Subject | Re: [firebird-support] How to check if index selectivity is out of date? |
---|---|
Author | Salvatore Besso |
Post date | 2004-07-23T17:39:45Z |
hello Ann,
thank you for your reply.
a couple of seconds for all indexes.
spoke of non-unique. This means that there is no need to recompute for
primary keys and unique indexes?
Last question: I've noticed that when the database is just created, all
RDB$STATISTICS fields are null. Does this mean that it's recommended to
execute SET STATISTICS almost once before deploying the database? Is there
any negative impact leaving RDB$STATISTICS null?
Cheers
Salvatore
thank you for your reply.
> Running "set statistics" is not terribly expensiveyes, I've seen that for the database I'm asking for, it takes no more than
a couple of seconds for all indexes.
> and I would probably set up a script that ran throughthis was also my thought, a script launched as application starts. But you
> all non-unique indexes updating their statistics after
> every backup.
spoke of non-unique. This means that there is no need to recompute for
primary keys and unique indexes?
> before and after a resetWhat do you exacly mean for "reset"? Maybe before and after SET STATISTICS?
Last question: I've noticed that when the database is just created, all
RDB$STATISTICS fields are null. Does this mean that it's recommended to
execute SET STATISTICS almost once before deploying the database? Is there
any negative impact leaving RDB$STATISTICS null?
Cheers
Salvatore