[FLINK-19755] Fix CEP documentation error of the example in 'After Match Strategy' section

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.11.0
• Fix Version/s: 1.11.3, 1.12.0
• Component/s: Documentation, Library / CEP
• Labels: pull-request-available
• Assignee: Jacky Lau
• Reporter: Jacky Lau
• Created: 22/Oct/20 01:57
• Updated: 27/Oct/20 02:07
• Resolved: 27/Oct/20 02:06

Description

 symbol   tax   price         rowtime
======== ===== ======= =====================
 XYZ      1     7       2018-09-17 10:00:01
 XYZ      2     9       2018-09-17 10:00:02
 XYZ      1     10      2018-09-17 10:00:03
 XYZ      2     5       2018-09-17 10:00:04
 XYZ      2     17      2018-09-17 10:00:05
 XYZ      2     14      2018-09-17 10:00:06


SELECT *
FROM Ticker
    MATCH_RECOGNIZE(
        PARTITION BY symbol
        ORDER BY rowtime
        MEASURES
            SUM(A.price) AS sumPrice,
            FIRST(rowtime) AS startTime,
            LAST(rowtime) AS endTime
        ONE ROW PER MATCH
        [AFTER MATCH STRATEGY]
        PATTERN (A+ C)
        DEFINE
            A AS SUM(A.price) < 30
    )
 

AFTER MATCH SKIP TO LAST A 

symbol   sumPrice        startTime              endTime
======== ========== ===================== =====================
 XYZ      26         2018-09-17 10:00:01   2018-09-17 10:00:04
 XYZ      15         2018-09-17 10:00:03   2018-09-17 10:00:05
 XYZ      22         2018-09-17 10:00:04   2018-09-17 10:00:06
 XYZ      17         2018-09-17 10:00:05   2018-09-17 10:00:06

Again, the first result matched against the rows #1, #2, #3, #4.Compared to the previous strategy, the next match includes only row #3 (mapped to A) again for the next matching.

Therefore, the second result matched against the rows #3, #4, #5.

The third result matched against the rows #4, #5, #6.

The last result matched against the rows #5, #6.

i think it will exist looping match when coming to 17, 14 using "AFTER MATCH SKIP TO LAST A "

Issue Links

• links to: GitHub Pull Request #13754