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Multiple locks

Multiple locks

2004-06-07       - By Issac Goldstand

 Back
I need to do some operations which insert mass amounts of records which then
must be sorted, and would like to use table locking.

The flow I 'm looking for is:
LOCK TABLE A WRITE LOW_PRIO
DELETE FROM TABLE A (This used to be TRUNCATE TABLE A, but that complained
when I started locking)
LOAD DATA INFILE ... REPLACE INTO TABLE A
LOCK TABLE B WRITE
*while* SELECT FROM TABLE A
*process data and then* REPLACE INTO TABLE B
DELETE FROM TABLE A (Also, used to be truncate)
UNLOCK TABLES

I don 't seem to be able to lock a and then b later.
I don 't want to lock B from the start, because the LOAD DATA might take a
while.
I don 't want to unlock and relock A, because other scripts may modify the
data...

Any suggestions, pointers, RTFMs? (I looked at 14.4.5 and links from there
already)
Thanks!
Issac


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