>> >Get the statistics on the various runs of the sub-procedure- reads,
>> writes, fetches, and marks.
>> No writes. 47 000 indexed reads.


>Lets try that one again.  I'd like both reads and fetches, with statistics
>for a run of the subquery that's fast and one that's slow.   Did you mean
>that computing one account balance involved forty-seven thousand indexed
>reads?   That's some account!

Yup. BUT, the weird thing is, it's that SAME account that is sometimes fast and 
sometimes slow. It just depends on what other table/account you've queried 
beforehand.


>Gstat will tell you how deep your indexes are.  Firebird indexes are very 
>broad based triangles, with a single page at the top, lots of pages on the 
>>next level down, and enormous numbers of pages on the level below that.
 >The taller (or deeper) the triangle, the slower it is.  The height and width 
 >are determined by page size and key size.  An index with four or more >levels 
 >is an indication that you should increase the page size for your database.  
 >Run gstat and search for the indexes used by this sub-procedure.

Max depth in the whole database is 3 ;-)

>I'm sure you mentioned it somewhere, but what is the database page size?
> And the cache size?

        Generation              1311 
        Page size               8192 
        ODS version             11.2 
        Oldest transaction      1292 
        Oldest active           1293 
        Oldest snapshot         1293 
        Next transaction        1294 
        Bumped transaction      1 
        Sequence number         0 
        Next attachment ID      9 
        Implementation ID       16 
        Shadow count            0 
        Page buffers            1000  <<<< was 150, but I tried increasing to 
see if it would make a difference - it didn't seem to have any effect
        Next header page        0 
        Database dialect        3 
        Creation date           Sep 11, 2012 11:43:22 
        Attributes              force write, no reserve 
         Sweep interval:         200000 
 

Reply via email to