PolarDB:OPT_PARAM hints

Parameter

Description

enable_hashjoin

Specifies whether to enable the query planner to use hash-join plan types.

enable_mergejoin

Specifies whether to enable the query planner to use merge-join plan types.

enable_nestloop

Specifies whether to enable the query planner to use nested-loop join plans. Nested-loop joins cannot be completely prohibited. However, if you disable this parameter, the planner prioritizes other methods.

enable_bitmapscan

Specifies whether to enable the query planner to use bitmap-scan plan types.

enable_indexonlyscan

Specifies whether to enable the query planner to use index-only-scan plan types.

enable_indexscan

Specifies whether to enable the query planner to use index-scan plan types.

enable_material

Specifies whether to enable the query planner to use materialization. Materialization cannot be completely prohibited. However, if you disable this parameter, the planner cannot insert materialization nodes.

enable_seqscan

Specifies whether to enable the query planner to use sequential scan plan types. Sequential scans cannot be completely prohibited. However, if you disable this parameter, the planner prioritizes other methods.

enable_sort

Specifies whether to enable the query planner to use explicit sort steps. Explicit sorts cannot be completely prohibited. However, if you disable this parameter, the planner prioritizes other methods.

enable_tidscan

Specifies whether to enable the query planner to use TID scan plan types.

enable_gathermerge

Specifies whether to enable the query planner to use gather-merge plan types.

enable_hashagg

Specifies whether to enable the query planner to use hashed aggregation plan types.

enable_parallel_append

Specifies whether to enable the query planner to use parallel-aware append plan types.

enable_parallel_hash

Specifies whether to enable the query planner to use hash-join plan types for parallel hashes. If hash-join plans are not enabled, this parameter does not take effect.

enable_partition_pruning

Specifies whether to enable the query planner to eliminate a partitioned table's partitions from query plans. It also controls the query planner's ability to generate query plans which allow the query executor to remove (ignore) partitions during query execution.

enable_partitionwise_aggregate

Specifies whether to enable the query planner to use partitionwise grouping or aggregation, which allows grouping or aggregation on a partitioned tables performed separately for each partition. If the GROUP BY clause does not include the partition keys, only partial aggregation can be performed on a per-partition basis, and finalization must be performed later.

enable_partitionwise_join

Specifies whether to enable the query planner to use partitionwise join, which allows a join between partitioned tables to be performed by joining the matching partitions. Partitionwise join currently applies only when the join conditions include all the partition keys, which must be of the same data type and have one-to-one matching sets of child partitions.