Answer
Parallel workers perform scans, joins, and aggregates. Parallelism depends on cost thresholds, table size, and query shape.
Quick Answer
Parallel queries split a sequential scan or aggregation across multiple worker processes. Controlled by max_parallel_workers_per_gather, max_parallel_workers, and min_parallel_table_scan_size. Workers each scan a portion of the table, results gathered and merged. Benefits for large analytical queries. Not useful for OLTP (queries return quickly, parallelism overhead exceeds benefit). Check EXPLAIN for "Gather" or "Gather Merge" nodes.
S
SugharaIQ Editorial Team
Verified Answer
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Source: SugharaIQ