections refused by the libwrap library.
The number of connection attempts (successful or not) to the MySQL server.
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 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_tables variables.
See also Section 8.4.3.3, "How MySQL Uses Internal Temporary Tables".
How many temporary files mysqld has created.
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_tables variables.
See also Section 8.4.3.3, "How MySQL Uses Internal Temporary Tables".
Each invocation of the SHOW
STATUS statement uses an internal temporary table and increments the global Created_tmp_tables
value.
The number of rows written with INSERT
DELAYED for which some error occurred (probably duplicate
key).
As of MySQL 5.6.7, this status variable is deprecated (because DELAYED
inserts are deprecated), and will be removed in a future release.
The number of INSERT DELAYED
handler threads in use for nontransactional tables.
As of MySQL 5.6.7, this status variable is deprecated (because DELAYED
inserts are deprecated), and will be removed in a future release.
The number of INSERT DELAYED
rows written to nontransactional tables.
As of MySQL 5.6.7, this status variable is deprecated (because DELAYED
inserts are deprecated), and will be removed in a future release.
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 to Com_flush,
which indicates how many FLUSH statements have been executed, whether
FLUSH
TABLES, FLUSH LOGS,
and so forth.
The number of internal COMMIT statements.
The number of times that rows have been deleted from tables.
The server increments this variable for each call to its external_lock() function, which generally occurs at the beginning and end
of access to a table instance. There might be differences among storage engines. This variable can
be used, for example, to discover for a statement that accesses a partitioned table how many
partitions were pruned before locking occurred: Check how much the counter increased for the
statement, subtract 2 (2 calls for the table itself), then divide by 2 to get the number of
partitions locked. This variable was added in MySQL 5.6.2.
The number of times the server uses a storage engine's own Multi-Range Read implementation for table access. This variable was added in MySQL 5.6.1.
A counter for the prepare phase of two-phase commit operations.
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.
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.
The number of requests to read the last key in an index. With ORDER BY,
the server will issue a first-key request followed by several next-key requests, whereas with With
ORDER BY DESC, the server will issue a last-key request followed by
several previous-key requests. This variable was added in MySQL 5.6.1.
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.
The number of requests to read the previous row in key order. This read method is mainly used to
optimize ORDER BY ... DESC.
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.
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.
The number of requests for a storage engine to perform a rollback operation.
The number of requests for a storage engine to place a savepoint.
The number of requests for a storage engine to roll back to a savepoint.
The number of requests to update a row in a table.
The number of requests to insert a row in a table.
The total number of available InnoDB undo logs.
Supplements the innodb_undo_logs system variable, which reports the number of
active undo logs.
Innodb_buffer_pool_dump_status
The progress of an operation to record the pages held in the InnoDB buffer pool, triggered by the setting
of innodb_buffer_pool_dump_at_shutdown or innodb_buffer_pool_dump_now.
Innodb_buffer_pool_load_status
The progress of an operation to warm
up the InnoDB buffer pool by reading in
a set of pages corresponding to an
earlier point in time, triggered by the setting of innodb_buffer_pool_load_at_startup or innodb_buffer_pool_load_now. If the operation introduces too much
overhead, you can cancel it by setting innodb_buffer_pool_load_abort.
The total number of bytes in the InnoDB buffer
pool containing data. The number includes both dirty and clean pages.
For more accurate memory usage calculations than with Innodb_buffer_pool_pages_data, when compressed
tables cause the buffer pool to hold pages of different sizes.
The number of pages in the InnoDB buffer pool containing data. The number
includes both dirty and
clean pages.
Innodb_buffer_pool_bytes_dirty
The total current number of bytes held in dirty pages in the InnoDB buffer pool. For more accurate memory
usage calculations than with Innodb_buffer_pool_pages_dirty, when compressed
tables cause the buffer pool to hold pages of different sizes.
Innodb_buffer_pool_pages_dirty
The current number of dirty
pages in the InnoDB buffer pool.
Innodb_buffer_pool_pages_flushed
The number of requests to flush pages from the InnoDB buffer pool.
The number of free pages in the
InnoDB buffer pool.
Innodb_buffer_pool_pages_latched
The number of latched pages in the
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 it is available only when the UNIV_DEBUG system is defined at server build time.
The number of pages in the InnoDB buffer pool 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 InnoDB buffer pool, in
pages.
The number of pages read into the
InnoDB buffer pool by the read-ahead
background thread.
Innodb_buffer_pool_read_ahead_evicted
The number of pages read into the
InnoDB buffer pool by the read-ahead
background thread that were subsequently evicted without having been
accessed by queries.
Innodb_buffer_pool_read_requests
The number of logical read requests made to the InnoDB buffer
pool. These requests could be serviced by returning data that was already in memory, or by
reading the data from disk into memory first.
The number of logical reads that InnoDB could not satisfy from the buffer pool, and had
to read directly from disk.
Normally, writes to the InnoDB buffer pool
happen in the background. When InnoDB needs to read or create a page and no clean pages are
available, InnoDB flushes some dirty pages
first and waits for that operation to finish. This counter counts instances of these waits. If innodb_buffer_pool_size has been set properly, this value should
be small.
Innodb_buffer_pool_write_requests
The number of writes done to the InnoDB buffer
pool.
The number of fsync() operations so far. The frequency of fsync() calls is influenced by the setting of the innodb_flush_method configuration option.
The current number of pending fsync() operations. The frequency of
fsync() calls is influenced by the setting of the innodb_flush_method configuration option.
The current number of pending reads.
The current number of pending writes.
The amount of data read since the server was started.
The total number of data reads.
The total number of data writes.
The amount of data written so far, in bytes.
The number of pages that have been
written to the doublewrite buffer. See Section
5.3.1, "InnoDB Disk I/O".
The number of doublewrite operations that have been performed. See Section
5.3.1, "InnoDB Disk I/O".
Indicates whether the server was built with atomic instructions.
The number of times that the log buffer was too small and a wait was required for it to be flushed before continuing.
The number of write requests for the InnoDB redo
log.
The number of physical writes to the InnoDB redo
log file.
The number of files InnoDB currently holds open.
The number of fsync() writes done to the InnoDB redo log files.
The number of pending fsync() operations for the InnoDB
redo log files.
The number of pending writes to the InnoDB redo
log files.
The number of bytes written to the InnoDB redo
log files.
The compiled-in InnoDB page size (default 16KB). Many values are
counted in pages; the page size enables them to be easily converted to bytes.
The number of pages created by operations on InnoDB tables.
The number of pages read by operations on InnoDB tables.
The number of pages written by operations on InnoDB tables.
The number of row locks
currently being waited for by operations on InnoDB tables.
The total time spent in acquiring row locks for InnoDB tables, in milliseconds.
The average time to acquire a row
lock for InnoDB tables, in milliseconds.
The maximum time to acquire a row
lock for InnoDB tables, in milliseconds.
The number of times operations on InnoDB tables had to wait for a row lock.
The number of rows deleted from InnoDB tables.
The number of rows inserted into InnoDB tables.
The number of rows read from InnoDB tables.
The number of rows updated in InnoDB tables.
Innodb_truncated_status_writes
The number of times output from the SHOW ENGINE INNODB STATUS statement
has been truncated.
The number of key blocks in the MyISAM key cache that have changed but
have not yet been flushed to disk.
The number of unused blocks in the MyISAM 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".
The number of used blocks in the MyISAM 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.
The number of requests to read a key block from the MyISAM key cache.
The number of physical reads of a key block from disk into the MyISAM
key cache. 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.
The number of requests to write a key block to the MyISAM key cache.
The number of physical writes of a key block from the MyISAM key cache
to disk.
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.
The number of iterations the query optimizer made in execution plan construction for the previous
query. Last_query_cost has session scope. This variable was added in
MySQL 5.6.5.
The maximum number of connections that have been in use simultaneously since the server started.
The number of rows waiting to be written to nontransactional tables in INSERT DELAYED queues.
As of MySQL 5.6.7, this status variable is deprecated (because DELAYED
inserts are deprecated), and will be removed in a future release.
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.
The number of streams that are open (used mainly for logging).
The number of cached .frm files.
The number of tables that are open.
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.
The number of .frm files that have been cached.
The number of tables that have been opened. If Opened_tables is big, your table_open_cache value is probably too small.
Performance_schema_xxx
Performance Schema status variables are listed in Section 21.13, "Performance Schema Status Variables". These variables provide information about instrumentation that could not be loaded or created due to memory constraints.
The current number of prepared statements. (The maximum number of statements is given by the max_prepared_stmt_count system variable.)
The number of free memory blocks in the query cache.
The amount of free memory for the query cache.
The number of query cache hits.
The number of queries added to the query cache.
The number of queries that were deleted from the query cache because of low memory.
The number of noncached queries (not cacheable, or not cached due to the query_cache_type setting).
The number of queries registered in the query cache.
The total number of blocks in the query cache.
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.
The number of statements executed by the server. This includes only statements sent to the server by
clients and not statements executed within stored programs, unlike the Queries variable. This variable does not count COM_PING, COM_STATISTICS, COM_STMT_PREPARE, COM_STMT_CLOSE, or
COM_STMT_RESET commands.
The number of semisynchronous slaves.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_net_avg_wait_time
The average time in microseconds the master waited for a slave reply.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_net_wait_time
The total time in microseconds the master waited for slave replies.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_net_waits
The total number of times the master waited for slave replies.
This variable is available only if the master-side semisynchronous replication plugin is installed.
The number of times the master turned off semisynchronous replication.
This variable is available only if the master-side semisynchronous replication plugin is installed.
The number of commits that were not acknowledged successfully by a slave.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Whether semisynchronous replication currently is operational on the master. The value is ON if the plugin has been enabled and a commit acknowledgment has
occurred. It is OFF if the plugin is not enabled or the master has
fallen back to asynchronous replication due to commit acknowledgment timeout.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_timefunc_failures
The number of times the master failed when calling time functions such as gettimeofday().
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_tx_avg_wait_time
The average time in microseconds the master waited for each transaction.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_tx_wait_time
The total time in microseconds the master waited for transactions.
This variable is available only if the master-side semisynchronous replication plugin is installed.
The total number of times the master waited for transactions.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_wait_pos_backtraverse
The total number of times the master waited for an event with binary coordinates lower than events waited for previously. This can occur when the order in which transactions start waiting for a reply is different from the order in which their binary log events are written.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_wait_sessions
The number of sessions currently waiting for slave replies.
This variable is available only if the master-side semisynchronous replication plugin is installed.
The number of commits that were acknowledged successfully by a slave.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Whether semisynchronous replication currently is operational on the slave. This is ON if the plugin has been enabled and the slave I/O thread is running,
OFF otherwise.
This variable is available only if the slave-side semisynchronous replication plugin is installed.
The RSA public key value used by the sha256_password authentication
plugin. The value is nonempty only if the server successfully initializes the private and public
keys in the files named by the sha256_password_private_key_path and sha256_password_public_key_path system variables. The value of Rsa_public_key
comes from the latter file.
For information about sha256_password, see Section
6.3.7.2, "The SHA-256 Authentication Plugin".
This variable is available only if MySQL was built using OpenSSL. It was added in MySQL 5.6.6.
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.
The number of joins that used a range search on a reference table.
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.
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.
The number of joins that did a full scan of the first table.
Shows the replication heartbeat interval (in seconds) on a replication slave.
Shows when the most recent heartbeat signal was received by a replication slave, as a TIMESTAMP value.
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 16.4.1.22, "Replication and Temporary Tables".
This counter increments with each replication heartbeat received by a replication slave since the
last time that the slave was restarted or reset, or a CHANGE MASTER TO statement was issued.
The total number of times since startup that the replication slave SQL thread has retried transactions.
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.
The number of threads that have taken more than slow_launch_time seconds to create.
The number of queries that have taken more than long_query_time seconds. This counter increments regardless of
whether the slow query log is enabled. For information about that log, see Section
5.2.5, "The Slow Query Log".
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.
The number of sorts that were done using ranges.
The number of sorted rows.
The number of sorts that were done by scanning the table.
The number of negotiates needed to establish the connection.
The number of accepted SSL connections.
The number of callback cache hits.
The current SSL cipher (empty for non-SSL connections).
The list of possible SSL ciphers.
The number of SSL connection attempts to an SSL-enabled master.
The number of negotiates needed to establish the connection to an SSL-enabled master.
The SSL context verification depth (how many certificates in the chain are tested).
The SSL context verification mode.
The default SSL timeout.
The number of successful SSL connections to the server.
The number of successful slave connections to an SSL-enabled master.
The last date for which the SSL certificate is valid. This variable was added in MySQL 5.6.3.
The first date for which the SSL certificate is valid. This variable was added in MySQL 5.6.3.
The number of SSL session cache hits.
The number of SSL session cache misses.
The SSL session cache mode.
The number of SSL session cache overflows.
The SSL session cache size.
The number of SSL session cache timeouts.
How many SSL connections were reused from the cache.
Ssl_used_session_cache_entries
How many SSL session cache entries were used.
The verification depth for replication SSL connections.
The verification mode for replication SSL connections.
The SSL protocol version of the connection.
The number of times that a request for a table lock could be granted immediately.
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.
The number of hits for open tables cache lookups. This variable was added in MySQL 5.6.6.
The number of misses for open tables cache lookups. This variable was added in MySQL 5.6.6.
The number of overflows for the open tables cache. This is the number of times, after a table is
opened or closed, a cache instance has an unused entry and the size of the instance is larger than
table_open_cache
/ table_open_cache_instances. This variable was added in MySQL
5.6.6.
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.)
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.
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.)
The number of threads in the thread cache.
The number of currently open connections.
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.
The number of threads that are not sleeping.
The number of seconds that the server has been up.
The number of seconds since the most recent FLUSH STATUS statement.