Re: Row pattern recognition

> By the way, I was thinking about eliminating recusrive calls in
> pattern matching. Attached is the first cut of the implementation. In
> the attached v8 patch:
>
> - No recursive calls anymore. search_str_set_recurse was removed.
>
> - Instead it generates all possible pattern variable name initial
> strings before pattern matching. Suppose we have "ab" (row 0) and
> "ac" (row 1). "a" and "b" represents the pattern variable names
> which are evaluated to true. In this case it will generate "aa",
> "ac", "ba" and "bc" and they are examined by do_pattern_match one by
> one, which performs pattern matching.
>
> - To implement this, an infrastructure string_set* are created. They
> take care of set of StringInfo.
>
> I found that the previous implementation did not search all possible
> cases. I believe the bug is fixed in v8.

The v8 patch does not apply anymore due to commit d060e921ea "Remove obsolete executor cleanup code".
So I rebased and created v9 patch. The differences from the v8 include:

- Fix bug with get_slots. It did not correctly detect the end of full frame.
- Add test case using "ROWS BETWEEN CURRENT ROW AND offset FOLLOWING".

Best reagards,
--
Tatsuo Ishii
SRA OSS LLC
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