----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Add EXPLAIN for UPDATE/DELETE CREATION DATE..: Tue, 18 Aug 2009, 16:24 SUPERVISOR.....: Bothorsen IMPLEMENTOR....: COPIES TO......: CATEGORY.......: Client-BackLog TASK ID........: 51 (http://askmonty.org/worklog/?tid=51) VERSION........: Benchmarks-3.0 STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Psergey - Tue, 18 Aug 2009, 16:25)=-=- High-Level Specification modified. --- /tmp/wklog.51.old.12524 2009-08-18 16:25:52.000000000 +0300 +++ /tmp/wklog.51.new.12524 2009-08-18 16:25:52.000000000 +0300 @@ -1 +1,22 @@ +User interface +-------------- +EXPLAIN UPDATE ... and EXPLAIN DELETE ... statements will work and produce +a tabular output similar to EXPLAIN SELECT. + +Implementation +-------------- +The primary challenge will be to change UPDATE/DELETE code to first produce +action plan and then act on it (and not make decisions on the go as it +currently does). + +What EXPLAIN will show +---------------------- +* multi-table one will show the SELECT part as usual +* single-table statements will show an equivalent of access method. + +Besides that, we want to know +- if sorting will be used +- whether the UPDATE will occur on the fly or not. + +(print or not "Using filesort"...) DESCRIPTION: Add support for EXPLAIN UPDATE/DELETE (we'd like support for all potentially long statements, e.g. for ALTER TABLE, but this WL entry is limited to UPDATE/DELETE as they are most often requested, and code that handles them is similar and distinct from other statements). HIGH-LEVEL SPECIFICATION: User interface -------------- EXPLAIN UPDATE ... and EXPLAIN DELETE ... statements will work and produce a tabular output similar to EXPLAIN SELECT. Implementation -------------- The primary challenge will be to change UPDATE/DELETE code to first produce action plan and then act on it (and not make decisions on the go as it currently does). What EXPLAIN will show ---------------------- * multi-table one will show the SELECT part as usual * single-table statements will show an equivalent of access method. Besides that, we want to know - if sorting will be used - whether the UPDATE will occur on the fly or not. (print or not "Using filesort"...) ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)