Hi Thomas,
I have a curious issue here, maybe someone can help.
I have a single process that inserts data into tables that contain purely logging information. This table is then searched by our Care department to troubleshoot issues. I am looking for the best way to store this data, and the structure on the backend.
There are 50 million inserts into table LOG a day. The primary index on the table is seconds from 1971. I only need to keep 60 days worth of data, and the table is only used for read purposes. This is my design criteria, but my problem is how to delete old data without crashing the log writer that is atteched to the table.
OK, how about this:
Use MyISAM and MERGE tables. Keep one table per day. E.g.:
log_2005_01_15 log_2005_01_16 log_2005_01_17 log_2005_01_18
etc.
Use MERGE tables to give you the 60 day (and perhaps e.g. 14 day, 30 day, 7 day, etc.) read views that you need, like so:
CREATE TABLE log_view_7day ( ... ) TYPE=MERGE UNION=( log_2005_01_12, log_2005_01_13, log_2005_01_14, log_2005_01_15, log_2005_01_16, log_2005_01_17, log_2005_01_18 );
Create another MERGE table for "today" using INSERT_METHOD:
CREATE TABLE log_view_today ( ... ) TYPE=MERGE INSERT_METHOD=FIRST UNION=( log_2005_01_18 );
You can then do all of your inserts from the log writer into the "today" table, and do your reads against the various MERGEs.
Every day at exactly midnight, you would use ALTER TABLE (which is atomic) to redefine the UNION of the MERGE definition of the various tables.
When you want to delete your "old" data, it's simply a matter of doing an ALTER TABLE to remove them from the MERGE, and using DROP TABLE to drop the log_yyyy_mm_dd table after that.
Also note that you could compress the old data and leave it live (but read only) in case you ever need it. myisampack can help you with that.
I hope that helps!
Regards,
Jeremy
-- Jeremy Cole Technical Yahoo - MySQL (Database) Geek
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