What are the performance implications of using REGEXP on large text columns, and how can you optimize it?

Use Prefix Filters: Combine REGEXP with indexed columns—for example, filter by LEFT(), LIKE 'prefix%', or exact matches before applying REGEXP.

Create Generated Columns: Store simplified or extracted data in a generated column and index it.

Avoid Overly Complex Patterns: Simplify regex expressions to reduce backtracking.

Use Full-Text Indexing When Possible: For natural-language text search, prefer FULLTEXT indexes instead of REGEXP.

Limit Dataset Size: Apply WHERE conditions to narrow down rows before using REGEXP in the final filter.

Cache Prevalidated Fields: When validating emails/phones, store validated status instead of repeatedly scanning.