Subject Re: [firebird-support] Migrating from Super Classic FB 2.5.2 to SuperServer FB 3.0 could have a problems
Author
Hi,
 
1. will be good to see this query plans
2. will be good to see exact error message
3. also check your db by gfix –validate –full
 
regards,
Karol Bieniaszewski
 
Sent: Sunday, May 1, 2016 8:35 AM
Subject: [firebird-support] Migrating from Super Classic FB 2.5.2 to SuperServer FB 3.0 could have a problems
 
 

Hi all,

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.

Regards,
Anto.