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27.4.4.25 The statement _performance _analyzer () Procedure

Inhoudsopgave

Creates a report of the statements running on the server. The views are calculated based on the overall and/or delta activity.

This procedure disables binary logging during its execution by manipulating the session value of the sql_log_bin system variable. That is a restricted operation, so the procedure requires privileges sufficient to set restricted session variables. See Section 5.1.9.1, “System Variable Privileges”.

Parameters

  • in_action ENUM('snapshot', 'overall', 'delta', 'create_tmp', 'create_table', 'save', 'cleanup'): The action to take. These values are permitted:

    • snapshot: Store a snapshot. The default is to make a snapshot of the current content of the Performance Schema events_statements_summary_by_digest table. By setting in_table, this can be overwritten to copy the content of the specified table. The snapshot is stored in the sys schema tmp_digests temporary table.

    • overall: Generate an analysis based on the content of the table specified by in_table. For the overall analysis, in_table can be NOW() to use a fresh snapshot. This overwrites an existing snapshot. Use NULL for in_table to use the existing snapshot. If in_table is NULL and no snapshot exists, a new snapshot is created. The in_views parameter and the statement_performance_analyzer.limit configuration option affect the operation of this procedure.

    • delta: Generate a delta analysis. The delta is calculated between the reference table specified by in_table and the snapshot, which must exist. This action uses the sys schema tmp_digests_delta temporary table. The in_views parameter and the statement_performance_analyzer.limit configuration option affect the operation of this procedure.

    • create_table: Create a regular table suitable for storing the snapshot for later use (for example, for calculating deltas).

    • create_tmp: Create a temporary table suitable for storing the snapshot for later use (for example, for calculating deltas).

    • save: Save the snapshot in the table specified by in_table. The table must exist and have the correct structure. If no snapshot exists, a new snapshot is created.

    • cleanup: Remove the temporary tables used for the snapshot and delta.

  • in_table VARCHAR(129): The table parameter used for some of the actions specified by the in_action parameter. Use the format db_name.tbl_name or tbl_name without using any backtick (`) identifier-quoting characters. Periods (.) are not supported in database and table names.

    The meaning of the in_table value for each in_action value is detailed in the individual in_action value descriptions.

  • in_views SET ('with_runtimes_in_95th_percentile', 'analysis', 'with_errors_or_warnings', 'with_full_table_scans', 'with_sorting', 'with_temp_tables', 'custom'): Which views to include. This parameter is a SET value, so it can contain multiple view names, separated by commas. The default is to include all views except custom. The following values are permitted:

Inhoudsopgave Haut

Configuration Options

statement_performance_analyzer() operation can be modified using the following configuration options or their corresponding user-defined variables (see Section 27.4.2.1, “The sys_config Table”):

  • debug, @sys.debug

    If this option is ON, produce debugging output. The default is OFF.

  • statement_performance_analyzer.limit, @sys.statement_performance_analyzer.limit

    The maximum number of rows to return for views that have no built-in limit. The default is 100.

  • statement_performance_analyzer.view, @sys.statement_performance_analyzer.view

    The custom query or view to be used. If the option value contains a space, it is interpreted as a query. Otherwise, it must be the name of an existing view that queries the Performance Schema events_statements_summary_by_digest table. There cannot be any LIMIT clause in the query or view definition if the statement_performance_analyzer.limit configuration option is greater than 0. If specifying a view, use the same format as for the in_table parameter. The default is NULL (no custom view defined).

To create a report with the queries in the 95th percentile since the last truncation of events_statements_summary_by_digest and with a one-minute delta period:

  1. Create a temporary table to store the initial snapshot.

  2. Create the initial snapshot.

  3. Save the initial snapshot in the temporary table.

  4. Wait one minute.

  5. Create a new snapshot.

  6. Perform analysis based on the new snapshot.

  7. Perform analysis based on the delta between the initial and new snapshots.

  1. mysql> CALL sys.statement_performance_analyzer('create_tmp', 'mydb.tmp_digests_ini', NULL);
  2. Query OK, 0 rows affected (0.08 sec)
  3.  
  4. mysql> CALL sys.statement_performance_analyzer('snapshot', NULL, NULL);
  5. Query OK, 0 rows affected (0.02 sec)
  6.  
  7. mysql> CALL sys.statement_performance_analyzer('save', 'mydb.tmp_digests_ini', NULL);
  8. Query OK, 0 rows affected (0.00 sec)
  9.  
  10. mysql> DO SLEEP(60);
  11. Query OK, 0 rows affected (1 min 0.00 sec)
  12.  
  13. mysql> CALL sys.statement_performance_analyzer('snapshot', NULL, NULL);
  14. Query OK, 0 rows affected (0.02 sec)
  15.  
  16. mysql> CALL sys.statement_performance_analyzer('overall', NULL, 'with_runtimes_in_95th_percentile');
  17. +-----------------------------------------+
  18. | Next Output                             |
  19. +-----------------------------------------+
  20. | Queries with Runtime in 95th Percentile |
  21. +-----------------------------------------+
  22. 1 row in set (0.05 sec)
  23.  
  24. ...
  25.  
  26. mysql> CALL sys.statement_performance_analyzer('delta', 'mydb.tmp_digests_ini', 'with_runtimes_in_95th_percentile');
  27. +-----------------------------------------+
  28. | Next Output                             |
  29. +-----------------------------------------+
  30. | Queries with Runtime in 95th Percentile |
  31. +-----------------------------------------+
  32. 1 row in set (0.03 sec)
  33.  
  34. ...

Create an overall report of the 95th percentile queries and the top 10 queries with full table scans:

  1. mysql> CALL sys.statement_performance_analyzer('snapshot', NULL, NULL);
  2. Query OK, 0 rows affected (0.01 sec)                                
  3.  
  4. mysql> SET @sys.statement_performance_analyzer.limit = 10;
  5. Query OK, 0 rows affected (0.00 sec)        
  6.  
  7. mysql> CALL sys.statement_performance_analyzer('overall', NULL, 'with_runtimes_in_95th_percentile,with_full_table_scans');
  8. +-----------------------------------------+
  9. | Next Output                             |
  10. +-----------------------------------------+
  11. | Queries with Runtime in 95th Percentile |
  12. +-----------------------------------------+
  13. 1 row in set (0.01 sec)
  14.  
  15. ...
  16.  
  17. +-------------------------------------+
  18. | Next Output                         |
  19. +-------------------------------------+
  20. | Top 10 Queries with Full Table Scan |
  21. +-------------------------------------+
  22. 1 row in set (0.09 sec)
  23.  
  24. ...

Use a custom view showing the top 10 queries sorted by total execution time, refreshing the view every minute using the watch command in Linux:

  1. mysql> CREATE OR REPLACE VIEW mydb.my_statements AS
  2.        SELECT sys.format_statement(DIGEST_TEXT) AS query,
  3.               SCHEMA_NAME AS db,
  4.               COUNT_STAR AS exec_count,
  5.               sys.format_time(SUM_TIMER_WAIT) AS total_latency,
  6.               sys.format_time(AVG_TIMER_WAIT) AS avg_latency,
  7.               ROUND(IFNULL(SUM_ROWS_SENT / NULLIF(COUNT_STAR, 0), 0)) AS rows_sent_avg,
  8.               ROUND(IFNULL(SUM_ROWS_EXAMINED / NULLIF(COUNT_STAR, 0), 0)) AS rows_examined_avg,
  9.               ROUND(IFNULL(SUM_ROWS_AFFECTED / NULLIF(COUNT_STAR, 0), 0)) AS rows_affected_avg,
  10.               DIGEST AS digest
  11.          FROM performance_schema.events_statements_summary_by_digest
  12.        ORDER BY SUM_TIMER_WAIT DESC;
  13. Query OK, 0 rows affected (0.10 sec)
  14.  
  15. mysql> CALL sys.statement_performance_analyzer('create_table', 'mydb.digests_prev', NULL);
  16. Query OK, 0 rows affected (0.10 sec)
  17.  
  18. shell> watch -n 60 "mysql sys --table -e \"
  19. > SET @sys.statement_performance_analyzer.view = 'mydb.my_statements';
  20. > SET @sys.statement_performance_analyzer.limit = 10;
  21. > CALL statement_performance_analyzer('snapshot', NULL, NULL);
  22. > CALL statement_performance_analyzer('delta', 'mydb.digests_prev', 'custom');
  23. > CALL statement_performance_analyzer('save', 'mydb.digests_prev', NULL);
  24. > \""
  25.  
  26. Every 60.0s: mysql sys --table -e "        ...  Mon Dec 22 10:58:51 2014
  27.  
  28. +----------------------------------+
  29. | Next Output                      |
  30. +----------------------------------+
  31. | Top 10 Queries Using Custom View |
  32. +----------------------------------+
  33. +-------------------+-------+------------+---------------+-------------+---------------+-------------------+-------------------+----------------------------------+
  34. | query             | db    | exec_count | total_latency | avg_latency | rows_sent_avg | rows_examined_avg | rows_affected_avg | digest                           |
  35. +-------------------+-------+------------+---------------+-------------+---------------+-------------------+-------------------+----------------------------------+
  36. ...

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Document heeft de 26/06/2006 gemaakt, de laatste keer de 26/10/2018 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/mysql-rf-sys-statement-performance-analyzer.html

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Inhoudsopgave Haut