| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Usenet -> c.d.o.server -> Re: Best database for web backend on Linux?
On Wed, 21 Oct 1998 12:55:25 +0000, Evan Carew <ecarew_at_yahoo.com> wrote:
>Its interesting to note what is happening when Oracle is doing row level
>locking for you.
>On the server, in your working cache that oracle reserves for your queries
>(kind of like
>creating a shell for a user in UNIX), not only does Oracle have to track the
>pages you are
>working on, but it now has to keep track of all the rows you are thinking of
>updating. It also
>needs to "publish" any occurances of updates, locks and freed rows to other
>interested parties.
>This costs lots of clock cycles, not to mention memory.
>
>As an example, SAP on Oracle requires that you install at least 32Mb of ram PER
>USER
>on the server. Some of this is due to the way in which Oracle handles client
>access, but
>most of it is due to the overhead created by row level locking.
Evan,
again I can not agree with you. Oracle doesn't keep track of locked rows anywhere in the memory. It keeps this information in the header of the database block where locked row is located! So there surely can't be any substantial overhead with as you said "publishing any occurances of updates, locks and freed rows to other interested parties". Oracle simply doesn't "publish" any of those things anywhere to anyone. There is no way you can ever get a list of all rows that are locked, because this list is not kept anywhere. Only if you try to update/delete the locked row your action will fail because your transaction will find in the db block header that the row is locked.
Regards,
Jurij Modic <jmodic_at_src.si>
Certified Oracle7 DBA (OCP)
 |
 |