1 并行查询相关配置参数
2 并行扫描
3 并行聚合

1 并行查询相关配置参数

1.max_worker_processes(integer)
2.max_parallel_workers (integer)
3.max_parallel_workers_per_gather (integer)

max_worker_processes > max_parallel_workers > max_parallel_workers_per_gather

4.parallel_setup_cost(floating point) 默认为1000
5.parallel_tuple_cost(floating point) 默认为0.1

6. min_parallel_table_scan_size(integer) 默认值为8MB
7. min_parallel_index_scan_size(integer) 默认值为512kb
   8.force_parallel_mode (enum)

max_worker_processes = 16
max_parallel_workers = 8
max_parallel_workers_per_gather = 4    #taken from max_parallel_workers
parallel_tuple_cost = 0.1
parallel_setup_cost = 1000.0
min_parallel_table_scan_size = 8MB
min_parallel_index_scan_size = 512kB
force_parallel_mode = off

2 并行扫描

2.1 并行顺序扫描
2.2 并行索引扫描
2.3 并行index-only扫描
2.4 并行 bitmap heap扫描

3 并行聚合