|Subject||Re: [firebird-support] Migrating from Super Classic FB 2.5.2 to SuperServer FB 3.0 could have a problems|
Just migrating from SC FB 2.5.2 to SS FB 3.0 (both in Win x64), i found a few problems :
1) Query that runs about 2-3 secs in SC FB 2.5.2, runs minutes in SS FB 3.0
Query is something like this :
Select a.col1,b.col1 from tbl1 a, tbl2 b where a.id = b.id and b.id in (select c.id from tbl3 c)
SS FB 3.0 uses different query plan that not use indices, no wonder it was so slow.
Changed query to :
Select a.col1,b.col1 from tbl1 a, tbl2 b, tbl3 c where a.id = b.id and b.id= c.id
Runs around 1-2 secs in SS FB 3.0, but runs minutes in SC FB 2.5.2
2) Since in FB 3.0, SS is able to use SMP & shared Db Cache, I tried to set Db Cache to 512 MB via gfix. It was without error.
First connection is OK & I could saw that the actual Db cache size is around 300 MB. But after connection closed & tried to connect again, FB raised an error, something like connection lost.
Changed Db Cache to 256 MB fixed th e problem. I think, for modern computer, 256 MB is too small.