Akanksha-kedia opened a new pull request, #18779:
URL: https://github.com/apache/pinot/pull/18779
## Description
Adds the SQL standard `TRANSLATE(string, from, to)` scalar function to
`StringFunctions`. This function performs character-level substitution: each
character in `from` is replaced by the corresponding character in `to`.
Characters in `string` that appear in `from` but have no corresponding `to`
character (i.e. `from` is longer than `to`) are deleted from the output.
This matches the behavior documented in PostgreSQL (`translate`), Oracle
(`TRANSLATE`), and Trino (`translate`).
### Examples
```sql
translate('hello', 'aeiou', 'AEIOU') → 'hEllO'
translate('abc', 'abc', 'xy') → 'xy' -- 'c' has no target →
deleted
translate('abcdef','ace', 'XY') → 'XbYdf' -- 'e' has no target →
deleted
translate('abc', 'abc', '') → '' -- all chars deleted
translate('hello', 'xyz', '123') → 'hello' -- no match → unchanged
```
### Implementation
Pure Java loop over the input string, using `String.indexOf()` to look up
each character in the `from` string. O(n × |from|) — same complexity as the
PostgreSQL implementation and appropriate for typical string sizes.
## Tests
Unit tests added in `StringFunctionsTest` covering: basic replacement,
deletion, no-op (no match), empty input, empty `from`, all-deleted output, and
duplicate characters in `from`.
## Checklist
- [x] New public API has documentation (Javadoc on the method)
- [x] Backward compatible change (new function, no existing behavior changed)
- [x] Follows existing `@ScalarFunction` patterns in `StringFunctions.java`
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