beliefer opened a new pull request #27432: [SPARK-28325][SQL]Support ANSI SQL: SIMILAR TO ... ESCAPE syntax URL: https://github.com/apache/spark/pull/27432 ### What changes were proposed in this pull request? `[ NOT ] SIMILAR TO <similar pattern> [ ESCAPE <escape character> ]` This is a ANSI SQL. For example: ``` SELECT 'abc' SIMILAR TO 'abc' AS `true`; SELECT 'abc' SIMILAR TO 'a' AS `false`; SELECT 'abc' SIMILAR TO '%(b|d)%' AS `true`; SELECT 'abc' SIMILAR TO '(b|c)%' AS `false`; ``` There are some mainstream database support the syntax. **PostgreSQL:** https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-SIMILARTO-REGEXP **Redshift:** https://docs.aws.amazon.com/redshift/latest/dg/pattern-matching-conditions-similar-to.html `SIMILAR TO` is similar to `RLIKE`, but with the following differences: 1. The `SIMILAR TO` operator returns true only if its pattern matches the entire string, unlike `RLIKE` behavior, where the pattern can match any portion of the string. 2. The regex string allow uses _ and % as wildcard characters denoting any single character and any string, respectively (these are comparable to . and .* in POSIX regular expressions). 3. The regex string allow uses escape character like `LIKE` behavior. 4. '.', '^' and '$' is not a meta character for `SIMILAR TO`. ### Why are the changes needed? Support ANSI SQL: `SIMILAR TO ... ESCAPE` syntax `SIMILAR TO ... ESCAPE ` has a lot of convenience compared to `RLIKE`. ### Does this PR introduce any user-facing change? No ### How was this patch tested? Exists and new UT
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