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Re: [Bacula-devel] small mysql patch


2008/8/31 Eric Bollengier <eric@xxxxxxxxxxxxxxxx>:
> Le Sunday 31 August 2008 21:32:16 Yuri Timofeev, vous avez écrit :
>> 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.
>
> it's why i suggest you to add them to dbcheck.c, if we add this to the default
> creation script, we can be sure that users will let them in place forever.
> And after, they will complain about performance problem.
>

If the problem only in dbcheck (and no problem with Verifies Jobs)
then have to change dbcheck.
Maybe I can do it later, I - beginner C programmer ;)

So I asked here (bacula-devel):
"What IDE, editors, plugins, utilities, etc. You use in developing the
bacula? In other words, are interested in your working environment. "
;)

>> > 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.
>
> Performance are much higher with few indexes, i'm not sure that mysql will
> insert million of rows at the same speed if you add 5 indexes.
>

Million files in a single Jobs? Maybe this is indeed a rare case.

>> > 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.
>>
>
> You can use them if your verify jobs are too slow. Many users don't use this
> feature. In bacula, you are free to modify indexes as you want.

I agree with you, but all these questions, imho, political:
whether bacula function normally "out of the box" (decision for a
large number of users / system administrators), or bacula will work
for hackers (who will explore SQL queries, create / delete indexes,
etc.).
For example, I often do not have time to do so.

No problem will not happen, imho, if Job will be 5-10 minutes longer,
and if the database will be at 5-10 Gb more.

>
>> > If you want to use new indexes with dbcheck, you can modify dbcheck.c in
>> > this way :

1. check that used mysql (?)
2. to verify the existence of indices, if not there, then :

>> >  - 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.
>
> This solution will not decrease support request about this subject, too few
> users are reading this document. Modify dbcheck is a better idea, if you
> can't work on it, perhaps we can add this to the project list.

I do not know.
On the other hand, it is really not the biggest problem.

For example, I am more concerned about progress on the problem from
the file projects:
"Item 8: Implement Copy pools" ;)
I'll do a separate message on this issue.


>
>> >> 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.405020
>> >>6%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.


	

-- 
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