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7/12/2026
Optimizing OR Conditions in GBase 8a: Filter and Join Rewrites

Optimizing OR Conditions in GBase 8a: Filter and Join Rewrites

Short summary

A technical guide to optimizing OR conditions in GBase 8a SQL queries. For filter predicates, it shows rewriting OR checks using DECODE or CASE WHEN for single-column comparisons, and CONCAT with LIKE for multi-column OR. For join conditions, it demonstrates splitting a LEFT JOIN with OR into two separate joins merged via COALESCE, applicable only when the right table matches at most one row per left row.

  • •Rewrite OR filters using DECODE/CASE WHEN to enable index-friendly scans
  • •Multi-column OR can use CONCAT + LIKE pattern matching
  • •Split OR joins into two LEFT JOINs with COALESCE — only safe for 1:1 right-table matches

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