PostgreSQL has the ability to report the progress of certain commands during command execution. Currently, the only command which supports progress reporting is VACUUM. This may be expanded in the future.
Whenever VACUUM is running, the pg_stat_progress_vacuum view will contain one row for each backend (including autovacuum worker processes) that is currently vacuuming. The tables below describe the information that will be reported and provide information about how to interpret it. Progress reporting is not currently supported for VACUUM FULL and backends running VACUUM FULL will not be listed in this view.
表 28-20. pg_stat_progress_vacuum View
|pid||integer||Process ID of backend.|
|datid||oid||OID of the database to which this backend is connected.|
|datname||name||Name of the database to which this backend is connected.|
|relid||oid||OID of the table being vacuumed.|
|phase||text||Current processing phase of vacuum. See 表 28-21.|
|heap_blks_total||bigint||Total number of heap blocks in the table. This number is reported as of the beginning of the scan; blocks added later will not be (and need not be) visited by this VACUUM.|
|heap_blks_scanned||bigint||Number of heap blocks scanned. Because the visibility map is used to optimize scans, some blocks will be skipped without inspection; skipped blocks are included in this total, so that this number will eventually become equal to heap_blks_total when the vacuum is complete. This counter only advances when the phase is scanning heap.|
|heap_blks_vacuumed||bigint||Number of heap blocks vacuumed. Unless the table has no indexes, this counter only advances when the phase is vacuuming heap. Blocks that contain no dead tuples are skipped, so the counter may sometimes skip forward in large increments.|
|index_vacuum_count||bigint||Number of completed index vacuum cycles.|
|max_dead_tuples||bigint||Number of dead tuples that we can store before needing to perform an index vacuum cycle, based on maintenance_work_mem.|
|num_dead_tuples||bigint||Number of dead tuples collected since the last index vacuum cycle.|
表 28-21. VACUUM 的阶段