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                              WORKLOG TASK
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
TASK...........: Add EXPLAIN for UPDATE/DELETE
CREATION DATE..: Tue, 18 Aug 2009, 16:24
SUPERVISOR.....: Monty
IMPLEMENTOR....: 
COPIES TO......: 
CATEGORY.......: Client-BackLog
TASK ID........: 51 (http://askmonty.org/worklog/?tid=51)
VERSION........: Server-9.x
STATUS.........: Assigned
PRIORITY.......: 60
WORKED HOURS...: 0
ESTIMATE.......: 0 (hours remain)
ORIG. ESTIMATE.: 0

PROGRESS NOTES:

-=-=(Guest - Sat, 02 Jan 2010, 21:34)=-=-
Supervisor updated.
--- /tmp/wklog.51.old.21991     2010-01-02 21:34:01.000000000 +0200
+++ /tmp/wklog.51.new.21991     2010-01-02 21:34:01.000000000 +0200
@@ -1 +1 @@
-Bothorsen
+Monty

-=-=(Guest - Sat, 02 Jan 2010, 21:34)=-=-
Privacy level updated.
--- /tmp/wklog.51.old.21991     2010-01-02 21:34:01.000000000 +0200
+++ /tmp/wklog.51.new.21991     2010-01-02 21:34:01.000000000 +0200
@@ -1 +1 @@
-y
+n

-=-=(Guest - Sat, 02 Jan 2010, 21:33)=-=-
Version updated.
--- /tmp/wklog.51.old.21935     2010-01-02 19:33:25.000000000 +0000
+++ /tmp/wklog.51.new.21935     2010-01-02 19:33:25.000000000 +0000
@@ -1 +1 @@
-Benchmarks-3.0
+Server-9.x

-=-=(Guest - Sat, 02 Jan 2010, 21:33)=-=-
Status updated.
--- /tmp/wklog.51.old.21935     2010-01-02 19:33:25.000000000 +0000
+++ /tmp/wklog.51.new.21935     2010-01-02 19:33:25.000000000 +0000
@@ -1 +1 @@
-Un-Assigned
+Assigned

-=-=(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
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