----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Collect engine independent statistics on table columns and indexes to store it in persistent system tables CREATION DATE..: Wed, 04 Jan 2012, 04:11 SUPERVISOR.....: IMPLEMENTOR....: Igor COPIES TO......: Igor Knielsen Monty Psergey Sanja Sergei Timour Wlad CATEGORY.......: Server-BackLog TASK ID........: 248 (http://askmonty.org/worklog/?tid=248) VERSION........: Server-5.5 STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 120 (hours remain) ORIG. ESTIMATE.: 120 PROGRESS NOTES: DESCRIPTION: In a special mode the ANALYZE command will collect statistics on table cardinality, table columns and table indexes. This statistics will be stored in system tables table_stat, column_stat and index_stat. For any database table the system table table_stat will contain the number of rows in the table. For any table column the system table column_stat will contain min and max value, the share of null values, the average length of a column value, and the the average frequency of the column values. For any index defined on a database table the system table index_stat will contain number of records per every key prefix. This task will be implemented in 3 steps: 1. A pure back-port of the WL#4777 from mysql-5.4 code line will be performed. 2. New possibility to collect statistics only on specified columns and/or indexes will be added. 3. A new possibility to scan only a certain percentage of the table records in a pseudo-random manner will be added. The collected statistics is supposed to be used by the optimizer, but this will be an objective of some other task. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v4.0.0)