ignite-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Denis Magda <dma...@apache.org>
Subject Re: SQL query collocated flag
Date Tue, 10 Jan 2017 20:04:37 GMT

What does ‘more effective query plan’ exactly means? Will the aggregation happen on the
data nodes and why this flag set to ‘true’ leads to strange behavior described here [1]
which sounds like a bug?

As for the documentation how would you rewrite existed setCollocated explanation [2] so that
it becomes clearer what the flag is for and how it works? Please provide your doc version.

[1] http://apache-ignite-users.70518.x6.nabble.com/NOT-IN-in-ignite-td9861.html
[2] https://apacheignite.readme.io/docs/configuration-parameters#section--sqlfields-and-sqlfieldsquery-configuration-properties


> On Jan 10, 2017, at 9:13 AM, Sergi Vladykin <sergi.vladykin@gmail.com> wrote:
> Yes, this flag indeed is very obscure. Basically it means that if you have
> some query with aggregates (at the top level right now) and you know that
> you will do GROUP BY by affinity key, then Ignite can generate a more
> effective query plan with this flag set.
> Sergi
> 2017-01-10 2:22 GMT+03:00 Valentin Kulichenko <valentin.kulichenko@gmail.com
>> :
>> Folks,
>> One of the users faced an interesting case [1]. Basically, there is a
>> query [2] which returns correct result when collocated flag is not set, but
>> if it's true, several counts for each node is received by the client
>> without being aggregated. Is this expected? I'm also attaching the test
>> that reproduces behavior.
>> Actually, the flag seems to be very confusing and documentation
>> description [3] doesn't help a lot. I'm reading it and it's not clear what
>> has to be collocated, what would happen if I incorrectly set the flag to
>> true, etc. Probably, some examples could help. Can someone elaborate?
>> [1] http://apache-ignite-users.70518.x6.nabble.com/NOT-
>> IN-in-ignite-td9861.html
>> [2] SELECT count(*) as COUNT FROM Person p join table(joinId VARCHAR(50) =
>> ?) i on p.id = i.joinId
>> [3] https://apacheignite.readme.io/docs/configuration-
>> parameters#section--sqlfields-and-sqlfieldsquery-configuration-properties
>> -Val

  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message