track_io_timing

Enables timing of database I/O calls. This parameter is off by default, as it will repeatedly query the operating system for the current time, which may cause significant overhead on some platforms. You can use the pgtesttiming tool to measure the overhead of timing on your system. I/O timing information is displayed in pg_stat_database, in the output of sql-explain when the BUFFERS option is used, by autovacuum for auto-vacuums and auto-analyzes, when log_autovacuum_min_duration is set and by pgstatstatements. Only superusers can change this setting.