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https://issues.apache.org/jira/browse/FLINK-40578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18112252#comment-18112252
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sepuri sai krishna commented on FLINK-40578:
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Could a committer please assign this to me? I have a fix ready.
> OVERLAY returns wrong results for several argument combinations
> ---------------------------------------------------------------
>
> Key: FLINK-40578
> URL: https://issues.apache.org/jira/browse/FLINK-40578
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Runtime
> Affects Versions: 2.0.0, 2.1.0, 2.2.0, 2.3.0
> Reporter: sepuri sai krishna
> Priority: Major
>
> The documentation says {{OVERLAY}} "replaces INT2 (STRING2's length by
> default) characters of STRING1 with STRING2 from position INT1". It does not,
> for the arguments below.
> {{E}} stands for the single character U+1F600 GRINNING FACE, so {{'aEb'}} is
> a three-character string whose middle character is that emoji. It is written
> this way to keep this description inside the Basic Multilingual Plane.
> || Expression || Returns || Expected ||
> | {{OVERLAY('abcdef' PLACING 'X' FROM 2 FOR 0)}} | {{aX}} | {{aXbcdef}} |
> | {{OVERLAY('abcdef' PLACING 'X' FROM 1 FOR 0)}} | {{X}} | {{Xabcdef}} |
> | {{OVERLAY('aEb' PLACING 'X' FROM 2 FOR 1)}} | {{a}}, {{X}}, then an
> unpaired low surrogate, then {{b}} | {{aXb}} |
> | {{OVERLAY('EE' PLACING 'X' FROM 1 FOR 1)}} | {{X}}, an unpaired low
> surrogate, then {{E}} | {{XE}} |
> | {{OVERLAY('abc' PLACING E FROM 2)}} | {{aE}} | {{aEc}} |
> | {{OVERLAY('123456789' PLACING 'abc' FROM 2 FOR 4294967301)}} | {{1abc789}}
> | {{1abc}} |
> | {{OVERLAY('123456789' PLACING 'abc' FROM 2 FOR 2147483647)}} |
> {{java.lang.StringIndexOutOfBoundsException}} | {{1abc}} |
> The first two rows need no unusual data at all.
> h3. Impact
> Silent data loss, with nothing logged. The rows producing an unpaired
> surrogate additionally return invalid UTF-16, which does not round-trip:
> encoding the result yields a replacement character or malformed bytes.
> h3. Affects
> master, and release-2.0 through release-2.3, where the implementation is
> byte-identical.
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