Subject Oldest Snapshot and Performance Issues
Author Greg Kay

We are using Classic server 1.52 on a Linux 8 Gb dual CPU opteron 242
with Windows clients. There are about 110 users with 450 connections
at peak times. Here is the output of a gstat -h taken during the day:

Database header page information:
Flags 0
Checksum 12345
Generation 572988
Page size 4096
ODS version 10.1
Oldest transaction 22951
Oldest active 319143
Oldest snapshot 317998
Next transaction 572981
Bumped transaction 1
Sequence number 0
Next attachment ID 0
Implementation ID 19
Shadow count 0
Page buffers 1000
Next header page 0
Database dialect 3
Creation date Oct 23, 2005 22:24:16

Variable header data:
Sweep interval: 0

My question is why is the "Oldest snapshot" considerably less than the
"Oldest active"? My understanding is that the "Oldest snapshot" should
be close to the "Oldest Active".

Also, assuming we can improve the transaction movement, what else can
we do to improve performance? We expect 20-30% growth in the number of
users per year. Based on the recent article on the Lock Manager in
"The Interbase and Firebird Developer Magazine" we have increased the
lock manager settings to the maximum with considerable improvement
(hash lengths have gone from min 700, avg 800, and max 900, to min 20,
avg 40, or max 60, and the mutex wait is down to 2.5%). Is there
anything else?