SHOW Syntax
SHOW
has many forms that provide information about
databases, tables, columns, or status information about the server. This
section describes those following:
1 | SHOW {BINARY | MASTER} LOGS |
If the syntax for a given SHOW
statement includes a
LIKE '*
pattern*'
part,
'*
pattern*'
is a string that can contain the
SQL %
and _
wildcard characters. The pattern
is useful for restricting statement output to matching values.
Several SHOW
statements also accept a WHERE
clause that provides more flexibility in specifying which rows to
display.
In addition, you can work in SQL with results from queries on tables
in the INFORMATION_SCHEMA
database, which you cannot easily
do with results from SHOW
statements.
SHOW STATUS Syntax
1 | SHOW [GLOBAL | SESSION] STATUS |
SHOW STATUS
provides server status information. This
statement does not require any privilege. It requires only the ability
to connect to the server.
Status variable information is also available from these sources:
- Performance Schema tables.
- The mysqladmin extended-status command.
For SHOW STATUS
, a LIKE
clause, if present,
indicates which variable names to match. A WHERE
clause can
be given to select rows using more general conditions.
SHOW STATUS
accepts an optional GLOBAL
or
SESSION
variable scope modifier:
- With a
GLOBAL
modifier, the statement displays the global status values. A global status variable may represent status for some aspect of the server itself (for example,Aborted_connects
), or the aggregated status over all connections to MySQL (for example,Bytes_received
andBytes_sent
). If a variable has no global value, the session value is displayed. - With a
SESSION
modifier, the statement displays the status variable values for the current connection. If a variable has no session value, the global value is displayed.LOCAL
is a synonym forSESSION
. - If no modifier is present, the default is
SESSION
.
Each invocation of the SHOW STATUS
statement uses an
internal temporary table and increments the
globalCreated_tmp_tables
value.
Partial output is shown here. The list of names and values may differ for your server.
1 | mysql> SHOW STATUS; |
With a LIKE
clause, the statement displays only rows for
those variables with names that match the pattern:
1 | mysql> SHOW STATUS LIKE 'Key%'; |
Performance Schema Status Variable Tables
The MySQL server maintains many status variables that provide information about its operation. Status variable information is available in these Performance Schema tables:
global_status
: Global status variables. An application that wants only global values should use this table.session_status
: Status variables for the current session. An application that wants all status variable values for its own session should use this table. It includes the session variables for its session, as well as the values of global variables that have no session counterpart.status_by_thread
: Session status variables for each active session. An application that wants to know the session variable values for specific sessions should use this table. It includes session variables only, identified by thread ID.
There are also summary tables that provide status variable information aggregated by account, host name, and user name.
The session variable tables (session_status
,
status_by_thread
) contain information only for active
sessions, not terminated sessions.
The Performance Schema collects statistics for global status
variables only for threads for which the INSTRUMENTED
value
is YES
in the threads
table. Statistics for
session status variables are always collected, regardless of the
INSTRUMENTED
value.
The Performance Schema does not collect statistics for
Com_*
xxx*
status variables in the status
variable tables. To obtain global and per-session statement execution
counts, use
theevents_statements_summary_global_by_event_name
andevents_statements_summary_by_thread_by_event_name
tables, respectively. For example:
1 | SELECT EVENT_NAME, COUNT_STAR |
The global_status
and session_status
tables
have these columns:
VARIABLE_NAME
The status variable name.
VARIABLE_VALUE
The status variable value. For
global_status
, this column contains the global value. Forsession_status
, this column contains the variable value for the current session.
The global_status
and session_status
tables
have these indexes:
- Primary key on (
VARIABLE_NAME
)
The status_by_thread
table contains the status of each
active thread. It has these columns:
THREAD_ID
The thread identifier of the session in which the status variable is defined.
VARIABLE_NAME
The status variable name.
VARIABLE_VALUE
The session variable value for the session named by the
THREAD_ID
column.
The status_by_thread
table has these indexes:
- Primary key on (
THREAD_ID
,VARIABLE_NAME
)
The status_by_thread
table contains status variable
information only about foreground threads. If
theperformance_schema_max_thread_instances
system variable
is not autoscaled (signified by a value of −1) and the maximum permitted
number of instrumented thread objects is not greater than the number of
background threads, the table will be empty.
The Performance Schema supports TRUNCATE TABLE
for
status variable tables as follows:
global_status
: Resets thread, account, host, and user status. Resets global status variables except those that the server never resets.session_status
: Not supported.status_by_thread
: Aggregates status for all threads to the global status and account status, then resets thread status. If account statistics are not collected, the session status is added to host and user status, if host and user status are collected.Account, host, and user statistics are not collected if the
performance_schema_accounts_size
,performance_schema_hosts_size
, andperformance_schema_users_size
system variables, respectively, are set to 0.
FLUSH STATUS
adds the session status from all active
sessions to the global status variables, resets the status of all active
sessions, and resets account, host, and user status values aggregated
from disconnected sessions.
Server Status Variables
The MySQL 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. The optional GLOBAL
keyword aggregates the
values over all connections, and SESSION
shows the values
for the current connection.
1 | mysql> SHOW GLOBAL STATUS; |
Many status variables are reset to 0 by the FLUSH STATUS
statement.
This section provides a description of each status variable. For a status variable summary.
The status variables have the following meanings.
Aborted_clients
The number of connections that were aborted because the client died without closing the connection properly.
Aborted_connects
The number of failed attempts to connect to the MySQL server.
For additional connection-related information, check the
Connection_errors_*
xxx*
status variables and thehost_cache
table.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.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.Acl_cache_items_count
The number of cached privilege objects. Each object is the privilege combination of a user and its active roles.
Binlog_cache_use
The number of transactions that used the binary log cache.
Binlog_stmt_cache_disk_use
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.Binlog_stmt_cache_use
The number of nontransactional statements that used the binary log statement cache.
Bytes_received
The number of bytes received from all clients.
Bytes_sent
The number of bytes sent to all clients.
Caching_sha2_password_rsa_public_key
The public key used by the
caching_sha2_password
authentication plugin for RSA key pair-based password exchange. The value is nonempty only if the server successfully initializes the private and public keys in the files named by thecaching_sha2_password_private_key_path
andcaching_sha2_password_public_key_path
system variables. The value ofCaching_sha2_password_rsa_public_key
comes from the latter file.Com_*
xxx*
The
Com_*
xxx*
statement counter variables indicate the number of times eachxxx
statement has been executed. There is one status variable for each type of statement. For example,Com_delete
andCom_update
countDELETE
andUPDATE
statements, respectively.Com_delete_multi
andCom_update_multi
are similar but apply toDELETE
andUPDATE
statements that use multiple-table syntax.The discussion at the beginning of this section indicates how to relate these statement-counting status variables to other such variables.
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 asmysql_stmt_prepare(), mysql_stmt_execute(), and so forth are executed. However,Com_stmt_prepare
,Com_stmt_execute
andCom_stmt_close
also increase forPREPARE
,EXECUTE
, orDEALLOCATE PREPARE
, respectively. Additionally, the values of the older statement counter variablesCom_prepare_sql
,Com_execute_sql
, andCom_dealloc_sql
increase for thePREPARE
,EXECUTE
, andDEALLOCATE 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, for example, after metadata changes to tables or views referred to by the statement. A reprepare operation incrementsCom_stmt_reprepare
, and alsoCom_stmt_prepare
.Com_explain_other
indicates the number ofEXPLAIN FOR CONNECTION
statements executed.Com_change_repl_filter
indicates the number ofCHANGE REPLICATION FILTER
statements executed.Compression
Whether the client connection uses compression in the client/server protocol.
As of MySQL 8.0.18, this status variable is deprecated. It will be removed in a future MySQL version. See Legacy Connection Compression Configuration.
Compression_algorithm
The name of the compression algorithm in use for the current connection to the server. The value can be any algorithm permitted in the value of the
protocol_compression_algorithms
system variable. For example, the value isuncompressed
if the connection does not use compression, orzlib
if the connection uses thezlib
algorithm.This variable was added in MySQL 8.0.18.
Compression_level
The compression level in use for the current connection to the server. The value is 6 for
zlib
connections (the defaultzlib
algorithm compression level), 1 to 22 forzstd
connections, and 0 foruncompressed
connections.This variable was added in MySQL 8.0.18.
Connection_errors_*
xxx*
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, 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).
Connection_errors_accept
The number of errors that occurred during calls to
accept()
on the listening port.Connection_errors_internal
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.Connection_errors_peer_address
The number of errors that occurred while searching for connecting client IP addresses.
Connection_errors_select
The number of errors that occurred during calls to
select()
orpoll()
on the listening port. (Failure of this operation does not necessarily means a client connection was rejected.)Connection_errors_tcpwrap
The number of connections refused by the
libwrap
library.
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
andmax_heap_table_size
values. IfCreated_tmp_disk_tables
is large, you may want to increase thetmp_table_size
ormax_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
andCreated_tmp_tables
variables.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
andCreated_tmp_tables
variables.Each invocation of the
SHOW STATUS
statement uses an internal temporary table and increments the globalCreated_tmp_tables
value.Current_tls_ca
The active
ssl_ca
value in the SSL context that the server uses for new connections. This context value may differ from the currentssl_ca
system variable value if the system variable has been changed butALTER INSTANCE RELOAD TLS
has not subsequently been executed to reconfigure the SSL context from the context-related system variable values and update the corresponding status variables. (This potential difference in values applies to each corresponding pair of context-related system and status variables.This variable was added in MySQL 8.0.16.
Current_tls_capath
The active
ssl_capath
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_cert
The active
ssl_cert
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_cipher
The active
ssl_cipher
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_ciphersuites
The active
tls_ciphersuites
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_crl
The active
ssl_crl
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_crlpath
The active
ssl_crlpath
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_key
The active
ssl_key
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Current_tls_version
The active
tls_version
value in the SSL context that the server uses for new connections. For notes about the relationship between this status variable and its corresponding system variable, see the description ofCurrent_tls_ca
.This variable was added in MySQL 8.0.16.
Delayed_errors
This status variable is deprecated (because
DELAYED
inserts are not supported), and will be removed in a future release.Delayed_insert_threads
This status variable is deprecated (because
DELAYED
inserts are not supported), and will be removed in a future release.Delayed_writes
This status variable is deprecated (because
DELAYED
inserts are not supported), and will be removed in a future release.dragnet.Status
The result of the most recent assignment to the
dragnet.log_error_filter_rules
system variable, empty if no such assignment has occurred.This variable was added in MySQL 8.0.12.
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 aCOM_REFRESH
packet. This is in contrast toCom_flush
, which indicates how manyFLUSH
statements have been executed, whetherFLUSH TABLES
,FLUSH LOGS
, and so forth.group_replication_primary_member
Shows the primary member's UUID when the group is operating in single-primary mode. If the group is operating in multi-primary mode, shows an empty string.
The
group_replication_primary_member
status variable has been deprecated and is scheduled to be removed in a future version.Handler_commit
The number of internal
COMMIT
statements.Handler_delete
The number of times that rows have been deleted from tables.
Handler_external_lock
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.Handler_mrr_init
The number of times the server uses a storage engine's own Multi-Range Read implementation for table access.
Handler_prepare
A counter for the prepare phase of two-phase commit operations.
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 thatcol1
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_last
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 withORDER BY DESC
, the server will issue a last-key request followed by several previous-key requests.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.
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_available_undo_logs
Innodb_available_undo_logs
was removed in MySQL 8.0.2. The number of available rollback segments per tablespace may be retrieved usingSHOW VARIABLES LIKE 'innodb_rollback_segments';
Innodb_buffer_pool_dump_status
The progress of an operation to record the pages held in the
InnoDB
buffer pool, triggered by the setting ofinnodb_buffer_pool_dump_at_shutdown
orinnodb_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 ofinnodb_buffer_pool_load_at_startup
orinnodb_buffer_pool_load_now
. If the operation introduces too much overhead, you can cancel it by settinginnodb_buffer_pool_load_abort
.Innodb_buffer_pool_bytes_data
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 withInnodb_buffer_pool_pages_data
, when compressed tables cause the buffer pool to hold pages of different sizes.Innodb_buffer_pool_pages_data
The number of pages in the
InnoDB
buffer pool containing data. The number includes both dirty and clean pages. When using compressed tables, the reportedInnodb_buffer_pool_pages_data
value may be larger thanInnodb_buffer_pool_pages_total
(Bug #59550).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 withInnodb_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.Innodb_buffer_pool_pages_free
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 theUNIV_DEBUG
system is defined at server build time.Innodb_buffer_pool_pages_misc
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 asInnodb_buffer_pool_pages_total
−Innodb_buffer_pool_pages_free
−Innodb_buffer_pool_pages_data
. When using compressed tables,Innodb_buffer_pool_pages_misc
may report an out-of-bounds value (Bug #59550).Innodb_buffer_pool_pages_total
The total size of the
InnoDB
buffer pool, in pages. When using compressed tables, the reportedInnodb_buffer_pool_pages_data
value may be larger thanInnodb_buffer_pool_pages_total
(Bug #59550)Innodb_buffer_pool_read_ahead
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_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_requests
The number of logical read requests.
Innodb_buffer_pool_reads
The number of logical reads that
InnoDB
could not satisfy from the buffer pool, and had to read directly from disk.Innodb_buffer_pool_resize_status
The status of an operation to resize the
InnoDB
buffer pool dynamically, triggered by setting theinnodb_buffer_pool_size
parameter dynamically. Theinnodb_buffer_pool_size
parameter is dynamic, which allows you to resize the buffer pool without restarting the server. See Configuring InnoDB Buffer Pool Size Online for related information.Innodb_buffer_pool_wait_free
Normally, writes to the
InnoDB
buffer pool happen in the background. WhenInnoDB
needs to read or create a pageand 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. Ifinnodb_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.Innodb_data_fsyncs
The number of
fsync()
operations so far. The frequency offsync()
calls is influenced by the setting of theinnodb_flush_method
configuration option.Innodb_data_pending_fsyncs
The current number of pending
fsync()
operations. The frequency offsync()
calls is influenced by the setting of theinnodb_flush_method
configuration option.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 since the server was started (in bytes).
Innodb_data_reads
The total number of data reads (OS file 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 to the doublewrite buffer.
Innodb_dblwr_writes
The number of doublewrite operations that have been performed.
Innodb_have_atomic_builtins
Indicates whether the server was built with atomic instructions.
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 write requests for the
InnoDB
redo log.Innodb_log_writes
The number of physical writes to the
InnoDB
redo log file.Innodb_num_open_files
The number of files
InnoDB
currently holds open.Innodb_os_log_fsyncs
The number of
fsync()
writes done to theInnoDB
redo log files.Innodb_os_log_pending_fsyncs
The number of pending
fsync()
operations for theInnoDB
redo log files.Innodb_os_log_pending_writes
The number of pending writes to the
InnoDB
redo log files.Innodb_os_log_written
The number of bytes written to the
InnoDB
redo log files.Innodb_page_size
InnoDB
page size (default 16KB). Many values are counted in pages; the page size enables them to be easily converted to bytes.Innodb_pages_created
The number of pages created by operations on
InnoDB
tables.Innodb_pages_read
The number of pages read from the
InnoDB
buffer pool by operations onInnoDB
tables.Innodb_pages_written
The number of pages written by operations on
InnoDB
tables.Innodb_row_lock_current_waits
The number of row locks currently being waited for by operations on
InnoDB
tables.Innodb_row_lock_time
The total time spent in acquiring row locks for
InnoDB
tables, in milliseconds.Innodb_row_lock_time_avg
The average time to acquire a row lock for
InnoDB
tables, in milliseconds.Innodb_row_lock_time_max
The maximum time to acquire a row lock for
InnoDB
tables, in milliseconds.Innodb_row_lock_waits
The number of times operations on
InnoDB
tables had to wait for a row lock.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.Innodb_truncated_status_writes
The number of times output from the
SHOW ENGINE INNODB STATUS
statement has been truncated.Key_blocks_not_flushed
The number of key blocks in the
MyISAM
key cache that have changed but have not yet been flushed to disk.Key_blocks_unused
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 ofkey_buffer_size
in Section “Server System Variables”.Key_blocks_used
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.Key_read_requests
The number of requests to read a key block from the
MyISAM
key cache.Key_reads
The number of physical reads of a key block from disk into the
MyISAM
key cache. IfKey_reads
is large, then yourkey_buffer_size
value is probably too small. The cache miss rate can be calculated asKey_reads
/Key_read_requests
.Key_write_requests
The number of requests to write a key block to the
MyISAM
key cache.Key_writes
The number of physical writes of a key block from the
MyISAM
key cache 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.In MySQL 8.0.16 and later, this variable shows the cost of queries that have multiple query blocks, summing the cost estimates of each query block, estimating how many times non-cacheable subqueries are executed, and multiplying the cost of those query blocks by the number of subquery executions. (Bug #92766, Bug #28786951) Prior to MySQL 8.0.16,
Last_query_cost
was computed accurately only for simple, “flat” queries, but not for complex queries such as those containing subqueries orUNION
. (For the latter, the value was set to 0.)Last_query_partial_plans
The number of iterations the query optimizer made in execution plan construction for the previous query.
Last_query_cost
has session scope.Locked_connects
The number of attempts to connect to locked user accounts. For information about account locking and unlocking.
Max_execution_time_exceeded
The number of
SELECT
statements for which the execution timeout was exceeded.Max_execution_time_set
The number of
SELECT
statements for which a nonzero execution timeout was set. This includes statements that include a nonzeroMAX_EXECUTION_TIME
optimizer hint, and statements that include no such hint but execute while the timeout indicated by themax_execution_time
system variable is nonzero.Max_execution_time_set_failed
The number of
SELECT
statements for which the attempt to set an execution timeout failed.Max_used_connections
The maximum number of connections that have been in use simultaneously since the server started.
Max_used_connections_time
The time at which
Max_used_connections
reached its current value.Not_flushed_delayed_rows
This status variable is deprecated (because
DELAYED
inserts are not supported), and will be removed in a future release.mecab_charset
The character set currently used by the MeCab full-text parser plugin.
Ongoing_anonymous_transaction_count
Shows the number of ongoing transactions which have been marked as anonymous. This can be used to ensure that no further transactions are waiting to be processed.
Ongoing_anonymous_gtid_violating_transaction_count
This status variable is only available in debug builds. Shows the number of ongoing transactions which use
gtid_next=ANONYMOUS
and that violate GTID consistency.Ongoing_automatic_gtid_violating_transaction_count
This status variable is only available in debug builds. Shows the number of ongoing transactions which use
gtid_next=AUTOMATIC
and that violate GTID consistency.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 table definitions.
Open_tables
The number of tables that are open.
Opened_files
The number of files that have been opened with
my_open()
(amysys
library function). Parts of the server that open files without using this function do not increment the count.Opened_table_definitions
The number of table definitions that have been cached.
Opened_tables
The number of tables that have been opened. If
Opened_tables
is big, yourtable_open_cache
value is probably too small.Performance_schema_*
xxx*
Performance Schema status variables are listed in Section “Performance Schema Status Variables”. These variables provide information about instrumentation that could not be loaded or created due to memory constraints.
Prepared_stmt_count
The current number of prepared statements. (The maximum number of statements is given by the
max_prepared_stmt_count
system variable.)Qcache_free_blocks
This status variable was removed in MySQL 8.0.3.
Qcache_free_memory
This status variable was removed in MySQL 8.0.3.
Qcache_hits
This status variable was removed in MySQL 8.0.3.
Qcache_inserts
This status variable was removed in MySQL 8.0.3.
Qcache_lowmem_prunes
This status variable was removed in MySQL 8.0.3.
Qcache_not_cached
This status variable was removed in MySQL 8.0.3.
Qcache_queries_in_cache
This status variable was removed in MySQL 8.0.3.
Qcache_total_blocks
This status variable was removed in MySQL 8.0.3.
Queries
The number of statements executed by the server. This variable includes statements executed within stored programs, unlike the
Questions
variable. It does not countCOM_PING
orCOM_STATISTICS
commands.The discussion at the beginning of this section indicates how to relate this statement-counting status variable to other such variables.
Questions
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 countCOM_PING
,COM_STATISTICS
,COM_STMT_PREPARE
,COM_STMT_CLOSE
, orCOM_STMT_RESET
commands.The discussion at the beginning of this section indicates how to relate this statement-counting status variable to other such variables.
Rpl_semi_sync_master_clients
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 always
0
, is deprecated and it will be removed in a future version.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 always
0
, is deprecated and it will be removed in a future version.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.
Rpl_semi_sync_master_no_times
The number of times the master turned off semisynchronous replication.
This variable is available only if the master-side semisynchronous replication plugin is installed.
Rpl_semi_sync_master_no_tx
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.
Rpl_semi_sync_master_status
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 isOFF
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.
Rpl_semi_sync_master_tx_waits
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.
Rpl_semi_sync_master_yes_tx
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.
Rpl_semi_sync_slave_status
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.
Rsa_public_key
The value of this variable is the public key used by the
sha256_password
authentication plugin for RSA key pair-based password exchange. The value is nonempty only if the server successfully initializes the private and public keys in the files named by thesha256_password_private_key_path
andsha256_password_public_key_path
system variables. The value ofRsa_public_key
comes from the latter file.Secondary_engine_execution_count
For future use. This variable was added in MySQL 8.0.13.
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_heartbeat_period
This variable is obsolete and was removed in MySQL 8.0.1. Instead, use the
HEARTBEAT_INTERVAL
column of thereplication_connection_configuration
table.Slave_last_heartbeat
This variable is obsolete and was removed in MySQL 8.0.1. Instead, use the
LAST_HEARTBEAT_TIMESTAMP
column of thereplication_connection_status
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; “Replication and Temporary Tables”. This variable reports the total count of open temporary tables for all replication channels.
Slave_received_heartbeats
This variable is obsolete and was removed in MySQL 8.0.1. Instead, use the
COUNT_RECEIVED_HEARTBEATS
column of thereplication_connection_status
table.Slave_retried_transactions
This variable is obsolete and was removed in MySQL 8.0.1. Instead, use the
COUNT_TRANSACTIONS_RETRIES
column of thereplication_applier_status
table.Slave_rows_last_search_algorithm_used
The search algorithm that was most recently used by this slave to locate rows for row-based replication. The result shows whether the slave used indexes, a table scan, or hashing as the search algorithm for the last transaction executed on any channel.
The method used depends on the setting for the
slave_rows_search_algorithms
system variable, and the keys that are available on the relevant table.This variable is available only for debug builds of MySQL.
Slave_running
This variable is obsolete and was removed in MySQL 8.0.1. Instead, use the
SERVICE_STATE
column of thereplication_connection_status
andreplication_applier_status
tables.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. This counter increments regardless of whether the slow query log is enabled.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 encryption cipher (empty for unencrypted connections).
Ssl_cipher_list
The list of possible SSL ciphers (empty for non-SSL connections). If MySQL supports TLSv1.3, the value includes the possible TLSv1.3 ciphersuites.
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_server_not_after
The last date for which the SSL certificate is valid. To check SSL certificate expiration information, use this statement:
1
2
3
4
5
6
7mysql> SHOW STATUS LIKE 'Ssl_server_not%';
+-----------------------+--------------------------+
| Variable_name | Value |
+-----------------------+--------------------------+
| Ssl_server_not_after | Apr 28 14:16:39 2025 GMT |
| Ssl_server_not_before | May 1 14:16:39 2015 GMT |
+-----------------------+--------------------------+Ssl_server_not_before
The first date for which the SSL certificate is valid.
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 used by the server for a connection that uses SSL. The value is a bitmask; bits are defined in the
openssl/ssl.h
header file:1
2
3
4define SSL_VERIFY_NONE 0x00
define SSL_VERIFY_PEER 0x01
define SSL_VERIFY_FAIL_IF_NO_PEER_CERT 0x02
define SSL_VERIFY_CLIENT_ONCE 0x04SSL_VERIFY_PEER
indicates that the server asks for a client certificate. If the client supplies one, the server performs verification and proceeds only if verification is successful.SSL_VERIFY_CLIENT_ONCE
indicates that a request for the client certificate will be done only in the initial handshake.Ssl_version
The SSL protocol version of the connection (for example, TLSv1). If the connection is not encrypted, the value is empty.
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.
Table_open_cache_hits
The number of hits for open tables cache lookups.
Table_open_cache_misses
The number of misses for open tables cache lookups.
Table_open_cache_overflows
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
.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
andTc_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. 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 that are capable of two-phase commit and that support XA transactions 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()
. This variable is unused for the same reasons as described forTc_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 thethread_cache_size
value. The cache miss rate can be calculated asThreads_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.