Hi Jiayi, I don't think it should any difference what is the order in the SUBSET clause. The PATTERN clause specifies the definitive order of pattern variables. SUBSET clause just groups them as a single entity you can reference. Therefore LAST/FIRST/PREV/NEXT/AFTER MATCH etc. will take into account only order in the PATTERN clause.
Best, Dawid On 16/12/2018 08:07, Julian Hyde wrote: > I don’t understand MATCH_RECOGNIZE well enough to give an opinion. Is there a > query that gives different results on Oracle if you change the order of items > in SUBSET? > > It seems that the parser preserves the order of items in the subset, but the > SqlToRelConverter does not, hence the line "subsets=[[[DOWN, STRT]]” in > SqlToRelConverterTest.xml. I would be concerned if the parser re-ordered > things, but I am not too concerned about SqlToRelConverter unless the > semantics are wrong. > >> On Dec 14, 2018, at 12:37 AM, bupt_ljy <bupt_...@163.com> wrote: >> >> Hi all, >> It’s my first time to send emails to Calcite developers. It’s a really good >> project and many projects benefit from it. >> Now I’ve encountered a problem about the subsets for MATCH_RECOGNIZE in >> thetestMatchRecognizeSubset1() testing. From the results, I can tell >> that"subset stdn = (strt, down)"will be explained to "SUBSET \"STDN\" = >> (\"DOWN\", \"STRT\”)”, which confuses me. IMO, It’ll affect the result of >> functions like“FIRST” and“LAST”, which may not be what I want, although it >> works fine with“AVG” function. >> I’m not sure if this is a bug, or anyone can tell me how we arrive here? >> >> >> >> >> Best, >> Jiayi Liao
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