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Re: [Bacula-devel] small mysql patch


Hi

2008/8/31 Eric Bollengier <eric@xxxxxxxxxxxxxxxx>:
>
> Adding indexes will probably speed up dbcheck, but it will slow down the
> attribute insertion process and grow up the database.

I wrote earlier (see reference to the discussion), that dbcheck can't
complete the job for 3 days!
Once the necessary indexes were created, all work was completed
dbcheck for 3-5 minutes!
Therefore, I say NOT to increase the speed of dbcheck (though this
too), I say about NOT normal work dbcheck.

> So, we can say that speed of attribute insertion is much more important than
> dbcheck performance.

MySQL performs INSERT operations with a very high speed, thus slowing
the work should not be noticeable, IMHO.

>
> The dbcheck operation have to be run once per month, maybe twice per year.

I do understand (see comments in src/cats/make_mysql_tables.in:46,
revision 7535) that there are problems with Verifies Jobs.

>
> If you want to use new indexes with dbcheck, you can modify dbcheck.c in this
> way :
>  - ask to the user if he wants to add them (think about disk space)
>  - add them + run analyse
>  - run the cleanup operation
>  - remove them
>
> I'm not sure that all your indexes are useful, for example (FileId, JobId) is
> probably used to see if you have orphan jobids in File table. The Job table
> is very small compare to others, so the database engine won't use it.
>
> Here, it's not the type of your index that will be important, it's much more
> the size of the File table (hundred of million in my case) that will change
> the cost of your index.

I think the problem (dbcheck) and its solution can be described, for
example, in the section "Troubleshooting" in the documentation.
And then not need to change the source code.

>>
>> I believe that the results of this discussion concerns
>>
>> "[Bacula-users] Bacula 2.2.8, dbcheck never completes"
>> http://sourceforge.net/mailarchive/forum.php?thread_name=48A984BF.4050206%4
>>0umdnj.edu&forum_name=bacula-users
>>
>> requires a small patch, see attached file.
>>
>> Since all fields (which fall in the indices) type INTEGER  the size of
>> the indices will be low and increase speed dbcheck will be very
>> substantial.
>>
>> As you think?
>>



-- 
with best regards

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