Re: Concurrent updates / low performance

have you any bitmap indexes on the table?

leonardo_ladeira_at_yahoo.com (Leonardo Ladeira) wrote in message news:<698f7e0a.0209261925.505371a_at_posting.google.com>...
> Hi,
>
> I hope anybody can help me on this issue....
>
> I use Oracle 8 running over AIX 4.3
>
> My application has only one table and a lot of concurrent updates (up
> to 15 per second). I made an embedded SQL function using host arrays
> to update a couple of rows (aprox 86) from the table.
>
> When I call this function once (1 single thread), it takes aprox 0.8s
> to execute.
>
> However, if I have 15 different threads calling this function at the
> same time, one single update can take up to 12 seconds!!! And all the
> 15 updates are related to DIFFERENT rows. The fastest update from the
> 15 takes at least 6 seconds!
>
> So, what I can't understand is:
>
> 1) Doesn't update command acquire a row-level locking by default? So
> why updates are influencing the execution time from each other, as
> they are not trying to modify same rows? Do I have to configure
> anything to make update acquire the row-level locking?
>
> 2) Considering that for any reason the update operation for a table is
> serialized, which means that one can take place only after the other
> has finished, why the first update (which is the fastest) takes longer
> (6 seconds) than when I tried a single update (0.8 s)?
>
> 3) Is there any way I can disable locking from oracle update
> operation? I could at application level guarantee data integrity.
>
>
> Please any advise is welcome!
>
> Thank you very much,
>
> Leonardo.
Received on Fri Sep 27 2002 - 12:39:18 CEST