IPC - ParallelBitmapScan
Waiting for parallel bitmap scan to become initialized.
ParallelBitmapScan is an Inter Process Communication (IPC) wait and is seen when the planner selects a Parallel Bitmap Scan execution path. Scan processes need to be acquired and a dynamic shared memory (DSM) segment created.
Parallel queries are excellent at scanning large amounts of data the quickly returning results. Run in isolation or in a considered manner they are a useful tool.
Do not allow concurrent parallel queries from many users to flood system CPU or IO resources.