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From "Vladimir Ozerov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IGNITE-4517) Add ability to execute SQL queries on certain partition(s)
Date Tue, 03 Jan 2017 07:31:58 GMT
Vladimir Ozerov created IGNITE-4517:

             Summary: Add ability to execute SQL queries on certain partition(s)
                 Key: IGNITE-4517
                 URL: https://issues.apache.org/jira/browse/IGNITE-4517
             Project: Ignite
          Issue Type: Task
          Components: SQL
            Reporter: Vladimir Ozerov
             Fix For: 2.0

This could be useful for certain cases:
1) Simple queries where partition can be determined easily in advance, either automatically
(IGNITE-4509, IGNITE-4510), or manually.
2) Spark data frame integration (IGNITE-3084)

*Proposed API*
class Query {
    int[] partitions();
    void partitions(int...);

Important points:
1) Partitions are defined in the very base {{Query}} class because we already has this feature
for {{ScanQuery}} and potentially any query type can benefit from it. If query doesn't support
partitions, exception should be thrown.
2) User should be able to specify multiple partitions, not only one. This will make our API
more flexible for 3-rd party integrations like Spark. Also it will help users with fine-grained
tuning. E.g. if user has a query {{... WHERE attribute IN (?, ?, ...)}}, he can determine
partitions for {{IN}} arguments in advance.

Probably this feature should not be supported for distributed joins. On the other hand - why
not? Query is always created from some cache, so the first map step can be executed only against
target partitions, and the rest execution flow can go through all partitions of other caches.

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