MySQL SYS Schema Deep Dive

Copyright © 2016, Oracle and/or its affiliates. All rights reserved.
MySQL SYS Schema
Deep Dive
Mark Leith
Senior Software Development Manager
MySQL Enterprise Tools, Oracle

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. |
Program Agenda
Introduction to the MySQL sys schema
Installation
Formatting / Helper Routines
Summary Views
Tracing Routines
1
2
3
4
5

Why the sys schema?
• Performance Schema exposes a huge amount of data
• Many of its tables can implement multiple different use cases,
depending on the type of data
• The sys schema layers on top the (sometimes complex) queries in to a
packaged set of easy to use views
• It also adds a number of functions and procedures that help format,
configure the output of, and record, Performance Schema data
• Implements many of the common day to day DBA and Developer
debugging and tuning use cases

Installation from the command line
• $ git clone https://github.com/mysql/mysql-sys.git /tmp/sys
• $ cd /tmp/sys
• $ mysql -u user -p < sys_<version>.sql
<version> can be 56 or 57, for 5.6 and 5.7 respectively

Installation from MySQL Workbench 6.1+

Installation on the new MySQL 5.7 GA
• Do nothing other than install/mysql_upgrade it is there by default!
• You will be able to install future upgrades from the sys repository
as you wish, no restrictions there

select * from sys.version;
+-------------+---------------+
| sys_version | mysql_version |
+-------------+---------------+
| 1.5.1 | 5.7.14-log |
+-------------+---------------+
9
Checking sys is loaded
mysql> select *
-> from sys.schema_object_overview
-> where db = 'sys';
+-----+---------------+-------+
| db | object_type | count |
+-----+---------------+-------+
| sys | BASE TABLE | 1 |
| sys | INDEX (BTREE) | 1 |
| sys | TRIGGER | 2 |
| sys | FUNCTION | 22 |
| sys | PROCEDURE | 26 |
| sys | VIEW | 100 |
+-----+---------------+-------+

Program Agenda
Installation
Summary Views
Tracing Routines
1
3
2
4
5

• Make output human readable
• Format time appropriately
• Format bytes appropriately
• Truncate output for large
width values for CLI
• Extract object names
• Check instrumentation state
11
Formatting / Helper Functions
format_time
format_bytes
format_path
format_statement
extract_table_from_file_name
extract_schema_from_file_name
ps_is_account_enabled
ps_is_consumer_enabled
ps_is_instrument_default_enabled
ps_is_instrument_default_timed
ps_is_thread_instrumented

format_time() function
mysql> select format_time(23849723429) as time
-> union select format_time(8327423749233)
-> union select format_time(83274237492335);
+-------------+
| time |
+-------------+
| 23.85 ms |
| 8.33 s |
| 00:01:23.27 |
+-------------+

format_bytes() function
mysql> select format_bytes(23423) as bytes
-> union select format_bytes(23432423)
-> union select format_bytes(42839479283)
-> union select format_bytes(2293848203489);
+-----------+
| bytes |
+-----------+
| 22.87 KiB |
| 22.35 MiB |
| 39.90 GiB |
| 2.09 TiB |
+-----------+

Performance Schema Config Helper Procedures
• ps_setup_show_disabled() / ps_setup_show_enabled()
• ps_setup_disable_thread() / ps_setup_enable_thread()
• ps_setup_disable_background_threads() /
ps_setup_enable_background_threads()
• ps_setup_disable_instrument() / ps_setup_enable_instrument()
• ps_setup_disable_consumer() / ps_setup_enable_consumer()
• ps_setup_save() / ps_setup_reload_saved()
• ps_setup_reset_to_default() / ps_truncate_all_tables()

Program Agenda
Installation
Summary Views
Tracing Routines
1
4
2
3
5

MySQL sys views
• Reference set of views solving various administrator use cases
• Simple views, create/copy your own, sys is not “locked down”
• Build upon both performance_schema and INFORMATION_SCHEMA
• Both formatted and raw views are available
• All raw views are prefixed with x$
• Raw views are there for tools to poll
• Formatted views are for humans and the command line

• High level user/host overviews
• Breakdowns by:
• IO usage
• Stages
• Statement details
• Following show users only
17
User / Host Summary Views
user_summary
user_summary_by_file_io
user_summary_by_file_io_type
user_summary_by_stages
user_summary_by_statement_latency
user_summary_by_statement_type
host_summary
host_summary_by_file_io
host_summary_by_file_io_type
host_summary_by_stages
host_summary_by_statement_latency
host_summary_by_statement_type

user_summary view
mysql> select * from user_summaryG
*************************** 1. row ***************************
user: mark
statements: 3072
statement_latency: 1.77 s
statement_avg_latency: 575.29 us
table_scans: 7
file_ios: 20043
file_io_latency: 346.79 ms
current_connections: 1
total_connections: 1
unique_hosts: 1
current_memory: 515.81 KiB
total_memory_allocated: 30.69 MiB
MySQL 5.7

user_summary_by_file_io_type view
mysql> select * from user_summary_by_file_io_type;
+------+--------------------------------------+---------+-------------+-------------+
| user | event_name | total | latency | max_latency |
+------+--------------------------------------+---------+-------------+-------------+
| mark | wait/io/file/myisam/dfile | 19540 | 215.20 ms | 120.79 ms |
| mark | wait/io/file/myisam/kfile | 501 | 131.58 ms | 57.74 ms |
| mark | wait/io/file/sql/dbopt | 2 | 17.29 us | 9.17 us |
| root | wait/io/file/innodb/innodb_log_file | 2079432 | 00:28:27.62 | 1.30 s |
| root | wait/io/file/myisam/kfile | 5195927 | 00:17:07.33 | 1.17 s |
| root | wait/io/file/myisam/dfile | 1533813 | 00:07:27.59 | 1.18 s |
| root | wait/io/file/sql/binlog | 3517008 | 00:03:07.34 | 1.42 s |
| root | wait/io/file/innodb/innodb_data_file | 20720 | 00:02:37.81 | 492.23 ms |
| root | wait/io/file/sql/FRM | 41412 | 3.17 s | 80.43 ms |
| root | wait/io/file/sql/dbopt | 110993 | 1.23 s | 63.27 ms |

user_summary_by_statement_latency view
mysql> select * from user_summary_by_statement_latencyG
*************************** 1. row ***************************
user: mark
total: 176
total_latency: 1.26 s
max_latency: 583.33 ms
lock_latency: 216.95 ms
rows_sent: 311
rows_examined: 307
rows_affected: 0
full_scans: 7

user_summary_by_statement_type view
mysql> select * from user_summary_by_statement_typeG
*************************** 1. row ***************************
user: mark
statement: commit
total: 2463190
total_latency: 13.33h
max_latency: 12.18 s
lock_latency: 0 ps
rows_sent: 0
rows_examined: 0
rows_affected: 0
full_scans: 0

• IO by current threads
• Global summaries by file and
class, aggregating by bytes or
latency
• Stream of last file IO events in
raw form
22
IO Summary Views
io_by_thread_by_latency
io_global_by_file_by_bytes
io_global_by_file_by_latency
io_global_by_wait_by_bytes
io_global_by_wait_by_latency

io_by_thread_by_latency view
mysql> select * from io_by_thread_by_latencyG
*************************** 1. row ***************************
user: main
total: 1193
total_latency: 136.45 ms
min_latency: 731.38 ns
avg_latency: 269.99 us
thread_id: 1
processlist_id: NULL
*************************** 2. row ***************************
user: root@localhost
total: 533
total_latency: 53.81 ms
min_latency: 780.39 ns
avg_latency: 8.41 ms
thread_id: 23
processlist_id: 4

io_global_by_file_by_latency view
mysql> select * from io_global_by_file_by_latency limit 1G
*************************** 1. row ***************************
file: @@datadir/ibdata1
total: 1395714
total_latency: 00:28:53.06
count_read: 1006
read_latency: 4.51 s
count_write: 1326529
write_latency: 33.39 s
count_misc: 68179
misc_latency: 00:28:15.16

• Object overview
• Table usage statistics
• Index usage statistics
• Following show users only
26
Schema Analysis Views
schema_index_statistics
schema_object_overview
schema_table_statistics
schema_table_statistics_with_buffer
schema_tables_with_full_table_scans
schema_unused_indexes

schema_table_statistics view
mysql> select * from schema_table_statistics limit 1G
*************************** 1. row ***************************
table_schema: mem__quan
table_name: normalized_statements_by_server_by_schema_data
rows_fetched: 239685
fetch_latency: 17.10 s
rows_inserted: 1102895
insert_latency: 00:52:18.10
rows_updated: 55910
update_latency: 00:02:28.62
rows_deleted: 17899
delete_latency: 3.98 s
io_read_requests: 20639
io_read: 324.94 MiB
io_read_latency: 00:03:04.10
io_write_requests: 1965973
io_write: 40.36 GiB
io_write_latency: 25.46 s
io_misc_requests: 18217
io_misc_latency: 00:14:06.02

schema_index_statistics view
mysql> select * from schema_index_statistics limit 1G
*************************** 1. row ***************************
table_schema: mem__inventory
table_name: mysqlconnectionconfiguration
index_name: PRIMARY
rows_selected: 131399
select_latency: 00:07:05.03
rows_inserted: 0
insert_latency: 0 ps
rows_updated: 41608
update_latency: 21.96 s
rows_deleted: 0
delete_latency: 0 ps

schema_tables_with_full_table_scans view
mysql> select * from schema_tables_with_full_table_scans limit 10;
+--------------------+--------------------------------+-------------------+-----------+
| object_schema | object_name | rows_full_scanned | latency |
+--------------------+--------------------------------+-------------------+-----------+
| mem30__instruments | fsstatistics | 10207042 | 13.10 s |
| mem30__instruments | preparedstatementapidata | 436428 | 973.27 ms |
| mem30__instruments | mysqlprocessactivity | 411702 | 282.07 ms |
| mem30__instruments | querycachequeriesincachedata | 374011 | 767.15 ms |
| mem30__instruments | rowaccessesdata | 322321 | 1.55 s |
| mem30__instruments | connectionsmaxdata | 301242 | 857.63 ms |
| mem30__instruments | innodbdatadictionarymemorydata | 292564 | 495.38 ms |
| mem30__instruments | innodbbufferpooldata | 277112 | 1.95 s |
| mem30__instruments | avgrowaccessesdata | 269236 | 1.25 s |
| mem30__instruments | innodbrowdetailsdata | 248208 | 653.25 ms |
+--------------------+--------------------------------+-------------------+-----------+

• Wait summaries by class
• Wait details per:
• User
• Host
• Globally
31
Wait Analysis Views
wait_classes_global_by_avg_latency
wait_classes_global_by_latency
waits_by_host_by_latency
waits_by_user_by_latency
waits_global_by_latency

waits_global_by_latency view
mysql> select * from waits_global_by_latency limit 10;
+--------------------------------------+----------+---------------+-------------+-------------+
| events | total | total_latency | avg_latency | max_latency |
+--------------------------------------+----------+---------------+-------------+-------------+
| wait/io/table/sql/handler | 24196659 | 1.75h | 259.72 us | 2.29 s |
| wait/io/file/innodb/innodb_data_file | 5964255 | 1.36h | 822.01 us | 1.49 s |
| wait/io/file/innodb/innodb_log_file | 2272647 | 00:36:41.37 | 968.64 us | 1.30 s |
| wait/io/file/myisam/kfile | 5463587 | 00:18:14.16 | 200.26 us | 1.17 s |
| wait/io/file/myisam/dfile | 1715187 | 00:08:00.18 | 279.96 us | 1.18 s |
| wait/io/file/sql/binlog | 3722079 | 00:03:23.71 | 54.73 us | 1.42 s |
| wait/lock/table/sql/handler | 10074274 | 00:01:56.63 | 11.58 us | 186.90 ms |
| wait/io/socket/sql/client_connection | 3879827 | 25.36 s | 6.54 us | 219.25 ms |
| wait/io/file/sql/FRM | 43994 | 3.27 s | 74.35 us | 80.43 ms |
| wait/io/file/sql/dbopt | 116765 | 1.29 s | 11.03 us | 63.27 ms |
+--------------------------------------+----------+---------------+-------------+-------------+
InnoDB only instance, this MyISAM IO is all temporary tables, focus tuning there!

waits_by_user_by_latency view
mysql> select * from waits_by_user_by_latency;
+------+--------------------------------------+----------+---------------+-------------+-------------+
| user | event | total | total_latency | avg_latency | max_latency |
+------+--------------------------------------+----------+---------------+-------------+-------------+
| mark | wait/io/file/myisam/dfile | 19540 | 215.20 ms | 11.01 us | 120.79 ms |
| mark | wait/io/file/myisam/kfile | 501 | 131.58 ms | 262.63 us | 57.74 ms |
| mark | wait/io/file/sql/dbopt | 2 | 17.29 us | 8.64 us | 9.17 us |
| root | wait/io/table/sql/handler | 24189319 | 1.74h | 258.77 us | 2.29 s |
| root | wait/io/file/innodb/innodb_log_file | 2162650 | 00:30:52.87 | 856.76 us | 1.30 s |
| root | wait/io/file/myisam/kfile | 5460992 | 00:18:12.83 | 200.11 us | 1.17 s |
| root | wait/io/file/myisam/dfile | 1694624 | 00:07:59.50 | 282.95 us | 1.18 s |
| root | wait/io/file/sql/binlog | 3711637 | 00:03:23.16 | 54.74 us | 1.42 s |
| root | wait/io/file/innodb/innodb_data_file | 22577 | 00:03:05.73 | 8.23 ms | 492.23 ms |
| root | wait/lock/table/sql/handler | 10069000 | 00:01:56.59 | 11.58 us | 186.90 ms |
……
root is doing the most temporary table IO

• Table Metadata Lock Waits
• InnoDB Row Lock Waits
34
Lock Wait Views
schema_table_lock_waits
innodb_lock_waits

sys.schema_table_lock_waits
mysql> select * from sys.schema_table_lock_waitsG
*************************** 1. row ***************************
object_schema: test
object_name: t
waiting_thread_id: 43
waiting_pid: 21
waiting_account: msandbox@localhost
waiting_lock_type: SHARED_UPGRADABLE
waiting_lock_duration: TRANSACTION
waiting_query: alter table test.t add foo int
waiting_query_secs: 988
waiting_query_rows_affected: 0
waiting_query_rows_examined: 0
blocking_thread_id: 42
blocking_pid: 20
blocking_account: msandbox@localhost
blocking_lock_type: SHARED_NO_READ_WRITE
blocking_lock_duration: TRANSACTION
sql_kill_blocking_query: KILL QUERY 20
sql_kill_blocking_connection: KILL 20

sys.innodb_lock_waits
mysql> SELECT * FROM sys.innodb_lock_waitsG
*************************** 1. row ***************************
wait_started: 2014-11-11 13:39:20
wait_age: 00:00:07
wait_age_secs: 7
locked_table: `db1`.`t1`
locked_index: PRIMARY
locked_type: RECORD
waiting_trx_id: 867158
waiting_trx_started: 2014-11-11 13:39:15
waiting_trx_age: 00:00:12
waiting_trx_rows_locked: 0
waiting_trx_rows_modified: 0
waiting_pid: 3
waiting_query: UPDATE t1 SET val = val + 1 WHERE id = 2
waiting_lock_id: 867158:2363:3:3
waiting_lock_mode: X
blocking_trx_id: 867157
blocking_pid: 4
...
blocking_query: UPDATE t1 SET val …
blocking_lock_id: 867157:2363:3:3
blocking_lock_mode: X
blocking_trx_started: 2014-11-11 13:39:11
blocking_trx_age: 00:00:16
blocking_trx_rows_locked: 1
blocking_trx_rows_modified: 1
sql_kill_blocking_query: KILL QUERY 4
sql_kill_blocking_connection: KILL 4

• Statement overview
• Find statements by:
• Those with errors
• Those with full table scans
• Those creating temp tables
• Those that cause sorting
• With latency in 95th %ile
37
Statement Analysis Views
statement_analysis
statements_with_errors_or_warnings
statements_with_full_table_scans
statements_with_runtimes_in_95th_p
ercentile
statements_with_sorting
statements_with_temp_tables

statement_analysis view
mysql> select * from statement_analysis limit 2G
*************************** 1. row ***************************
query: INSERT INTO `mem30__quan` . `n ... nDuration` = IF ( VALUES ( ...
db: mem
full_scan:
exec_count: 4657
err_count: 0
warn_count: 0
max_latency: 10.54 s
avg_latency: 50.98 ms
lock_latency: 00:03:00.93
rows_sent: 0
rows_sent_avg: 0
rows_examined: 0
rows_examined_avg: 0
rows_affected: 4794
rows_affected_avg: 1
tmp_tables: 0
tmp_disk_tables: 0
rows_sorted: 0
sort_merge_passes: 0
digest: b98bfe333642e8e4e72c73515810d865
first_seen: 2014-09-24 11:27:01
last_seen: 2014-09-24 11:53:00

statements_with_errors_or_warnings view
mysql> select * from statements_with_errors_or_warnings limit 1G
*************************** 1. row ***************************
query: CREATE TEMPORARY TABLE IF NOT ... _logs` ( `id` INT8 NOT NULL )
db: mem
exec_count: 1725
errors: 1725
error_pct: 100.0000
warnings: 0
warning_pct: 0.0000
first_seen: 2014-05-20 10:42:32
last_seen: 2014-05-21 18:39:22
digest: 51fb979dbc3910a6294c7cdabd7839c3

statements_with_temp_tables view
mysql> select * from statements_with_temp_tables limit 1G
*************************** 1. row ***************************
query: SELECT * FROM ( SELECT `digest ... ` ,
`sum_no_index_used` AS ...
db: mysql
exec_count: 68
total_latency: 2.31 s
memory_tmp_tables: 476
disk_tmp_tables: 204
avg_tmp_tables_per_query: 7
tmp_tables_to_disk_pct: 43
first_seen: 2014-09-24 11:26:18
last_seen: 2014-09-24 12:33:00
digest: 50761c6a1818824328745d8a136b9ed6

statements_with_full_table_scans view
mysql> select * from statements_with_full_table_scans limit 1G
*************************** 1. row ***************************
query: SELECT `pojotimese0_` . `id` A ...
ty_timeseries` `pojotimese0_`
db: mem
exec_count: 1
total_latency: 940.89 us
no_index_used_count: 1
no_good_index_used_count: 0
no_index_used_pct: 100
rows_sent: 116
rows_examined: 116
rows_sent_avg: 116
rows_examined_avg: 116
first_seen: 2014-09-24 11:25:03
last_seen: 2014-09-24 11:25:03
digest: f81b5ce10baee9be754cf35fd245a516

• Expose summary memory
usage by host, thread and user
• Show global usage
• Based on Performance Schema
memory instruments (disabled by
default, these need enabling)
42
Memory Views
memory_by_host_by_current_bytes
memory_by_thread_by_current_bytes
memory_by_user_by_current_bytes
memory_global_by_current_bytes
memory_global_total

memory_global_by_current_bytes view
mysql> select * from sys.memory_global_by_current_bytes limit 5G
*************************** 1. row ***************************
event_name: memory/innodb/buf_buf_pool
current_count: 6
current_alloc: 785.62 MiB
current_avg_alloc: 130.94 MiB
high_count: 6
high_alloc: 785.62 MiB
high_avg_alloc: 130.94 MiB
*************************** 2. row ***************************
event_name: memory/innodb/os0file
current_count: 431
current_alloc: 52.51 MiB
current_avg_alloc: 124.76 KiB
high_count: 434
…
InnoDB Buffer Pool
InnoDB file IO memory usage (various)

memory_by_thread_by_current_bytes view
mysql> select * from sys.memory_by_thread_by_current_bytes
-> where user not like 'innodb%' and user not like 'sql%';
+-----------+----------------+--------------------+-------------------+-------------------+-------------------+-----------------+
| thread_id | user | current_count_used | current_allocated | current_avg_alloc | current_max_alloc | total_allocated |
+-----------+----------------+--------------------+-------------------+-------------------+-------------------+-----------------+
| 176167 | root@localhost | 67 | 633.36 KiB | 9.45 KiB | 256.00 KiB | 246.06 MiB |
| 176221 | root@localhost | 49 | 180.79 KiB | 3.69 KiB | 64.10 KiB | 766.13 KiB |
| 176201 | root@localhost | -33 | 122.04 KiB | -3787 bytes | 64.10 KiB | 14.55 MiB |
Note values can go negative if threads allocate
memory, but pass it to another thread to be freed,
this thread has freed memory from another thread

• Better SHOW PROCESSLIST
• No mutex contention
• Live statistics for query
• Consolidated metrics
45
Miscellaneous Views
processlist
session
metrics

processlist / session views
mysql> select * from sessionG
*************************** 1. row ***************************
thd_id: 7890
conn_id: 7870
user: root@localhost
db: mem
command: Query
state: update
time: 0
current_statement: /* mem dbpool.default */ inser ...<truncated>
lock_latency: 0 ps
rows_examined: 0
rows_sent: 0
rows_affected: 0
tmp_tables: 0
tmp_disk_tables: 0
full_scan: NO
last_statement: NULL
last_statement_latency: NULL
last_wait: wait/io/table/sql/handler
last_wait_latency: Still Waiting
source: handler.cc:7274

sys.sessions progress estimationmysql> select * from sys.sessionsG
*************************** 1. row ***************************
thd_id: 44524
conn_id: 44502
user: msandbox@localhost
db: test
command: Query
state: alter table (flush)
time: 18
current_statement: alter table t1 add column g int
statement_latency: 18.45 s
progress: 98.84
lock_latency: 265.43 ms
rows_examined: 0
rows_sent: 0
rows_affected: 0
tmp_tables: 0
tmp_disk_tables: 0
...

sys.metrics
mysql> select * from sys.metrics limit 199, 10;
+-----------------------------+----------------+--------------------------------------+---------+
| Variable_name | Variable_value | Type | Enabled |
+-----------------------------+----------------+--------------------------------------+---------+
| tc_log_page_waits | 0 | Global Status | YES |
| threads_cached | 7 | Global Status | YES |
| threads_connected | 3 | Global Status | YES |
| threads_created | 10 | Global Status | YES |
| threads_running | 3 | Global Status | YES |
| uptime | 275689 | Global Status | YES |
| uptime_since_flush_status | 275689 | Global Status | YES |
| adaptive_hash_pages_added | 0 | InnoDB Metrics - adaptive_hash_index | NO |
| adaptive_hash_pages_removed | 0 | InnoDB Metrics - adaptive_hash_index | NO |
| adaptive_hash_rows_added | 0 | InnoDB Metrics - adaptive_hash_index | NO |
+-----------------------------+----------------+--------------------------------------+---------+
performance_schema.global_status
information_schema.innodb_metrics

Program Agenda
Installation
Summary Views
Tracing Routines
1
5
2
3
4

• Dump all P_S data to a dot
graph file to trace a thread
• Look in the statement history
table to capture more info on
a statement digest
• Show detailed transaction info
• Dump as much diagnostics info
as possible (support enabler)
50
Statement Tracing Routines
ps_trace_thread
ps_trace_statement_digest
ps_thread_trx_info
ps_thread_stack
ps_statement_avg_latency_histogram
diagnostics

ps_trace_statement_digest procedure
• ps_trace_statement_digest() analyses live traffic looking for
certain statement digest for a period of time
• Captures statistics on each matching statement it finds
• Returns a report of the captured stats
• An overall summary
• A break down for the longest running example
• An EXPLAIN (if the statement is not truncated)

ps_trace_statement_digest procedure
• ps_trace_statement_digest() parameters
• in_digest The statement digest to analyse
• in_runtime How long to run analysis for
• in_interval How often to snapshot data
• in_start_fresh Whether to truncate P_S tables first
• in_auto_enable Whether to auto enable required config

ps_trace_statement_digest procedure example
mysql> call ps_trace_statement_digest(‘6134e9d6f25eb8e6cddf11f6938f202a’, 60, 1, true, true);
+--------------------+
| SUMMARY STATISTICS |
+--------------------+
| SUMMARY STATISTICS |
+--------------------+
1 row in set (59.93 sec)
+------------+-----------+-----------+-----------+---------------+------------+------------+
| executions | exec_time | lock_time | rows_sent | rows_examined | tmp_tables | full_scans |
+------------+-----------+-----------+-----------+---------------+------------+------------+
| 360 | 1.41 s | 138.39 ms | 720 | 0 | 0 | 0 |
+------------+-----------+-----------+-----------+---------------+------------+------------+
+--------------------------------+-------+-----------+
| event_name | count | latency |
+--------------------------------+-------+-----------+
| stage/sql/Sending data | 14 | 1.10 s |
| stage/sql/update | 198 | 667.34 ms |
| stage/sql/removing tmp table | 9 | 240.48 ms |
...

+---------------------------+
| LONGEST RUNNING STATEMENT |
+---------------------------+
| LONGEST RUNNING STATEMENT |
+---------------------------+
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
| thread_id | exec_time | lock_time | rows_sent | rows_examined | tmp_tables | full_scan |
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
| 23277 | 77.64 ms | 97.00 us | 2 | 0 | 0 | 0 |
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
+-------------------------------------------------------------------------------------------+
| sql_text |
+-------------------------------------------------------------------------------------------+
| /* mem dbpool.default */ insert into `mem__quan`.`normalized_statements_by_server_by_schema`
(firstSeen, lastSeen, normalized_statement_id, `schema`, server, id) values (1378983745000,
1378998600000, x'808ACEB88FC4B45BC47C4FE9D86C7F26', 'mem', '753c939e-1b99-11e3-b6d4-bc761a1f4f2f',
x'7CFE81F98B1E3FE0895D1AA2C39B326D') ON DUPLICATE KEY UPDATE ...
+-------------------------------------------------------------------------------------------+
...

sys.ps_thread_trx_info(<thread_id>)
SELECT sys.ps_thread_trx_info(48) as trx_infoG
*************************** 1. row ***************************
trx_info: [
{
"time": "790.70 us",
"state": "COMMITTED",
"mode": "READ WRITE",
"autocommitted": "NO",
"gtid": "AUTOMATIC",
"isolation": "REPEATABLE READ",
"statements_executed": [
{
"sql_text": "INSERT INTO info VALUES (1, 'foo')",
"time": "471.02 us",
"schema": "trx",
"rows_examined": 0,
"rows_affected": 1,
"rows_sent": 0,
"tmp_tables": 0,
"tmp_disk_tables": 0,
"sort_rows": 0,
"sort_merge_passes": 0
},
...
Pass in thread id

ps_trace_thread procedure
• ps_trace_thread() monitors a specific thread for a period
• Captures as much information on the thread activity as possible
• Returns a “dot” formatted file, that can graph the event hierarchy
• http://en.wikipedia.org/wiki/DOT_(graph_description_language)

ps_trace_thread procedure
• ps_trace_thread parameters
• in_thread_id The thread to analyse
• in_outfile The file to dump the data to (INTO OUTFILE)
• in_max_runtime How long to run analysis for
• in_interval How often to snapshot for data
• in_start_fresh Whether to truncate P_S tables first
• in_auto_setup Whether to auto enable required config
• in_debug Whether to also print debug info (source info)

ps_trace_thread procedure example
mysql> call ps_trace_thread(27768, '/tmp/stack_27768.dot', 60, 0.1, true, true, true);
+------------------------------------------------+
| Info |
+------------------------------------------------+
| Data collection starting for THREAD_ID = 27768 |
+------------------------------------------------+
+---------------------------------------------+
| Info |
+---------------------------------------------+
| Stack trace written to /tmp/stack_27768.dot |
+---------------------------------------------+
+--------------------------------------------------------+
| Convert to PDF |
+--------------------------------------------------------+
| dot -Tpdf -o /tmp/stack_27768.pdf /tmp/stack_27768.dot |
+--------------------------------------------------------+
+--------------------------------------------------------+
| Convert to PNG |
+--------------------------------------------------------+
| dot -Tpng -o /tmp/stack_27768.png /tmp/stack_27768.dot |
+--------------------------------------------------------+
1 row in set (60.90 sec)+

cerberus:~ mark$ more Documents/statement_graphs/deletes.dot
digraph events {
graph [rankdir=LR, nodesep="0.10"];
node [label="N"];
graph [bb="0,0,1860,17476"];
1 [label="(0.20μ) mysys/THR_LOCK_threadsn", style=filled, color=lightskyblue, pos="209,18", width="3.19", height="0.50"];
2 [label="(0.18μ) sql/THD::LOCK_thd_datan", style=filled, color=lightskyblue, pos="209,61", width="3.06", height="0.50"];
3 [label="(0.24μ) sql/hash_filo::lockn", style=filled, color=lightskyblue, pos="209,104", width="2.42", height=“0.50"];
4 [label="(0.31μ) sql/LOGGER::LOCK_logger - read_lockn", style=filled, color=orchid, pos="209,147", width="4.22",
height="0.50"];
5 [label="(0.08μ) sql/LOG::LOCK_logn", style=filled, color=lightskyblue, pos="209,190", width="2.64", height="0.50"];
6 [label="(12.97μ) wait/io/file/sql/query_log - write 49 bytesn/Users/mark/mysql/lp-mysql-trunk/mysql-test/var/mysqld.1/
mysqld.logn", style=filled, color=red, shape=box, pos="209,235", width="5.78", height="0.56"];
7 [label="(176.14μ) sql/selectnselect @@version_comment limit 1nerrors: 0nwarnings: 0nlock time: 0.00μnrows affected:
0nrows sent:
209,18", width="3.19", height="0.50"];mp disk tables: 0nselect scan: 0nselect full join: :
2 [label="(0.18μ) sql/THD::LOCK_thd_datan", style=filled, color=lightskyblue, pos="209,61", width="3.06", height="0.50"];
3 [label="(0.24μ) sql/hash_filo::lockn", style=filled, color=lightskyblue, pos="209,104", width="2.42", height="0.50"];
4 [label="(0.31μ) sql/LOGGER::LOCK_logger - read_lockn", style=filled, color=orchid, pos="209,147", width="4.22",
height="0.50"];
5 [label="(0.08μ) sql/LOG::LOCK_logn", style=filled, color=lightskyblue, pos="209,190", width="2.64", height="0.50"];
……

MySQL 5.7
Procedures
Transactions
Statements
Stages
Waits

Question time!

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