[jira] [Commented] (CALCITE-1935) Reference implementation for MATCH_RECOGNIZE

["Julian Feinauer (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16902397#comment-16902397 ] 

Julian Feinauer commented on CALCITE-1935:
------------------------------------------

Hey [~julianhyde], you assigned the issue back to me although I assigned it to you as its up to you to do the code review (which is what has to be done now). But please ping me, whenever I can assist you or answer questions.

> Reference implementation for MATCH_RECOGNIZE
> --------------------------------------------
>
>                 Key: CALCITE-1935
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1935
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Feinauer
>            Priority: Major
>              Labels: match
>
> We now have comprehensive support for parsing and validating MATCH_RECOGNIZE queries (see CALCITE-1570 and sub-tasks) but we cannot execute them. I know the purpose of this work is to do CEP within Flink, but a reference implementation that works on non-streaming data would be valuable.
> I propose that we add a class EnumerableMatch that can generate Java code to evaluate MATCH_RECOGNIZE queries on Enumerable data. It does not need to be efficient. I don't mind if it (say) buffers all the data in memory and makes O(n ^ 3) passes over it. People can make it more efficient over time.
> When we have a reference implementation, people can start playing with this feature. And we can start building a corpus of data sets, queries, and their expected result. The Flink implementation will be able to test against those same queries, and should give the same results, even though Flink will be reading streaming data.
> Let's create {{match.iq}} with the following query based on https://oracle-base.com/articles/12c/pattern-matching-in-oracle-database-12cr1:
> {code}
> !set outputformat mysql
> !use match
> SELECT *
> FROM sales_history MATCH_RECOGNIZE (
>          PARTITION BY product
>          ORDER BY tstamp
>          MEASURES  STRT.tstamp AS start_tstamp,
>                    LAST(UP.tstamp) AS peak_tstamp,
>                    LAST(DOWN.tstamp) AS end_tstamp,
>                    MATCH_NUMBER() AS mno
>          ONE ROW PER MATCH
>          AFTER MATCH SKIP TO LAST DOWN
>          PATTERN (STRT UP+ FLAT* DOWN+)
>          DEFINE
>            UP AS UP.units_sold > PREV(UP.units_sold),
>            FLAT AS FLAT.units_sold = PREV(FLAT.units_sold),
>            DOWN AS DOWN.units_sold < PREV(DOWN.units_sold)
>        ) MR
> ORDER BY MR.product, MR.start_tstamp;
> PRODUCT    START_TSTAM PEAK_TSTAMP END_TSTAMP         MNO
> ---------- ----------- ----------- ----------- ----------
> TWINKIES   01-OCT-2014 03-OCT-2014 06-OCT-2014          1
> TWINKIES   06-OCT-2014 08-OCT-2014 09-OCT-2014          2
> TWINKIES   09-OCT-2014 13-OCT-2014 16-OCT-2014          3
> TWINKIES   16-OCT-2014 18-OCT-2014 20-OCT-2014          4
> 4 rows selected.
> !ok
> {code}



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