Subject Re: [firebird-support] About firebird performance
Author Hector Sánchez
Thanks Alexey,

Yes, I finally decided to try Firebird due to the very bad support form Embarcadero in migrating to newer version of IB. I must say I'm quite impressed with FB and start planning migrating to it if I manage to get same performance level that we have with IB.

I'll try what you suggest but I'm afraid this won't be the cause as it's a fresh new Db (just restored) with no user connected at all, as it's isolated in a server for testing purposes. So no transaction should be issued to it. However, if I had GC troubles I should see firebird process at higher CPU rates, shouldn't I?

I'll let you know.

El 5/9/2015, a las 11:59, Alexey Kovyazin ak@... [firebird-support] <> escribió:


Hi Hector,

So you finally decided to try Firebird - that's good.

I think that you are facing garbage collection problem - if there are a lot of record versions in the TABLE1 which are not interested to any transaction, your query will force garbage collection, and it can take some time.

How to check? run SELECT count(*) twice and compare execution times, and other query statistics (reads/writes).

Also, run gstat -a -r <database> and check information for TABLE1 - VERSIONS and MAX VERSIONS, if there are big numbers there, problem is certainly related with record versions, with the initial cause in wrong transactions management - i.e., long-running write transactions or forced rollbacks.

Alexey Kovyazin


I'm doing some basic tests with Firebird and I'm facing something I
cannot understand (I'm a newbie to Firebird which has worked with
IB7.5 for years, so I apologize if I ask something obvious):

- I have a linux server with firebird 2.5.4 Superserver: multi-core (4), 3GB RAM
- I placed a "huge" database: 1000 tables, 9GB
- When I issue a query like this "select count(*) from TABLE1" it
takes very long time to complete (>30 min).
- TABLE 1 has 3 million records

As I told you, I'm quite used to IB7.5, but I guess this is not normal
at all...probably I'm missing something but I couldn't find any
document which gives me an idea of what I'm doing wrong.

With same hardware an IB7.5 same query took 40 sec to complete (first
time issued, no cache).

Could anyone help?

Planatec Software S.L. ** <>
telf: +34 964 340 560 ** fax: +34 961 130 921

Planatec Software S.L. ** <>
telf: +34 964 340 560 ** fax: +34 961 130 921