Quick Answer
Troubleshoot plan regression: check if statistics are stale (ANALYZE), compare plans with pg_stat_statements before/after. Run EXPLAIN with and without indexes. Check if a new index was added (changed join order). Reset plan cache after schema changes. Set enable_seqscan=off to force index usage for testing. Use pg_hint_plan extension to force specific plans while debugging. Check for correlated columns needing multi-column stats.
Answer
Analyze EXPLAIN ANALYZE output to compare estimated vs actual row counts. Refresh statistics, increase default_statistics_target, create extended stats, add selective indexes, or rewrite queries. Correcting cardinality estimation is the core fix.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
