How to Rewrite OR Conditions in GBase 8a to Fix Slow Query Plans

Queries using OR conditions in GBase 8a can cause significant performance degradation when the optimizer generates a poor execution plan. For filter predicates, developers can replace OR checks with DECODE or CASE WHEN expressions to consolidate multiple equality tests into a single condition. When OR appears across two columns, a CONCAT combined with a LIKE pattern can substitute for the original predicate. For LEFT JOIN queries with OR in the ON clause, the join can be split into two separate LEFT JOINs whose results are merged using COALESCE, though this approach is only valid when the right table matches at most one row per left row. All such rewrites are manual workarounds and must be validated for both correctness and performance gains in a test environment before production use.