MySQL 5.7: Performance Schema Improvements

Copyright © 2014, Oracle and/or its affiliates. All rights reserved.Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Insert Information Protection Policy Classification from Slide 121

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Insert Information Protection Policy Classification from Slide 12
2
MySQL 5.7:
Performance Schema Improvements
Mark Leith
Senior Software Development Manager
MySQL @ Oracle

Copyright © 2014, Oracle and/or its affiliates. All rights reserved.3
Program Agenda
What is Performance Schema anyway?
Performance Schema in MySQL 5.5 & MySQL 5.6
Improvements made to date in MySQL 5.7
Things still to come
Questions (or ask along the way)

Know Your Audience
Using 5.1 (yes, still)?
Using 5.5 (but I’ll upgrade soon, honest)?
Using 5.6?
Using … 5.7?
Used Performance Schema?
#monitoringlove
#monitoringhate

What is Performance Schema anyway?

Introduced in MySQL 5.5
A storage engine, built for recording instrumentation
– PERFORMANCE_SCHEMA
– Manages fixed buffers in memory with lock free hashes
– Real engine, unlike INFORMATION_SCHEMA
A database schema to expose the instrumentation
– performance_schema
A set of interfaces in the MySQL Server wrapping calls to trace
– i.e. pthread_mutex_lock() -> mysql_mutex_lock()

Records latency of events that happen within the server
All latency exposed to picosecond precision
– Though tracked at different precisions internally
Also tracks other information as appropriate
– Bytes, source position, object metadata, etc.

Performance Schema in MySQL 5.5 & MySQL 5.6

Performance Schema in MySQL 5.5
Laid out the framework for instrumentation
Focused early on low level instruments
– Prove it could handle load, build from ground up
Not turned on by default, had some overhead issues

17 Tables
222 Instruments
Instrument Event Class
File IO wait/io/file/%
Mutexes wait/synch/mutex/%
Read/Write
Locks
wait/synch/rwlock/%
Conditions wait/synch/cond/%

Fixed lots of performance issues
Focused on bringing the instrumentation to the DBA / Developer
Statements / Statement Digests
Execution Stages
Object tracking (table / index IO, table locks)
Network IO
Turned on by default, with a subset of instrumentation disabled

52 Tables (+35)
545 Instruments (+323)
Instrument
Type
Event Class
Statements statement/%
Stages stage/%
Table IO wait/io/table/%
Table Locks wait/lock/table/%
Network IO wait/io/socket/%
Idle Timing idle

“I really think Performance Schema overhead is reasonable for most
workloads. …
On my old server I got some 20.2K QPS with Performance Schema
Disabled and 19.4 QPS with Performance Schema enabled which is
overhead of less than 5%.
For most workloads paying 5% to have insight about what is
happening with the system is a very fair trade.”
Peter Zaitsev, CEO, Percona
http://www.mysqlperformanceblog.com/2014/02/11/performance_schema-vs-slow-query-log/

Improvements made to date in MySQL 5.7

Insert Picture Here
17
Memory Usage
Metadata Locking
Replication Configuration & Status
Prepared Statements
Transactions
Stored Programs

75 Tables (+23)
784 Instruments (+239)
Instrument Type Event Class
Transactions transaction
Memory memory/%
Metadata Locks wait/lock/metadata/%

WL#3249
PERFORMANCE SCHEMA, Instrument memory usage

“Understanding where MySQL can allocate memory can help us to find
the cause in most cases. It is not as straightforward as it should be and
I‟m very hopeful future releases of MySQL, MariaDB or Drizzle bring
improvements in this space allowing us to see directly for what
purpose memory is allocated and so detect all kinds of memory usage
problems easier.”
Peter Zaitsev, CEO, Percona
http://www.mysqlperformanceblog.com/2012/03/21/troubleshooting-mysql-memory-usage/

Instrument memory usage
Added 212 different memory instrumentation types so far
Records current, high and low water marks of allocations
Does not track latency of memory allocation
5 new tables
memory_summary_by_account_by_event_name
memory_summary_by_host_by_event_name
memory_summary_by_thread_by_event_name
memory_summary_by_user_by_event_name
memory_summary_global_by_event_name

Instrument memory usage - global summary
mysql> SELECT * FROM sys.memory_global_by_current_allocatedG
*************************** 1. row ***************************
event_name: memory/performance_schema/internal_buffers
current_count: 60
current_alloc: 497.00 MiB
current_avg_alloc: 8.28 MiB
high_count: 60
high_alloc: 497.00 MiB
high_avg_alloc: 8.28 MiB
*************************** 2. row ***************************
event_name: memory/mysys/KEY_CACHE
current_count: 3
current_avg_alloc: 2.67 MiB
high_count: 3
high_alloc: 8.00 MiB
high_avg_alloc: 2.67 MiB

Instrument memory usage - thread summaries
mysql> select * from memory_by_thread_by_current_allocatedG
*************************** 1. row ***************************
user: sql/main
current_count: 2407
current_avg_alloc: 4.63 KiB
current_max_alloc: 8.00 MiB
total_allocated: 30.55 MiB
thread_id: 1
*************************** 2. row ***************************
user: mem@localhost
current_count: 1914
current_avg_alloc: 824 bytes
current_max_alloc: 816.67 KiB
total_allocated: 9.25 GiB
thread_id: 4336

Instrument memory usage - thread details
mysql> SELECT event_name,
-> sys.format_bytes(current_number_of_bytes_used) AS current_used
-> FROM performance_schema.memory_summary_by_thread_by_event_name
-> WHERE thread_id = 24
-> ORDER BY current_number_of_bytes_used DESC;
+-----------------------------------------------------+--------------+
| event_name | current_used |
+-----------------------------------------------------+--------------+
| memory/sql/Filesort_buffer::sort_keys | 255.94 KiB |
| memory/sql/sp_head::main_mem_root | 103.64 KiB |
| memory/mysys/IO_CACHE | 64.05 KiB |
| memory/mysys/lf_dynarray | 46.17 KiB |
| memory/mysys/array_buffer | 24.20 KiB |
| memory/sql/thd::main_mem_root | 23.95 KiB |
| memory/sql/String::value | 16.13 KiB |
| memory/sql/TABLE | 9.44 KiB |
| memory/sql/TABLE_SHARE::mem_root | 8.70 KiB |
| memory/myisam/MI_INFO | 7.07 KiB |
| memory/sql/THD::transactions::mem_root | 4.02 KiB |
| memory/myisam/MYISAM_SHARE | 3.29 KiB |
…

Instrument memory usage - other details
Disabled by default
Still requires InnoDB instrumentation
UPDATE setup_instruments
SET enabled = „YES‟
WHERE name LIKE „memory/%‟;

WL#5879
PERFORMANCE SCHEMA, MDL lock instrumentation

“Unfortunately, it‟s unlikely that I‟ll be able to create a reproducible test
case, because there‟s no way to actually see what is happening. I
hope that a future version of MySQL will include a more
comprehensive set of tables for inspecting locks, requests, and waits
at all layers of the server.”
Baron Schwartz, CEO, VividCortex
http://www.xaprb.com/blog/2012/08/28/debugging-metadata-locking-in-mysql-5-5/

MDL Lock Instrumentation
Added the wait/lock/metadata/sql/mdl instrument
2 new tables
metadata_locks
table_handles

MDL Lock Instrumentation
OBJECT_TYPE
GLOBAL, SCHEMA, TABLE, FUNCTION, PROCEDURE, TRIGGER, EVENT,
COMMIT
LOCK_TYPE
INTENTION_EXCLUSIVE, SHARED, SHARED_HIGH_PRIO,
SHARED_READ, SHARED_WRITE, SHARED_UPGRADABLE,
SHARED_NO_WRITE, SHARED_NO_READ_WRITE, EXCLUSIVE
LOCK_DURATION
STATEMENT, TRANSACTION, EXPLICIT
LOCK_STATUS
PENDING, GRANTED, VICTIM, TIMEOUT, KILLED

WL#3656
PERFORMANCE SCHEMA table for
SHOW SLAVE STATUS

Replication Instrumentation
6 new tables
replication_connection_configuration
replication_connection_status
replication_execute_configuration
replication_execute_status
replication_execute_status_by_coordinator
replication_execute_status_by_worker

Replication Connection Configuration
mysql> select * from performance_schema.replication_connection_configurationG
*************************** 1. row ***************************
HOST: 127.0.0.1
PORT: 3306
USER: rpl
NETWORK_INTERFACE:
AUTO_POSITION: 1
SSL_ALLOWED: YES
SSL_CA_FILE:
SSL_CA_PATH:
SSL_CERTIFICATE:
SSL_CIPHER:
SSL_KEY:
SSL_VERIFY_SERVER_CERTIFICATE: YES
SSL_CRL_FILE:
SSL_CRL_PATH:
CONNECTION_RETRY_INTERVAL: 40
CONNECTION_RETRY_COUNT: 10

Replication Connection Status
mysql> select * from replication_connection_statusG
*************************** 1. row ***************************
SOURCE_UUID:
THREAD_ID: NULL
SERVICE_STATE: CONNECTING
RECEIVED_TRANSACTION_SET:
LAST_ERROR_NUMBER: 1045
LAST_ERROR_MESSAGE: error connecting to master 'repl@localhost:5613' - retry-
time: 60 retries: 1
LAST_ERROR_TIMESTAMP: 2014-04-02 05:41:20

Replication Coordinator Status
mysql> select * from replication_execute_status_by_coordinatorG
*************************** 1. row ***************************
THREAD_ID: 1281
SERVICE_STATE: ON
LAST_ERROR_NUMBER: 0
LAST_ERROR_MESSAGE:
LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00
Status of Coordinator thread in multi-threaded replication

Replication Worker Status
mysql> select * from replication_execute_status_by_worker;
+-----------+-----------+---------------+-----------------------------------------+-------------------+--------------------+----------------------+
| WORKER_ID | THREAD_ID | SERVICE_STATE | LAST_SEEN_TRANSACTION | LAST_ERROR_NUMBER | LAST_ERROR_MESSAGE | LAST_ERROR_TIMESTAMP |
+-----------+-----------+---------------+-----------------------------------------+-------------------+--------------------+----------------------+
| 1 | 1282 | ON | | 0 | | 0000-00-00 00:00:00 |
| 2 | 1283 | ON | | 0 | | 0000-00-00 00:00:00 |
| 3 | 1284 | ON | | 0 | | 0000-00-00 00:00:00 |
| 4 | 1285 | ON | | 0 | | 0000-00-00 00:00:00 |
| 5 | 1286 | ON | | 0 | | 0000-00-00 00:00:00 |
| 6 | 1287 | ON | | 0 | | 0000-00-00 00:00:00 |
| 7 | 1288 | ON | | 0 | | 0000-00-00 00:00:00 |
| 8 | 1289 | ON | 181f2b36-a0b4-11e3-9ac7-1025863574a7:16 | 0 | | 0000-00-00 00:00:00 |
+-----------+-----------+---------------+-----------------------------------------+-------------------+--------------------+----------------------+
Status of worker threads within multi-threaded replication

WL#5768
PERFORMANCE SCHEMA, prepared statements
instrumentation

Prepared Statement Instrumentation
Instrumentation depends on already existing statement instruments
statement/com/prepare, statement/com/execute
statement/sql/prepare_sql, statement/sql/execute_sql
1 new table
prepared_statements_instances

Prepared Statement Instances
mysql> select * from performance_schema.prepared_statements_instancesG
*************************** 1. row ***************************
OBJECT_INSTANCE_BEGIN: 140198306602144
STATEMENT_ID: 1
STATEMENT_NAME: stmt1
SQL_TEXT: select * from test.t1
OWNER_THREAD_ID: 54003
OWNER_EVENT_ID: 935
OWNER_OBJECT_TYPE: NULL
OWNER_OBJECT_SCHEMA: NULL
OWNER_OBJECT_NAME: NULL
TIMER_PREPARE: 15386274000
COUNT_REPREPARE: 0
COUNT_EXECUTE: 1
SUM_TIMER_EXECUTE: 217699000
MIN_TIMER_EXECUTE: 217699000
AVG_TIMER_EXECUTE: 217699000
MAX_TIMER_EXECUTE: 217699000
SUM_LOCK_TIME: 0
SUM_ERRORS: 0
SUM_WARNINGS: 0
SUM_ROWS_AFFECTED: 0
SUM_ROWS_SENT: 0
SUM_ROWS_EXAMINED: 0
SUM_CREATED_TMP_DISK_TABLES: 0
SUM_CREATED_TMP_TABLES: 0
SUM_SELECT_FULL_JOIN: 0
SUM_SELECT_FULL_RANGE_JOIN: 0
SUM_SELECT_RANGE: 0
SUM_SELECT_RANGE_CHECK: 0
SUM_SELECT_SCAN: 0
SUM_SORT_MERGE_PASSES: 0
SUM_SORT_RANGE: 0
SUM_SORT_ROWS: 0
SUM_SORT_SCAN: 0
SUM_NO_INDEX_USED: 0
SUM_NO_GOOD_INDEX_USED: 0

WL#5864
PERFORMANCE SCHEMA, instrument
TRANSACTIONS

Added the transaction instrument
8 new tables
events_transactions_current
events_transactions_history
events_transactions_history_long
events_transactions_summary_by_account_by_event_name
events_transactions_summary_by_host_by_event_name
events_transactions_summary_by_thread_by_event_name
events_transactions_summary_by_user_by_event_name
events_transactions_summary_global_by_event_name

Transaction Instrumentation
Exposes details of transactions in raw or summary views
Show details such as
Transaction latency
Isolation levels
Auto commit
Savepoint info
GTID or transaction IDs
Link transactions to the statements within the transactions

Current Transaction Details
mysql> select * from events_transactions_currentG
*************************** 1. row ***************************
THREAD_ID: 1
EVENT_ID: 23733
END_EVENT_ID: 23742
EVENT_NAME: transaction
STATE: COMMITTED
TRX_ID: 281479898269256
GTID: NULL
XID: NULL
XA_STATE: NULL
SOURCE: handler.cc:1246
TIMER_START: 31140612726000
TIMER_END: 31140647445000
TIMER_WAIT: 34719000
ACCESS_MODE: READ WRITE
ISOLATION_LEVEL: REPEATABLE READ
AUTOCOMMIT: YES
NUMBER_OF_SAVEPOINTS: 0
NUMBER_OF_ROLLBACK_TO_SAVEPOINT: 0
NUMBER_OF_RELEASE_SAVEPOINT: 0
OBJECT_INSTANCE_BEGIN: NULL
NESTING_EVENT_ID: NULL
NESTING_EVENT_TYPE: NULL

Transaction Summary - per user
mysql> select * from events_transactions_summary_by_user_by_event_nameG
*************************** 1. row ***************************
USER: mem
EVENT_NAME: transaction
COUNT_STAR: 400044
SUM_TIMER_WAIT: 21208048458267000
MIN_TIMER_WAIT: 160744000
AVG_TIMER_WAIT: 53014289000
MAX_TIMER_WAIT: 24028520397000
COUNT_READ_WRITE: 400044
SUM_TIMER_READ_WRITE: 21208048458267000
MIN_TIMER_READ_WRITE: 160744000
AVG_TIMER_READ_WRITE: 53014289000
MAX_TIMER_READ_WRITE: 24028520397000
COUNT_READ_ONLY: 0
SUM_TIMER_READ_ONLY: 0
MIN_TIMER_READ_ONLY: 0
AVG_TIMER_READ_ONLY: 0
MAX_TIMER_READ_ONLY: 0

WL#5766
PERFORMANCE SCHEMA, stored programs
instrumentation

Stored Program Instrumentation
Tracks Stored Procedures, Stored Functions, Triggers and Events
Added 16 new statement/sp/% instruments
Expose the different work flows that stored programs use, such as
cursor operations, workflow controls etc.
Integrated in to the normal statement instrumentation
1 new tables
events_statements_summary_by_program

Stored Program Summary
mysql> select * from events_statements_summary_by_programG
*************************** 1. row ***************************
OBJECT_TYPE: PROCEDURE
OBJECT_SCHEMA: ps_demo
OBJECT_NAME: ps_demo_proc
COUNT_STAR: 1
SUM_TIMER_WAIT: 6970931000
MIN_TIMER_WAIT: 6970931000
AVG_TIMER_WAIT: 6970931000
MAX_TIMER_WAIT: 6970931000
COUNT_STATEMENTS: 5
SUM_STATEMENTS_WAIT: 6802181000
MIN_STATEMENTS_WAIT: 16372000
AVG_STATEMENTS_WAIT: 1360436000
MAX_STATEMENTS_WAIT: 6484366000
SUM_LOCK_TIME: 176401000000
SUM_ERRORS: 0
SUM_WARNINGS: 0
SUM_ROWS_AFFECTED: 1
SUM_ROWS_SENT: 0
SUM_ROWS_EXAMINED: 1
SUM_CREATED_TMP_DISK_TABLES: 0
SUM_CREATED_TMP_TABLES: 0
SUM_SELECT_FULL_JOIN: 0
SUM_SELECT_FULL_RANGE_JOIN: 0
SUM_SELECT_RANGE: 0
SUM_SELECT_RANGE_CHECK: 0
SUM_SELECT_SCAN: 0
SUM_SORT_MERGE_PASSES: 0
SUM_SORT_RANGE: 0
SUM_SORT_ROWS: 0
SUM_SORT_SCAN: 0
SUM_NO_INDEX_USED: 0
SUM_NO_GOOD_INDEX_USED: 0

Stored Program Instrumentation
Like Transaction instrumentation, stored programs link to the
statements within them, or even link to transactions within them,
which in turn link to their statements

Full Hierarchy of New Instrumentation

Things still to come

Status / Variable Instrumentation
Deprecate I_S.[GLOBAL|SESSION]_[STATUS|VARIABLES]
Replace with tables that show true state / aggregates
Per thread, user, host, account
See session statistics or configuration individually
Improve SHOW commands to only show appropriate variables
SHOW SESSION STATUS to only show session specific items
Backwards compatibility switch available
Less internal mutex contention for polling status

Further Replication Statistics
Redesigned lag monitoring
Consistently check lag across a replication chain
Further statistics on load of the replication threads
Queue lengths
Event counting
Busy times

Stage Progress Tracking
View the progress of longer stages of execution
Extends stage tables with “estimate” and “completed” columns
Bounded (“estimated”) or unbounded (only “completed” filled in)
Units depend on stage
stage/sql/copy to tmp table - 130 (rows) completed

Performance Schema Indexes
Add indexes for the PERFORMANCE_SCHEMA engine
Index key search fields across the schema
Will alleviate processing overhead for queries

Continued focus …
On performance!
On filling missing instrumentation points!
On consolidating instrumentation within Performance schema!

The preceding is intended to outline our general product direction. It is
intended for information purposes only, and may not be incorporated
into any contract.
It is not a commitment to deliver any material, code, or
functionality, and should not be relied upon in making purchasing
decisions. The development, release, and timing of any features or
functionality described for Oracle‟s products remains at the sole
discretion of Oracle.

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MySQL 5.7: Performance Schema Improvements

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