Quantcast

Start transaction from base transaction

classic Classic list List threaded Threaded
66 messages Options
1234
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Parallel execution

Dimitry Sibiryakov-3
20.04.2017 15:49, Leyne, Sean wrote:
> "select f from t1 union select f from t2" is ONE statement with 2 parts!
>
> "Attachment" refers to the connection between a client and the server, it does not imply anything about how the engine might decompose a statement or how the parts could/would be executed!

   It doesn't matter. If both parts are executed simultaneously, from technical POV they
have no difference from independent queries executed simultaneously in one attachment and
transaction.


--
   WBR, SD.

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Parallel execution

Dimitry Sibiryakov-3
In reply to this post by Vlad Khorsun-2
20.04.2017 16:20, Vlad Khorsun wrote:
>> even in the simplest cases like "select f from t1 union select f from t2"?
>    This case nor simplest nor better for parallel execution than "ordinary" "select * from t".

   Union used to produce plan SORT (T1 NATURAL), SORT(T2 NATURAL). Both record streams can
be fetched and sorted in parallel and then merged, right? And because of selects from
different tables, they won't race on data pages.


--
   WBR, SD.

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Parallel execution

Vlad Khorsun-2
20.04.2017 17:50, Dimitry Sibiryakov wrote:
> 20.04.2017 16:20, Vlad Khorsun wrote:
>>> even in the simplest cases like "select f from t1 union select f from t2"?
>>     This case nor simplest nor better for parallel execution than "ordinary" "select * from t".
>
>     Union used to produce plan SORT (T1 NATURAL), SORT(T2 NATURAL). Both record streams can
> be fetched and sorted in parallel and then merged, right? And because of selects from
> different tables, they won't race on data pages.

   No. This is very naive view on parallel query execution. Real implementations works
differently. There is a lot of info in the net about it.

Vlad


------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

[SPAM] Re: Start transaction from base transaction

Vlad Khorsun-2
In reply to this post by Molnár Attila
20.04.2017 10:12, Molnár Attila wrote:
> +1 for this feature. I would be very happy for this. Also it would be
> awesmone if this consistent view were accessible later in time (this
> woudl mean garbage collection blocking).

   Blocking of GC is the easiest part of this task. One need also to preserve
metadata that was valid at interesting moment of time. Also it is necessary
to teach engine to use that metadata (instead of current one) within attachment
working "in the past". To do it it is necessary to make "snapshot" of that
metadata and save it with an interesting moment. And this is still just tip
of the iceberg, i suspect...

Regards,
Vlad

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: [SPAM] Re: Start transaction from base transaction

Adriano dos Santos Fernandes-3
Em 20/04/2017 17:53, Vlad Khorsun escreveu:
> Also it is necessary
> to teach engine to use that metadata (instead of current one) within attachment
> working "in the past".
>

I'm doing a prototype implementation of this for active transactions,
i.e., the things I mentioned in this thread start.

I've it starting working, but implementation is very simple, weak and
almost non-tested at the moment.


Adriano

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: [SPAM] Re: Start transaction from base transaction

Molnár Attila
Awesome! :)

On 2017.04.21. 1:30, Adriano dos Santos Fernandes wrote:

> Em 20/04/2017 17:53, Vlad Khorsun escreveu:
>> Also it is necessary
>> to teach engine to use that metadata (instead of current one) within attachment
>> working "in the past".
>>
> I'm doing a prototype implementation of this for active transactions,
> i.e., the things I mentioned in this thread start.
>
> I've it starting working, but implementation is very simple, weak and
> almost non-tested at the moment.
>
>
> Adriano
>
> ------------------------------------------------------------------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel


------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
1234
Loading...