Chapter 23 MySQL Performance Schema

Instrumented code is the source for events and produces events to be collected. The setup_instruments table lists the instruments for which events can be collected, whether they are enabled, and (for enabled instruments) whether to collect timing information:

mysql> SELECT * FROM setup_instruments;
+------------------------------------------------------------+---------+-------+
| NAME                                                       | ENABLED | TIMED |
+------------------------------------------------------------+---------+-------+
...
| wait/synch/mutex/sql/LOCK_global_read_lock                 | YES     | YES   |
| wait/synch/mutex/sql/LOCK_global_system_variables          | YES     | YES   |
| wait/synch/mutex/sql/LOCK_lock_db                          | YES     | YES   |
| wait/synch/mutex/sql/LOCK_manager                          | YES     | YES   |
...

The setup_instruments table provides the most basic form of control over event production. To further refine event production based on the type of object or thread being monitored, other tables may be used as described in Section 23.2.3.3, “Event Pre-Filtering”.

Performance Schema tables are the destinations for events and consume events. The setup_consumers table lists the types of consumers to which event information can be sent and whether they are enabled:

mysql> SELECT * FROM setup_consumers;
+----------------------------------+---------+
| NAME                             | ENABLED |
+----------------------------------+---------+
| events_stages_current            | NO      |
| events_stages_history            | NO      |
| events_stages_history_long       | NO      |
| events_statements_current        | YES     |
| events_statements_history        | YES     |
| events_statements_history_long   | NO      |
| events_transactions_current      | NO      |
| events_transactions_history      | NO      |
| events_transactions_history_long | NO      |
| events_waits_current             | NO      |
| events_waits_history             | NO      |
| events_waits_history_long        | NO      |
| global_instrumentation           | YES     |
| thread_instrumentation           | YES     |
| statements_digest                | YES     |
+----------------------------------+---------+

Pre-filtering. This is done by modifying Performance Schema configuration so that only certain types of events are collected from producers, and collected events update only certain consumers. To do this, enable or disable instruments or consumers. Pre-filtering is done by the Performance Schema and has a global effect that applies to all users.

Reasons to use pre-filtering:

Post-filtering. This involves the use of WHERE clauses in queries that select information from Performance Schema tables, to specify which of the available events you want to see. Post-filtering is performed on a per-user basis because individual users select which of the available events are of interest.

Reasons to use post-filtering:

To configure pre-filtering at the producer stage, several tables can be used:

To configure pre-filtering at the consumer stage, modify the setup_consumers table. This determines the destinations to which events are sent. setup_consumers also implicitly affects event production. If a given event will not be sent to any destination (that is, will not be consumed), the Performance Schema does not produce it.

Modifications to some instruments in the setup_instruments table are effective only at server startup; changing them at runtime has no effect. This affects primarily mutexes, conditions, and rwlocks in the server, although there may be other instruments for which this is true. This restriction is lifted as of MySQL 5.7.12.

Modifications to the setup_actors table affect only foreground threads created subsequent to the modification, not existing threads.

What is instrumented is the server code. Changes to this code occur often, which also affects the set of instruments.

It is not practical to list all the instruments because there are hundreds of them.

As described earlier, it is possible to find out by querying the setup_instruments table. This information is always up to date for your version of MySQL, also includes instrumentation for instrumented plugins you might have installed that are not part of the core server, and can be used by automated tools.

HOST

The host name. This should be a literal name, or '%' to mean “any host.”

USER

The user name. This should be a literal name, or '%' to mean “any user.”

ROLE

Unused.

ENABLED

Whether to enable instrumentation for foreground threads matched by the row. The value is YES or NO.

This column was added in MySQL 5.7.6. For earlier versions in which it is not present, the Performance Schema enables instrumentation only for foreground threads matched by some row in the table; instrumentation is implicitly disabled for nonmatching threads.

HISTORY

Whether to log historical events for foreground threads matched by the row. The value is YES or NO.

This column was added in MySQL 5.7.8. For earlier versions in which it is not present, the Performance Schema logs historical events either for all threads or no threads, depending on which history consumers are enabled or disabled.

NAME

The consumer name.

ENABLED

Whether the consumer is enabled. The value is YES or NO. This column can be modified. If you disable a consumer, the server does not spend time adding event information to it.

NAME

The instrument name. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”. Events produced from execution of an instrument have an EVENT_NAME value that is taken from the instrument NAME value. (Events do not really have a “name,” but this provides a way to associate events with instruments.)

ENABLED

Whether the instrument is enabled. The value is YES or NO. This column can be modified. A disabled instrument produces no events.

TIMED

Whether the instrument is timed. This column can be modified.

For memory instruments, the TIMED column in setup_instruments is ignored because memory operations are not timed.

If an enabled instrument is not timed, the instrument code is enabled, but the timer is not. Events produced by the instrument have NULL for the TIMER_START, TIMER_END, and TIMER_WAIT timer values. This in turn causes those values to be ignored when calculating the sum, minimum, maximum, and average time values in summary tables.

OBJECT_TYPE

The type of object to instrument. The value is one of 'EVENT' (Event Scheduler event), 'FUNCTION' (stored function), 'PROCEDURE' (stored procedure), 'TABLE' (base table), or 'TRIGGER' (trigger). Before MySQL 5.7.2, the value is always 'TABLE'.

TABLE filtering affects table I/O events (wait/io/table/sql/handler instrument) and table lock events (wait/lock/table/sql/handler instrument).

OBJECT_SCHEMA

The schema that contains the object. This should be a literal name, or '%' to mean “any schema.”

OBJECT_NAME

The name of the instrumented object. This should be a literal name, or '%' to mean “any object.”

ENABLED

Whether events for the object are instrumented. The value is YES or NO. This column can be modified.

TIMED

Whether events for the object are timed. This column can be modified.

NAME

The type of instrument the timer is used for.

TIMER_NAME

The timer that applies to the instrument type. This column can be modified.

NAME

The instrument name associated with the condition.

OBJECT_INSTANCE_BEGIN

The address in memory of the instrumented condition.

FILE_NAME

The file name.

EVENT_NAME

The instrument name associated with the file.

OPEN_COUNT

The count of open handles on the file. If a file was opened and then closed, it was opened 1 time, but OPEN_COUNT will be 0. To list all the files currently opened by the server, use WHERE OPEN_COUNT > 0.

NAME

The instrument name associated with the mutex.

OBJECT_INSTANCE_BEGIN

The address in memory of the instrumented mutex.

LOCKED_BY_THREAD_ID

When a thread currently has a mutex locked, LOCKED_BY_THREAD_ID is the THREAD_ID of the locking thread, otherwise it is NULL.

The setup_instruments table lists the name of the instrumentation point, with the prefix wait/synch/mutex/.

When some code creates a mutex, a row is added to the mutex_instances table. The OBJECT_INSTANCE_BEGIN column is a property that uniquely identifies the mutex.

When a thread attempts to lock a mutex, the events_waits_current table shows a row for that thread, indicating that it is waiting on a mutex (in the EVENT_NAME column), and indicating which mutex is waited on (in the OBJECT_INSTANCE_BEGIN column).

When a thread succeeds in locking a mutex:

When a thread unlocks a mutex, mutex_instances shows that the mutex now has no owner (the THREAD_ID column is NULL).

When a mutex object is destroyed, the corresponding row is removed from mutex_instances.

events_waits_current, to see what mutex a thread is waiting for

mutex_instances, to see which other thread currently owns a mutex

NAME

The instrument name associated with the lock.

OBJECT_INSTANCE_BEGIN

The address in memory of the instrumented lock.

WRITE_LOCKED_BY_THREAD_ID

When a thread currently has an rwlock locked in exclusive (write) mode, WRITE_LOCKED_BY_THREAD_ID is the THREAD_ID of the locking thread, otherwise it is NULL.

READ_LOCKED_BY_COUNT

When a thread currently has an rwlock locked in shared (read) mode, READ_LOCKED_BY_COUNT is incremented by 1. This is a counter only, so it cannot be used directly to find which thread holds a read lock, but it can be used to see whether there is a read contention on an rwlock, and see how many readers are currently active.

events_waits_current, to see what rwlock a thread is waiting for

rwlock_instances, to see which other thread currently owns an rwlock

EVENT_NAME

The name of the wait/io/socket/* instrument that produced the event. This is a NAME value from the setup_instruments table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”.

OBJECT_INSTANCE_BEGIN

This column uniquely identifies the socket. The value is the address of an object in memory.

THREAD_ID

The internal thread identifier assigned by the server. Each socket is managed by a single thread, so each socket can be mapped to a thread which can be mapped to a server process.

SOCKET_ID

The internal file handle assigned to the socket.

IP

The client IP address. The value may be either an IPv4 or IPv6 address, or blank to indicate a Unix socket file connection.

PORT

The TCP/IP port number, in the range from 0 to 65535.

STATE

The socket status, either IDLE or ACTIVE. Wait times for active sockets are tracked using the corresponding socket instrument. Wait times for idle sockets are tracked using the idle instrument.

A socket is idle if it is waiting for a request from the client. When a socket becomes idle, the event row in socket_instances that is tracking the socket switches from a status of ACTIVE to IDLE. The EVENT_NAME value remains wait/io/socket/*, but timing for the instrument is suspended. Instead, an event is generated in the events_waits_current table with an EVENT_NAME value of idle.

When the next request is received, the idle event terminates, the socket instance switches from IDLE to ACTIVE, and timing of the socket instrument resumes.

For the Unix domain listener socket (server_unix_socket), the port is 0, and the IP is ''.

For client connections via the Unix domain listener (client_connection), the port is 0, and the IP is ''.

For the TCP/IP server listener socket (server_tcpip_socket), the port is always the master port (for example, 3306), and the IP is always 0.0.0.0.

For client connections via the TCP/IP listener (client_connection), the port is whatever the server assigns, but never 0. The IP is the IP of the originating host (127.0.0.1 or ::1 for the local host)

THREAD_ID, EVENT_ID

The thread associated with the event and the thread current event number when the event starts. The THREAD_ID and EVENT_ID values taken together form a primary key that uniquely identifies the row. No two rows will have the same pair of values.

END_EVENT_ID

This column is set to NULL when the event starts and updated to the thread current event number when the event ends.

EVENT_NAME

The name of the instrument that produced the event. This is a NAME value from the setup_instruments table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”.

SOURCE

The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved. For example, if a mutex or lock is being blocked, you can check the context in which this occurs.

TIMER_START, TIMER_END, TIMER_WAIT

Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The TIMER_START and TIMER_END values indicate when event timing started and ended. TIMER_WAIT is the event elapsed time (duration).

If an event has not finished, TIMER_END and TIMER_WAIT are NULL before MySQL 5.7.8. As of 5.7.8, TIMER_END is the current timer value and TIMER_WAIT is the time elapsed so far (TIMER_END − TIMER_START).

If an event is produced from an instrument that has TIMED = NO, timing information is not collected, and TIMER_START, TIMER_END, and TIMER_WAIT are all NULL.

For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 23.2.3.1, “Performance Schema Event Timing”.

SPINS

For a mutex, the number of spin rounds. If the value is NULL, the code does not use spin rounds or spinning is not instrumented.

OBJECT_SCHEMA, OBJECT_NAME, OBJECT_TYPE, OBJECT_INSTANCE_BEGIN

These columns identify the object “being acted on.” What that means depends on the object type.

For a synchronization object (cond, mutex, rwlock):

For a file I/O object:

For a socket object:

For a table I/O object:

An OBJECT_INSTANCE_BEGIN value itself has no meaning, except that different values indicate different objects. OBJECT_INSTANCE_BEGIN can be used for debugging. For example, it can be used with GROUP BY OBJECT_INSTANCE_BEGIN to see whether the load on 1,000 mutexes (that protect, say, 1,000 pages or blocks of data) is spread evenly or just hitting a few bottlenecks. This can help you correlate with other sources of information if you see the same object address in a log file or another debugging or performance tool.

INDEX_NAME

The name of the index used. PRIMARY indicates the table primary index. NULL means that no index was used.

NESTING_EVENT_ID

The EVENT_ID value of the event within which this event is nested.

NESTING_EVENT_TYPE

The nesting event type. The value is TRANSACTION, STATEMENT, STAGE, or WAIT.

OPERATION

The type of operation performed, such as lock, read, or write.

NUMBER_OF_BYTES

The number of bytes read or written by the operation. For table I/O waits (events for the wait/io/table/sql/handler instrument), NUMBER_OF_BYTES is NULL before MySQL 5.7.5. For table I/O events as of 5.7.5, this column indicates the number of rows. If the value is greater than 1, the event is for a batch I/O operation. The following discussion describes the difference between exclusively single-row reporting and reporting that reflects batch I/O.

MySQL executes joins using a nested-loop implementation. The job of the Performance Schema instrumentation is to provide row count and accumulated execution time per table in the join. Assume a join query of the following form that is executed using a table join order of t1, t2, t3:

SELECT ... FROM t1 JOIN t2 ON ... JOIN t3 ON ...

Table “fanout” is the increase or decrease in number of rows from adding a table during join processing. If the fanout for table t3 is greater than 1, the majority of row-fetch operations are for that table. Suppose that the join accesses 10 rows from t1, 20 rows from t2 per row from t1, and 30 rows from t3 per row of table t2. With single-row reporting, the total number of instrumented operations is:

10 + (10 * 20) + (10 * 20 * 30) = 6210

A significant reduction in the number of instrumented operations is achievable by aggregating them per scan (that is, per unique combination of rows from t1 and t2). With batch I/O reporting, the Performance Schema produces an event for each scan of the innermost table t3 rather than for each row, and the number of instrumented row operations reduces to:

10 + (10 * 20) + (10 * 20) = 410

That is a reduction of 93%, illustrating how the batch-reporting strategy significantly reduces Performance Schema overhead for table I/O by reducing the number of reporting calls. The tradeoff is lesser accuracy for event timing. Rather than time for an individual row operation as in per-row reporting, timing for batch I/O includes time spent for operations such as join buffering, aggregation, and returning rows to the client.

For batch I/O reporting to occur, these conditions must be true:

FLAGS

Reserved for future use.

THREAD_ID, EVENT_ID

The thread associated with the event and the thread current event number when the event starts. The THREAD_ID and EVENT_ID values taken together form a primary key that uniquely identifies the row. No two rows will have the same pair of values.

END_EVENT_ID

This column is set to NULL when the event starts and updated to the thread current event number when the event ends.

EVENT_NAME

The name of the instrument that produced the event. This is a NAME value from the setup_instruments table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”.

SOURCE

The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved.

TIMER_START, TIMER_END, TIMER_WAIT

Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The TIMER_START and TIMER_END values indicate when event timing started and ended. TIMER_WAIT is the event elapsed time (duration).

If an event has not finished, TIMER_END and TIMER_WAIT are NULL before MySQL 5.7.8. As of 5.7.8, TIMER_END is the current timer value and TIMER_WAIT is the time elapsed so far (TIMER_END − TIMER_START).

If an event is produced from an instrument that has TIMED = NO, timing information is not collected, and TIMER_START, TIMER_END, and TIMER_WAIT are all NULL.

For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 23.2.3.1, “Performance Schema Event Timing”.

WORK_COMPLETED, WORK_ESTIMATED

These columns provide stage progress information, for instruments that have been implemented to produce such information. WORK_COMPLETED indicates how many work units have been completed for the stage, and WORK_ESTIMATED indicates how many work units are expected for the stage. For more information, see Stage Event Progress Information.

These columns were added in MySQL 5.7.5.

NESTING_EVENT_ID

The EVENT_ID value of the event within which this event is nested. The nesting event for a stage event is usually a statement event.

NESTING_EVENT_TYPE

The nesting event type. The value is TRANSACTION, STATEMENT, STAGE, or WAIT.

THREAD_ID, EVENT_ID

The thread associated with the event and the thread current event number when the event starts. The THREAD_ID and EVENT_ID values taken together form a primary key that uniquely identifies the row. No two rows will have the same pair of values.

END_EVENT_ID

This column is set to NULL when the event starts and updated to the thread current event number when the event ends.

EVENT_NAME

The name of the instrument from which the event was collected. This is a NAME value from the setup_instruments table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”.

For SQL statements, the EVENT_NAME value initially is statement/com/Query until the statement is parsed, then changes to a more appropriate value, as described in Section 23.9.6, “Performance Schema Statement Event Tables”.

SOURCE

The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved.

TIMER_START, TIMER_END, TIMER_WAIT

Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The TIMER_START and TIMER_END values indicate when event timing started and ended. TIMER_WAIT is the event elapsed time (duration).

If an event has not finished, TIMER_END and TIMER_WAIT are NULL before MySQL 5.7.8. As of 5.7.8, TIMER_END is the current timer value and TIMER_WAIT is the time elapsed so far (TIMER_END − TIMER_START).

If an event is produced from an instrument that has TIMED = NO, timing information is not collected, and TIMER_START, TIMER_END, and TIMER_WAIT are all NULL.

For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 23.2.3.1, “Performance Schema Event Timing”.

LOCK_TIME

The time spent waiting for table locks. This value is computed in microseconds but normalized to picoseconds for easier comparison with other Performance Schema timers.

SQL_TEXT

The text of the SQL statement. For a command not associated with an SQL statement, the value is NULL.

As of MySQL 5.7.6, the maximum number of bytes to display can be changed by changing the performance_schema_max_sql_text_length system variable at server startup. Before 5.7.6, the maximum is fixed at 1024.

DIGEST

The statement digest MD5 value as a string of 32 hexadecimal characters, or NULL if the statement_digest consumer is no. For more information about statement digesting, see Section 23.7, “Performance Schema Statement Digests”.

DIGEST_TEXT

The normalized statement digest text, or NULL if the statement_digest consumer is no. For more information about statement digesting, see Section 23.7, “Performance Schema Statement Digests”.

The performance_schema_max_digest_length system variable determines the maximum number of bytes available for computing statement digests. However, the display length of statement digests may be longer than the available buffer size due to encoding of statement components such as keywords and literal values in digest buffer. Consequently, values selected from the DIGEST_TEXT column of statement event tables may appear to exceed the performance_schema_max_digest_length value.

This variable was added in MySQL 5.7.8. In MySQL 5.7.6 and 5.7.7, use max_digest_length instead. Before 5.7.6, the value cannot be changed.

CURRENT_SCHEMA

The default database for the statement, NULL if there is none.

OBJECT_SCHEMA, OBJECT_NAME, OBJECT_TYPE

For nested statements (stored programs), these columns contain information about the parent statement. Otherwise they are NULL.

OBJECT_INSTANCE_BEGIN

This column identifies the statement. The value is the address of an object in memory.

MYSQL_ERRNO

The statement error number, from the statement diagnostics area.

RETURNED_SQLSTATE

The statement SQLSTATE value, from the statement diagnostics area.

MESSAGE_TEXT

The statement error message, from the statement diagnostics area.

ERRORS

Whether an error occurred for the statement. The value is 0 if the SQLSTATE value begins with 00 (completion) or 01 (warning). The value is 1 is the SQLSTATE value is anything else.

WARNINGS

The number of warnings, from the statement diagnostics area.

ROWS_AFFECTED

The number of rows affected by the statement. For a description of the meaning of “affected,” see Section 25.8.7.1, “mysql_affected_rows()”.

ROWS_SENT

The number of rows returned by the statement.

ROWS_EXAMINED

The number of rows read from storage engines during statement execution.

CREATED_TMP_DISK_TABLES

Like the Created_tmp_disk_tables status variable, but specific to the statement.

CREATED_TMP_TABLES

Like the Created_tmp_tables status variable, but specific to the statement.

SELECT_FULL_JOIN

Like the Select_full_join status variable, but specific to the statement.

SELECT_FULL_RANGE_JOIN

Like the Select_full_range_join status variable, but specific to the statement.

SELECT_RANGE

Like the Select_range status variable, but specific to the statement.

SELECT_RANGE_CHECK

Like the Select_range_check status variable, but specific to the statement.

SELECT_SCAN

Like the Select_scan status variable, but specific to the statement.

SORT_MERGE_PASSES

Like the Sort_merge_passes status variable, but specific to the statement.

SORT_RANGE

Like the Sort_range status variable, but specific to the statement.

SORT_ROWS

Like the Sort_rows status variable, but specific to the statement.

SORT_SCAN

Like the Sort_scan status variable, but specific to the statement.

NO_INDEX_USED

1 if the statement performed a table scan without using an index, 0 otherwise.

NO_GOOD_INDEX_USED

1 if the server found no good index to use for the statement, 0 otherwise. For additional information, see the description of the Extra column from EXPLAIN output for the Range checked for each record value in Section 9.8.2, “EXPLAIN Output Format”.

NESTING_EVENT_ID, NESTING_EVENT_TYPE, NESTING_EVENT_LEVEL

Before MySQL 5.7.2, only NESTING_EVENT_ID and NESTING_EVENT_TYPE exist and are always NULL.

As of MySQL 5.7.2, all three columns exist and are used with other columns to provide information as follows for top-level (unnested) statements and nested statements (executed within a stored program).

For top level statements:

OBJECT_TYPE = NULL
OBJECT_SCHEMA = NULL
OBJECT_NAME = NULL
NESTING_EVENT_ID = NULL
NESTING_EVENT_TYPE = NULL
NESTING_LEVEL = 0

For nested statements:

OBJECT_TYPE = the parent statement object type
OBJECT_SCHEMA = the parent statement object schema
OBJECT_NAME = the parent statement object name
NESTING_EVENT_ID = the parent statement EVENT_ID
NESTING_EVENT_TYPE = 'STATEMENT'
NESTING_LEVEL = the parent statement NESTING_LEVEL plus one

The binary protocol. This is accessed through the MySQL C API and maps onto underlying server commands as shown in the following table.

The text protocol. This is accessed using SQL statements and maps onto underlying server commands as shown in the following table.

Statement preparation

A COM_STMT_PREPARE or SQLCOM_PREPARE command creates a prepared statement in the server. If the statement is successfully instrumented, a new row is added to the prepared_statements_instances table. If the statement cannot be instrumented, Performance_schema_prepared_statements_lost status variable is incremented.

Prepared statement execution

Execution of a COM_STMT_EXECUTE or SQLCOM_PREPARE command for an instrumented prepared statement instance updates the corresponding prepared_statements_instances table row.

Prepared statement deallocation

Execution of a COM_STMT_CLOSE or SQLCOM_DEALLOCATE_PREPARE command for an instrumented prepared statement instance removes the corresponding prepared_statements_instances table row. To avoid resource leaks, removal occurs even if the prepared statement instruments described previously are disabled.

OBJECT_INSTANCE_BEGIN

The address in memory of the instrumented prepared statement.

STATEMENT_ID

The internal statement ID assigned by the server. The text and binary protocols both use statement IDs.

STATEMENT_NAME

For the binary protocol, this column is NULL. For the text protocol, this column is the external statement name assigned by the user. For example, for the following SQL statement, the name of the prepared statement is stmt:

PREPARE stmt FROM 'SELECT 1';

SQL_TEXT

The prepared statement text, with ? placeholder markers.

OWNER_THREAD_ID, OWNER_EVENT_ID

These columns indicate the event that created the prepared statement.

OWNER_OBJECT_TYPE, OWNER_OBJECT_SCHEMA, OWNER_OBJECT_NAME

For a prepared statement created by a client session, these columns are NULL. For a prepared statement created by a stored program, these columns point to the stored program. A typical user error is forgetting to deallocate prepared statements. These columns can be used to find stored programs that leak prepared statements:

SELECT OWNER_OBJECT_TYPE, OWNER_OBJECT_SCHEMA, OWNER_OBJECT_NAME,
STATEMENT_NAME, SQL_TEXT
FROM performance_schema.prepared_statements_instances
WHERE OWNER_OBJECT_TYPE IS NOT NULL;

TIMER_PREPARE

The time spent executing the statement preparation itself.

COUNT_REPREPARE

The number of times the statement was reprepared internally (see Section 9.10.4, “Caching of Prepared Statements and Stored Programs”). Timing statistics for repreparation are not available because it is counted as part of statement execution, not as a separate operation.

COUNT_EXECUTE, SUM_TIMER_EXECUTE, MIN_TIMER_EXECUTE, AVG_TIMER_EXECUTE, MAX_TIMER_EXECUTE

Aggregated statistics for executions of the prepared statement.

SUM_xxx

The remaining SUM_xxx columns are the same as for the statement summary tables (see Section 23.9.15.3, “Statement Summary Tables”).

THREAD_ID, EVENT_ID

The thread associated with the event and the thread current event number when the event starts. The THREAD_ID and EVENT_ID values taken together form a primary key that uniquely identifies the row. No two rows will have the same pair of values.

END_EVENT_ID

This column is set to NULL when the event starts and updated to the thread current event number when the event ends.

EVENT_NAME

The name of the instrument from which the event was collected. This is a NAME value from the setup_instruments table. Instrument names may have multiple parts and form a hierarchy, as discussed in Section 23.4, “Performance Schema Instrument Naming Conventions”.

STATE

The current transaction state. The value is ACTIVE (after START TRANSACTION or BEGIN), COMMITTED (after COMMIT), or ROLLED BACK (after ROLLBACK).

TRX_ID

Unused.

GTID

This column changed in MySQL 5.7.6.

XID

The XA transaction identifier. It has the format described in Section 14.3.7.1, “XA Transaction SQL Syntax”. This column was removed in MySQL 5.7.7 and replaced with the XID_FORMAT_ID, XID_GTRID, and XID_BQUAL columns representing the components of XID values.

XID_FORMAT_ID, XID_GTRID, and XID_BQUAL

The components of the XA transaction identifier. They have the format described in Section 14.3.7.1, “XA Transaction SQL Syntax”. These columns were added in MySQL 5.7.7 as replacements for the XID column.

XA_STATE

The state of the XA transaction. The value is ACTIVE (after XA START), IDLE (after XA END), PREPARED (after XA PREPARE), ROLLED BACK (after XA ROLLBACK), or COMMITTED (after XA COMMIT).

SOURCE

The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved.

TIMER_START, TIMER_END, TIMER_WAIT

Timing information for the event. The unit for these values is picoseconds (trillionths of a second). The TIMER_START and TIMER_END values indicate when event timing started and ended. TIMER_WAIT is the event elapsed time (duration).

If an event has not finished, TIMER_END and TIMER_WAIT are NULL before MySQL 5.7.8. As of 5.7.8, TIMER_END is the current timer value and TIMER_WAIT is the time elapsed so far (TIMER_END − TIMER_START).

If an event is produced from an instrument that has TIMED = NO, timing information is not collected, and TIMER_START, TIMER_END, and TIMER_WAIT are all NULL.

For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 23.2.3.1, “Performance Schema Event Timing”.

ACCESS_MODE

The transaction access mode. The value is READ ONLY or READ WRITE.

ISOLATION_LEVEL

The transaction isolation level. The value is REPEATABLE READ, READ COMMITTED, READ UNCOMMITTED, or SERIALIZABLE.

AUTOCOMMIT

Whether autcommit mode was enabled when the transaction started.

NUMBER_OF_SAVEPOINTS, NUMBER_OF_ROLLBACK_TO_SAVEPOINT, NUMBER_OF_RELEASE_SAVEPOINT

The number of SAVEPOINT, ROLLBACK TO SAVEPOINT, and RELEASE SAVEPOINT statements issued during the transaction.

OBJECT_INSTANCE_BEGIN

Unused.

NESTING_EVENT_ID

The EVENT_ID value of the event within which this event is nested.

NESTING_EVENT_TYPE

The nesting event type. The value is TRANSACTION, STATEMENT, STAGE, or WAIT. (TRANSACTION will not appear because transactions cannot be nested.)

USER

The client user name for the connection. This is NULL for an internal thread, or for a user session that failed to authenticate.

HOST

The host from which the client connected. This is NULL for an internal thread, or for a user session that failed to authenticate.

CURRENT_CONNECTIONS

The current number of connections for the account.

TOTAL_CONNECTIONS

The total number of connections for the account.

HOST

The host from which the client connected. This is NULL for an internal thread, or for a user session that failed to authenticate.

CURRENT_CONNECTIONS

The current number of connections for the host.

TOTAL_CONNECTIONS

The total number of connections for the host.

USER

The client user name for the connection. This is NULL for an internal thread, or for a user session that failed to authenticate.

CURRENT_CONNECTIONS

The current number of connections for the user.

TOTAL_CONNECTIONS

The total number of connections for the user.

PROCESSLIST_ID

The connection identifier for the session.

ATTR_NAME

The attribute name.

ATTR_VALUE

The attribute value.

ORDINAL_POSITION

The order in which the attribute was added to the set of connection attributes.

PROCESSLIST_ID

The connection identifier for the session.

ATTR_NAME

The attribute name.

ATTR_VALUE

The attribute value.

ORDINAL_POSITION

The order in which the attribute was added to the set of connection attributes.

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

HOST

The master host that the slave is connected to. (CHANGE MASTER TO option: MASTER_HOST)

PORT

The port used to connect to the master. (CHANGE MASTER TO option: MASTER_PORT)

USER

The user name of the account used to connect to the master. (CHANGE MASTER TO option: MASTER_USER)

NETWORK_INTERFACE

The network interface that the slave is bound to, if any. (CHANGE MASTER TO option: MASTER_BIND)

AUTO_POSITION

1 if autopositioning is in use; otherwise 0. (CHANGE MASTER TO option: MASTER_AUTO_POSITION)

SSL_ALLOWED, SSL_CA_FILE, SSL_CA_PATH, SSL_CERTIFICATE, SSL_CIPHER, SSL_KEY, SSL_VERIFY_SERVER_CERTIFICATE, SSL_CRL_FILE, SSL_CRL_PATH

These columns show the SSL parameters used by the slave to connect to the master, if any.

SSL_ALLOWED has these values:

CHANGE MASTER TO options for the other SSL columns: MASTER_SSL_CA, MASTER_SSL_CAPATH, MASTER_SSL_CERT, MASTER_SSL_CIPHER, MASTER_SSL_CRL, MASTER_SSL_CRLPATH, MASTER_SSL_KEY, MASTER_SSL_VERIFY_SERVER_CERT.

Prior to MySQL 5.7.4, the value of SSL_CRL_PATH was not displayed correctly. (Bug #18174719)

CONNECTION_RETRY_INTERVAL

The number of seconds between connect retries. (CHANGE MASTER TO option: MASTER_CONNECT_RETRY)

CONNECTION_RETRY_COUNT

The number of times the slave can attempt to reconnect to the master in the event of a lost connection. (CHANGE MASTER TO option: MASTER_RETRY_COUNT)

HEARTBEAT_INTERVAL

The replication heartbeat interval on a slave, measured in seconds. Added in MySQL 5.7.5.

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

GROUP_NAME

This column is reserved for future use. Added in MySQL 5.7.6.

SOURCE_UUID

The server_uuid value from the master.

THREAD_ID

The I/O thread ID.

SERVICE_STATE

ON (thread exists and is active or idle), OFF (thread no longer exists), or CONNECTING (thread exists and is connecting to the master).

RECEIVED_TRANSACTION_SET

The set of global transaction IDs (GTIDs) corresponding to all transactions received by this slave. Empty if GTIDs are not in use. See GTID Sets for more information.

LAST_ERROR_NUMBER, LAST_ERROR_MESSAGE

The error number and error message of the most recent error that caused the I/O thread to stop. An error number of 0 and message of the empty string mean “no error.” If the LAST_ERROR_MESSAGE value is not empty, the error values also appear in the slave's error log.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

LAST_ERROR_TIMESTAMP

A timestamp in YYMMDD HH:MM:SS format that shows when the most recent I/O error took place.

LAST_HEARTBEAT_TIMESTAMP

A timestamp in YYMMDD HH:MM:SS format that shows when the most recent heartbeat signal was received by a replication slave. Added in MySQL 5.7.5.

COUNT_RECEIVED_HEARTBEATS

The total number of heartbeat signals that a replication slave received since the last time it was restarted or reset, or a CHANGE MASTER TO statement was issued. Added in MySQL 5.7.5.

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

DESIRED_DELAY

The number of seconds that the slave must lag the master. (CHANGE MASTER TO option: MASTER_DELAY)

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

SERVICE_STATE

Reserved for future use.

REMAINING_DELAY

If the slave is waiting for DESIRED_DELAY seconds to pass since the master applied an event, this field contains the number of delay seconds remaining. At other times, this field is NULL. (The DESIRED_DELAY value is stored in the replication_applier_configuration table.)

COUNT_TRANSACTIONS_RETRIES

Added in MySQL 5.7.5, shows the number of retries that were made because the slave SQL thread failed to apply a transaction.

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

THREAD_ID

The SQL/coordinator thread ID.

SERVICE_STATE

ON (thread exists and is active or idle) or OFF (thread no longer exists).

LAST_ERROR_NUMBER, LAST_ERROR_MESSAGE

The error number and error message of the most recent error that caused the SQL/coordinator thread to stop. An error number of 0 and message of the empty string mean “no error.” If the LAST_ERROR_MESSAGE value is not empty, the error values also appear in the slave's error log.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

All error codes and messages displayed in the LAST_ERROR_NUMBER and LAST_ERROR_MESSAGE columns correspond to error values listed in Section B.3, “Server Error Codes and Messages”.

LAST_ERROR_TIMESTAMP

A timestamp in YYMMDD HH:MM:SS format that shows when the most recent SQL/coordinator error occurred.

CHANNEL_NAME

The replication channel which this row is displaying. There is always a default replication channel, and more replication channels can be added. See Section 18.2.3, “Replication Channels” for more information.

WORKER_ID

The worker identifier (same value as the id column in the mysql.slave_worker_info table). After STOP SLAVE, the THREAD_ID column becomes NULL, but the WORKER_ID value is preserved.

THREAD_ID

The worker thread ID.

SERVICE_STATE

ON (thread exists and is active or idle) or OFF (thread no longer exists).

LAST_SEEN_TRANSACTION

The transaction that the worker has last seen. The worker has not necessarily applied this transaction because it could still be in the process of doing so.

If the gtid_mode system variable value is OFF, this column is ANONYMOUS, indicating that transactions do not have global transaction identifiers (GTIDs) and are identified by file and position only.

If gtid_mode is ON, the column value is defined as follows:

LAST_ERROR_NUMBER, LAST_ERROR_MESSAGE

The error number and error message of the most recent error that caused the worker thread to stop. An error number of 0 and message of the empty string mean “no error”. If the LAST_ERROR_MESSAGE value is not empty, the error values also appear in the slave's error log.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

All error codes and messages displayed in the LAST_ERROR_NUMBER and LAST_ERROR_MESSAGE columns correspond to error values listed in Section B.3, “Server Error Codes and Messages”.

LAST_ERROR_TIMESTAMP

A timestamp in YYMMDD HH:MM:SS format that shows when the most recent worker error occurred.

CHANNEL_NAME

Name of the group replication channel.

MEMBER_ID

Identifier for this member; same as the server UUID.

MEMBER_HOST

Network address of this member (host name or IP address).

MEMBER_PORT

Port on which the server is listening.

MEMBER_STATE

Current state of this member; can be any one of the following:

CHANNEL_NAME

Name of the group replication channel

VIEW_ID

Current view identifier for this group.

MEMBER_ID

Identifier for this member; same as the server UUID.

COUNT_TRANSACTIONS_IN_QUEUE

Number of transactions pending certification

COUNT_TRANSACTIONS_CHECKED

Number of transactions already certified by this member.

COUNT_CONFLICTS_DETECTED

Number of transactions that were negatively certified.

COUNT_TRANSACTIONS_VALIDATING

Number of transactions with which one can execute certification with them, but have not been garbage collected.

TRANSACTIONS_COMMITTED_ALL_MEMBERS

Set of stable group transactions.

LAST_CONFLICT_FREE_TRANSACTION

Latest transaction certified without conflicts.

Locks that have been granted (shows which sessions own which current metadata locks)

Locks that have been requested but not yet granted (shows which sessions are waiting for which metadata locks).

Lock requests that have been killed by the deadlock detector or timed out and are waiting for the requesting session's lock request to be discarded

When a metadata lock is requested and obtained immediately, a row with a status of GRANTED is inserted.

When a metadata lock is requested and not obtained immediately, a row with a status of PENDING is inserted.

When a metadata lock previously requested is granted, its row status is updated to GRANTED.

When a metadata lock is released, its row is deleted.

When a pending lock request is canceled by the deadlock detector to break a deadlock (ER_LOCK_DEADLOCK), its row status is updated from PENDING to VICTIM.

When a pending lock request times out (ER_LOCK_WAIT_TIMEOUT), its row status is updated from PENDING to TIMEOUT.

When granted lock or pending lock request is killed, its row status is updated from GRANTED or PENDING to KILLED.

The VICTIM, TIMEOUT, and KILLED status values are brief and signify that the lock row is about to be deleted.

The PRE_ACQUIRE_NOTIFY and POST_RELEASE_NOTIFY status values are brief and signify that the metadata locking subsubsystem is notifying interested storage engines while entering lock acquisition or leaving lock release operations. These status values were added in MySQL 5.7.11.

OBJECT_TYPE

The type of lock used in the metadata lock subsystem: The value is one of GLOBAL, SCHEMA, TABLE, FUNCTION, PROCEDURE, TRIGGER (currently unused), EVENT, COMMIT, USER LEVEL LOCK (a lock acquired with GET_LOCK()), or TABLESPACE.

For locks acquired using the locking service described in Section 26.3.1, “The Locking Service”, the OBJECT_TYPE is LOCKING SERVICE.

OBJECT_SCHEMA

The schema that contains the object.

OBJECT_NAME

The name of the instrumented object.

OBJECT_INSTANCE_BEGIN

The address in memory of the instrumented object.

LOCK_TYPE

The lock type from the metadata lock subsystem. The value is one of INTENTION_EXCLUSIVE, SHARED, SHARED_HIGH_PRIO, SHARED_READ, SHARED_WRITE, SHARED_UPGRADABLE, SHARED_NO_WRITE, SHARED_NO_READ_WRITE, or EXCLUSIVE.

LOCK_DURATION

The lock duration from the metadata lock subsystem. The value is one of STATEMENT, TRANSACTION, or EXPLICIT. The STATEMENT and TRANSACTION values are for locks that are released at statement or transaction end, respectively. The EXPLICIT value is for locks that survive statement or transaction end and are released explicitly, such as global locks acquired with FLUSH TABLES WITH READ LOCK.

LOCK_STATUS

The lock status from the metadata lock subsystem. The value is one of PENDING, GRANTED, VICTIM, TIMEOUT, KILLED, PRE_ACQUIRE_NOTIFY, or POST_RELEASE_NOTIFY. The Performance Schema assigns these values as described earlier in this section.

SOURCE

The name of the source file containing the instrumented code that produced the event and the line number in the file at which the instrumentation occurs. This enables you to check the source to determine exactly what code is involved.

OWNER_THREAD_ID

The thread requesting a metadata lock.

OWNER_EVENT_ID

The event requesting a metadata lock.

OBJECT_TYPE

The table opened by a table handle.

OBJECT_SCHEMA

The schema that contains the object.

OBJECT_NAME

The name of the instrumented object.

OBJECT_INSTANCE_BEGIN

The table handle address in memory.

OWNER_THREAD_ID

The thread owning the table handle.

OWNER_EVENT_ID

The event which caused the table handle to be opened.

INTERNAL_LOCK

The table lock used at the SQL level. The value is one of READ, READ WITH SHARED LOCKS, READ HIGH PRIORITY, READ NO INSERT, WRITE ALLOW WRITE, WRITE CONCURRENT INSERT, WRITE LOW PRIORITY, or WRITE. For information about these lock types, see the include/thr_lock.h source file.

EXTERNAL_LOCK

The table lock used at the storage engine level. The value is one of READ EXTERNAL or WRITE EXTERNAL.