ESQL: look to pushdown case insensitive functions #118304
Description
Description
Until #103599 gets resolved (one way or another), the common "pattern" for case insensitive filters is to use to_upper/to_lower against a given value, in order to preserve the filtering performance (and not convert it into a full scan):
...
| WHERE TO_UPPER(string_a) == "String" // this will never match since the value contains lower case chars
| WHERE TO_LOWER(string_b) == "abc" // rewritten as a case-insensitive term query
...
One way to achieve this is to identify the to_lower/to_upper == "value" pattern and replace it with InsensitiveEquals operator which can then be:
- either pushed down
- translated into a dedicated operator