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From:Martin Ramsch Date:September 11 1999 9:02pm
Subject:Re: SELECT from several tables
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On Sat, 1999-09-11 23:38:15 +0300, Tim Groove wrote:
> >For example, why not just use a single table, and then
> >    SELECT COUNT(*) FROM tab WHERE uid=###;
> 
> I can't because this table is very big (it's size is about 200MB
> every evening)
> Each new INSERT lasts for second or two when table become big enough
> (it has indexes and several "char" fields also) and other processes
> are locked and awaiting while INSERT will be done. I need about 400
> new INSERTs each minute, so I decided to split one big table to 24
> parts to speed up INSERT process.

Tim, unfortunately I don't have much experience with tables that big
and so what I'm going to say is just based on what I read, not on own
experience ...

- Can you maybe get rid of some of the indexes?  Each index will
  take some time to be updated for table changes (but I'm quite sure
  you're aware of that).

- Maybe INSERT DELAYED is an option for you?
  There's been some discussion here in the list on this topic ...

- And a maybe crazy idea: Because I assume, that updating the indexes
  is the main bottleneck, you maybe could go with two identical
  tables, one with only an index on an auto_increment field id, the
  other version fully indexed.  And then every five or ten minutes,
  you call
    INSERT INTO indexedtable
      SELECT *
      FROM nonindexedtable
      WHERE id > lastremeberedid;
   This "batch" insert should be faster than 1000s of single inserts.
   So (in my theory) you should have the fasted inserts possible
   on the input side (nonindexed table) and fast indexed selects
   on the output side, with the only drawback, that the latter data
   only is updated every some minutes.

- Another very different approach to solve your speed problem might be 
  in fiddling with some sort buffer sizes and the like, but there are
  other's more experienced to step in on this ... :)

Regards,
  Martin
-- 
Martin Ramsch <m.ramsch@stripped> <URL: http://home.pages.de/~ramsch/ >
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Thread
SELECT from several tablesTim Groove11 Sep
  • Re: SELECT from several tablesMartin Ramsch11 Sep
  • search engined e l   d h a n o a12 Sep
    • Re: search engineBenjamin David Hildred12 Sep
    • Re: search engineAlexander I. Barkov12 Sep
Re: SELECT from several tablesTim Groove12 Sep
  • Re: SELECT from several tablesMartin Ramsch12 Sep
    • Re: SELECT from several tablesPaul DuBois12 Sep