Christian,
Is it possible to add index only for "EnvelopeID" since only this field is in
where clause?
May be it will speed up the queries..
24.05.2018, 14:47, "Ветошкин Владимир" <en-tra...@yandex.ru>:
> Thank you Christian for your kind words :)
>
> I rewrote queries as you said.
> It helped and now query completes in about 3 seconds. Anyway, it's better.
>
> Also I added text index for this base.
> And there are 2 records about index in the "Info View" panel:
> - apply text index for $envs_49
> - rewrite where clause(s)
> - simplify gflwor
> - pre-evaluate db:open("000999") to document-node() sequence
> - apply text index for $invenvs_51
> - rewrite where clause(s)
> - simplify gflwor
>
> I attached the file, which contains the full text from the panel.
>
> 24.05.2018, 13:12, "Christian Grün" <christian.gr...@gmail.com>:
>>> I thought about "random access patterns"
>>> But all databases are on one disk.
>>
>> I agree, this sounds confusing at first sight. Some more details: If
>> the same database is opened by multiple queries, only one instance
>> will be opened. The same data cursor is used to read data, and if the
>> data is accessed in parallel, this cursor will repeatedly moved,
>> leading to adverse access patterns. This may be not so bad if
>> different databases are accessed (in this case, we’ll have multiple
>> cursors). But it’s also possible to write queries that show the
>> opposite effect (slow parallel access on multiple databases, fast
>> parallel access on single databases), so it also depends on the
>> specific queries (if sequential scans are performed, if index access
>> is possible, etc.) and your data sets.
>>
>> In general, you benefit a lot if your queries take advantage of the
>> available index structures (see [1] for more information). You can
>> open the "Info View" panel in BaseX and look for hints to index
>> rewritings. In your specific query, I noticed that $qxml and $qxmldoc
>> point to the same node. Moreover, you it helps to use "where" clauses
>> as early as possible, so the first part of your query could possibly
>> be rewritten to...
>>
>> for $qxml in db:open('000999')
>> where $qxml/*:Envelope/*:Header/*:RoutingInf/*:EnvelopeID/text() = $envs
>> let $qdoc := ...
>> return $qxml
>>
>> Hope this helps,
>> Christian
>>
>> PS: As far as I can judge, your English is fine ;)
>>
>> [1] http://docs.basex.org/wiki/Indexes
>>
>>> So, why two queries to different databases complete in about 5 sec?
>>> And if these queries make to one database - it takes a long time...
>>>
>>>> by setting the PARALLEL option to 1
>>> It helped a bit. Now the second script is waiting for finishing the first.
>>> But I would like to see a parallel execution of these queries. Is it
>>> possible without long waiting?
>>> May be it is possible to load database (or some nodes) in memory to avoid
>>> heavy load the disk?
>>>
>>> 23.05.2018, 22:54, "Christian Grün" <christian.gr...@gmail.com>:
>>>> Hi Ветошкин (cc to the list),
>>>>
>>>> Maybe we find a way to speed up your queries; you can attach them to
>>>> your next mail.
>>>>
>>>> I guess that the parallel query execution leads to "random access
>>>> patterns" on disk. You can enforce one query at a time by setting the
>>>> PARALLEL option to 1 (see [1]).
>>>>
>>>> Hope this helps,
>>>> Christian
>>>>
>>>> [1] http://docs.basex.org/wiki/Options#PARALLEL
>>>>
>>>> On Wed, May 23, 2018 at 9:40 PM, Ветошкин Владимир <en-tra...@yandex.ru>
>>>> wrote:
>>>>> Hi, Christian!
>>>>>
>>>>> Thank you.
>>>>>
>>>>> I have two scripts, which make queries to one database.
>>>>> If I run these queries at different times, each of them completes in
>>>>> about 5
>>>>> sec.
>>>>> But if I run both scripts at one time, it takes about 40 sec.
>>>>>
>>>>> If the scripts make queries to different databases - it's ok, it takes
>>>>> about
>>>>> 5 sec.
>>>>>
>>>>> Is it possible to improve this situation?
>>>>>
>>>>> I tried to use this code to load database in main-memory:
>>>>> db:open('db1') update {}
>>>>> But it didn't help.
>>>>>
>>>>> I hope, you understand me :)
>>>>>
>>>>> 23.05.2018, 20:15, "Christian Grün" <christian.gr...@gmail.com>:
>>>>>
>>>>> Привет Ветошкин,
>>>>>
>>>>> Welcome to the list. Just send your question to this address.
>>>>>
>>>>> Best,
>>>>> Christian
>>>>>
>>>>> Ветошкин Владимир <en-tra...@yandex.ru> schrieb am Mi., 23. Mai 2018,
>>>>> 19:10:
>>>>>
>>>>> Hello!
>>>>>
>>>>> Sorry for my English.
>>>>> May I ask you some questions here or I have to write them on github?
>>>>>
>>>>> --
>>>>> С уважением,
>>>>> Ветошкин Владимир Владимирович
>>>>>
>>>>> --
>>>>> С уважением,
>>>>> Ветошкин Владимир Владимирович
>>>
>>> --
>>> С уважением,
>>> Ветошкин Владимир Владимирович
>
> --
> С уважением,
> Ветошкин Владимир Владимирович
--
С уважением,
Ветошкин Владимир Владимирович
