ganos.parallel.degree — sets the default degree of parallelism for parallel operations in Ganos, the geospatial extension for PolarDB for PostgreSQL.
When a Ganos operation does not explicitly specify parallelism, Ganos uses this variable's value.
Data type
integer
Valid values
1 to 64. Default: 1.
Setting this variable to 1 runs Ganos operations serially (no parallelism). Higher values allow Ganos to use more parallel workers, which can improve throughput for compute-intensive spatial queries.
Usage notes
Actual parallelism may be lower than the configured value. The number of workers Ganos can use at runtime is constrained by PostgreSQL-level settings such as
max_parallel_workersandmax_parallel_workers_per_gather. If fewer workers are available, the operation runs with reduced parallelism.Each parallel worker consumes additional resources. A Ganos operation running with multiple parallel workers consumes more CPU, memory, and I/O than a serial operation. Start with a moderate value (for example, 4) and increase it based on observed query performance and system load.
Examples
Set the degree of parallelism for the current session:
SET ganos.parallel.degree = 4;Set the default for all new connections to a specific database:
ALTER DATABASE <your_database> SET ganos.parallel.degree = 4;Reset to the default value:
SET ganos.parallel.degree = DEFAULT;Related parameters
When tuning ganos.parallel.degree, also consider adjusting these PostgreSQL parameters:
max_parallel_workers— caps the total number of parallel workers across all operationsmax_parallel_workers_per_gather— limits how many workers a single query node can use