9.6. WAL Writer Process
The WAL writer is a background process that periodically checks the WAL buffer and writes all unwritten XLOG records to the WAL segments. This process helps to avoid bursts of XLOG record writing. If the WAL writer is not enabled, writing XLOG records could be bottlenecked when a large amount of data is committed at once.
The WAL writer is enabled by default and cannot be disabled. The check interval is set to the configuration parameter wal_writer_delay, which defaults to 200 milliseconds.