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From:Dan Nelson Date:June 16 2001 5:35pm
Subject:Re: What does tmp_table_size *really* do?
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In the last episode (Jun 16), Jeremy Zawodny said:
> Ah, thanks. The funny thing is that I *did* think to check the source
> code for a different problem I ran into severl minutes later.
> 
> I'll have to poke at this some more. I just restarted with a 64MB
> maximum and one of my more common queries is still "Using
> temporary". I find it difficult to believe that I'm pulling enough
> data to fill a 64MB table. The entire dataset is about 6 times that
> size, and I know I'm not pulling even close to 1/6th of the data.

I think all "Using temporary" means is that mysql has to modify the
result set (i.e. sort or group it) before passing it to the client. 
The temp table will stay in RAM unless it gets larger than the
tmp_table_size value, so to tell whether a particular query needed an
on-disk temp table, you'll probably have to compare the
created_tmp_disk_tables stat value before and after the query.

-- 
	Dan Nelson
	dnelson@stripped
Thread
What does tmp_table_size *really* do?Jeremy Zawodny16 Jun
  • Re: What does tmp_table_size *really* do?Dan Nelson16 Jun
    • Re: What does tmp_table_size *really* do?Jeremy Zawodny16 Jun
      • Re: What does tmp_table_size *really* do?Dan Nelson16 Jun
        • Re: What does tmp_table_size *really* do?Jeremy Zawodny16 Jun
          • Re: What does tmp_table_size *really* do?Dan Nelson17 Jun
            • Re: What does tmp_table_size *really* do?Jeremy Zawodny17 Jun
    • Re: What does tmp_table_size *really* do?jaab16 Jun
      • Re: What does tmp_table_size *really* do?Kevin Whitney16 Jun
      • RE: What does tmp_table_size *really* do?Sander Pilon16 Jun