Table fragmentation

[bjverzal]

Hello *,

I have an Informix system running on a 6-way UNIX server. The server is 71% idle, but the users are saying the system is running slow. In the past, we've seen this happen when the on-site admins fail to run "update statistics".

My question: Is there any way I can tell the condition of the database to see if "update statistics" needs to be run ?

Thanks, Bill.

 

[GRP]

Hi,

The update statics should be done when extensive modifications to a table or when changes are made to tables that are used more frequently. You can monitor system activity and do update statictis.

Or else you can schedule the update staticts daily or alternative days based on your system activity. The update staticts can be made for a specific table which you feel that more activity takes place or on whole database. The update staticts puts an exclusive lock on the table/database on which it will be done.Hence, we scheduled update statictics daily in non peak hours on night. So plan it when there will be no users.

G.R.P.

 

[bjverzal]

Is there any way to tell if the UPDATE STATISTICS has recently been run ?

Thx, Bill.

 

[sybdba]

There is a table sysdistrib which store the tabid & date for the statistics updated tables.

Following query may be useful on user database.

select a.tabname, b.constructed
from systables a, sysdistrib b
where a.tabid=b.tabid
group by 1,2

-OR- run simple sql statment without group by clause.

This may help.

Regards,

Rajdeep Dongre