27.4. Progress Reporting

PostgreSQL has the ability to report the progress of certain commands during command execution. Currently, the only commands which support progress reporting are ANALYZE, CLUSTER, CREATE INDEX, VACUUM, and BASE_BACKUP (i.e., replication command that pg_basebackup issues to take a base backup). This may be expanded in the future.

27.4.1. ANALYZE Progress Reporting

Whenever ANALYZE is running, the pg_stat_progress_analyze view will contain a row for each backend that is currently running that command. The tables below describe the information that will be reported and provide information about how to interpret it.

Table 27.32. pg_stat_progress_analyze View

Column Type Description
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 analyzed.
phase text Current processing phase. See Table 27.33.
sample_blks_total bigint Total number of heap blocks that will be sampled.
sample_blks_scanned bigint Number of heap blocks scanned.
ext_stats_total bigint Number of extended statistics.
ext_stats_computed bigint Number of extended statistics computed. This counter only advances when the phase is computing extended statistics.
child_tables_total bigint Number of child tables.
child_tables_done bigint Number of child tables scanned. This counter only advances when the phase is acquiring inherited sample rows.
current_child_table_relid oid OID of the child table currently being scanned. This field is only valid when the phase is acquiring inherited sample rows.

Table 27.33. ANALYZE phases

Phase	Description
initializing	The command is preparing to begin scanning the heap. This phase is expected to be very brief.
acquiring sample rows	The command is currently scanning the table given by relid to obtain sample rows.
acquiring inherited sample rows	The command is currently scanning child tables to obtain sample rows. Columns child_tables_total, child_tables_done, and current_child_table_relid contain the progress information for this phase.
computing statistics	The command is computing statistics from the sample rows obtained during the table scan.
computing extended statistics	The command is computing extended statistics from the sample rows obtained during the table scan.
finalizing analyze	The command is updating pg_class. When this phase is completed, ANALYZE will end.

Note

Note that when ANALYZE is run on a partitioned table, all of its partitions are also recursively analyzed as also mentioned in ANALYZE. In that case, ANALYZE progress is reported first for the parent table, whereby its inheritance statistics are collected, followed by that for each partition.

27.4.2. CREATE INDEX Progress Reporting

每當執行 CREATE INDEX 或 REINDEX 時，pg_stat_progress_create_index 檢視表的每一行會列出目前正在建立索引的每個後端程序。下表描述了其所回報的資訊，以及有關如何解釋的說明。

Table 27.34. pg_stat_progress_create_index View

Column Type Description
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 on which the index is being created.
index_relid oid OID of the index being created or reindexed. During a non-concurrent CREATE INDEX, this is 0.
command text The command that is running: CREATE INDEX, CREATE INDEX CONCURRENTLY, REINDEX, or REINDEX CONCURRENTLY.
phase text Current processing phase of index creation. See Table 27.35.
lockers_total bigint Total number of lockers to wait for, when applicable.
lockers_done bigint Number of lockers already waited for.
current_locker_pid bigint Process ID of the locker currently being waited for.
blocks_total bigint Total number of blocks to be processed in the current phase.
blocks_done bigint Number of blocks already processed in the current phase.
tuples_total bigint Total number of tuples to be processed in the current phase.
tuples_done bigint Number of tuples already processed in the current phase.
partitions_total bigint When creating an index on a partitioned table, this column is set to the total number of partitions on which the index is to be created.
partitions_done bigint When creating an index on a partitioned table, this column is set to the number of partitions on which the index has been completed.

Table 27.35. CREATE INDEX Phases

Phase	Description
initializing	CREATE INDEX or REINDEX is preparing to create the index. This phase is expected to be very brief.
waiting for writers before build	CREATE INDEX CONCURRENTLY or REINDEX CONCURRENTLY is waiting for transactions with write locks that can potentially see the table to finish. This phase is skipped when not in concurrent mode. Columns lockers_total, lockers_done and current_locker_pid contain the progress information for this phase.
building index	The index is being built by the access method-specific code. In this phase, access methods that support progress reporting fill in their own progress data, and the subphase is indicated in this column. Typically, blocks_total and blocks_done will contain progress data, as well as potentially tuples_total and tuples_done.
waiting for writers before validation	CREATE INDEX CONCURRENTLY or REINDEX CONCURRENTLY is waiting for transactions with write locks that can potentially write into the table to finish. This phase is skipped when not in concurrent mode. Columns lockers_total, lockers_done and current_locker_pid contain the progress information for this phase.
index validation: scanning index	CREATE INDEX CONCURRENTLY is scanning the index searching for tuples that need to be validated. This phase is skipped when not in concurrent mode. Columns blocks_total (set to the total size of the index) and blocks_done contain the progress information for this phase.
index validation: sorting tuples	CREATE INDEX CONCURRENTLY is sorting the output of the index scanning phase.
index validation: scanning table	CREATE INDEX CONCURRENTLY is scanning the table to validate the index tuples collected in the previous two phases. This phase is skipped when not in concurrent mode. Columns blocks_total (set to the total size of the table) and blocks_done contain the progress information for this phase.
waiting for old snapshots	CREATE INDEX CONCURRENTLY or REINDEX CONCURRENTLY is waiting for transactions that can potentially see the table to release their snapshots. This phase is skipped when not in concurrent mode. Columns lockers_total, lockers_done and current_locker_pid contain the progress information for this phase.
waiting for readers before marking dead	REINDEX CONCURRENTLY is waiting for transactions with read locks on the table to finish, before marking the old index dead. This phase is skipped when not in concurrent mode. Columns lockers_total, lockers_done and current_locker_pid contain the progress information for this phase.
waiting for readers before dropping	REINDEX CONCURRENTLY is waiting for transactions with read locks on the table to finish, before dropping the old index. This phase is skipped when not in concurrent mode. Columns lockers_total, lockers_done and current_locker_pid contain the progress information for this phase.

27.4.3. VACUUM Progress Reporting

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 for VACUUM FULL commands is reported via pg_stat_progress_cluster because both VACUUM FULL and CLUSTER rewrite the table, while regular VACUUM only modifies it in place. See Section 27.4.4.

Table 27.36. pg_stat_progress_vacuum View

Column Type Description
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 Table 27.37.
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.

Table 27.37. VACUUM Phases

Phase	Description
initializing	VACUUM is preparing to begin scanning the heap. This phase is expected to be very brief.
scanning heap	VACUUM is currently scanning the heap. It will prune and defragment each page if required, and possibly perform freezing activity. The heap_blks_scanned column can be used to monitor the progress of the scan.
vacuuming indexes	VACUUM is currently vacuuming the indexes. If a table has any indexes, this will happen at least once per vacuum, after the heap has been completely scanned. It may happen multiple times per vacuum if maintenance_work_mem is insufficient to store the number of dead tuples found.
vacuuming heap	VACUUM is currently vacuuming the heap. Vacuuming the heap is distinct from scanning the heap, and occurs after each instance of vacuuming indexes. If heap_blks_scanned is less than heap_blks_total, the system will return to scanning the heap after this phase is completed; otherwise, it will begin cleaning up indexes after this phase is completed.
cleaning up indexes	VACUUM is currently cleaning up indexes. This occurs after the heap has been completely scanned and all vacuuming of the indexes and the heap has been completed.
truncating heap	VACUUM is currently truncating the heap so as to return empty pages at the end of the relation to the operating system. This occurs after cleaning up indexes.
performing final cleanup	VACUUM is performing final cleanup. During this phase, VACUUM will vacuum the free space map, update statistics in pg_class, and report statistics to the statistics collector. When this phase is completed, VACUUM will end.

27.4.4. CLUSTER Progress Reporting

Whenever CLUSTER or VACUUM FULL is running, the pg_stat_progress_cluster view will contain a row for each backend that is currently running either command. The tables below describe the information that will be reported and provide information about how to interpret it.

Table 27.38. pg_stat_progress_cluster View

Column Type Description
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 clustered.
command text The command that is running. Either CLUSTER or VACUUM FULL.
phase text Current processing phase. See Table 27.39.
cluster_index_relid oid If the table is being scanned using an index, this is the OID of the index being used; otherwise, it is zero.
heap_tuples_scanned bigint Number of heap tuples scanned. This counter only advances when the phase is seq scanning heap, index scanning heap or writing new heap.
heap_tuples_written bigint Number of heap tuples written. This counter only advances when the phase is seq scanning heap, index scanning heap or writing new heap.
heap_blks_total bigint Total number of heap blocks in the table. This number is reported as of the beginning of seq scanning heap.
heap_blks_scanned bigint Number of heap blocks scanned. This counter only advances when the phase is seq scanning heap.
index_rebuild_count bigint Number of indexes rebuilt. This counter only advances when the phase is rebuilding index.

Table 27.39. CLUSTER and VACUUM FULL Phases

Phase	Description
initializing	The command is preparing to begin scanning the heap. This phase is expected to be very brief.
seq scanning heap	The command is currently scanning the table using a sequential scan.
index scanning heap	CLUSTER is currently scanning the table using an index scan.
sorting tuples	CLUSTER is currently sorting tuples.
writing new heap	CLUSTER is currently writing the new heap.
swapping relation files	The command is currently swapping newly-built files into place.
rebuilding index	The command is currently rebuilding an index.
performing final cleanup	The command is performing final cleanup. When this phase is completed, CLUSTER or VACUUM FULL will end.

27.4.5. Base Backup Progress Reporting

Whenever an application like pg_basebackup is taking a base backup, the pg_stat_progress_basebackup view will contain a row for each WAL sender process that is currently running the BASE_BACKUP replication command and streaming the backup. The tables below describe the information that will be reported and provide information about how to interpret it.

Table 27.40. pg_stat_progress_basebackup View

Column Type Description
pid integer Process ID of a WAL sender process.
phase text Current processing phase. See Table 27.41.
backup_total bigint Total amount of data that will be streamed. This is estimated and reported as of the beginning of streaming database files phase. Note that this is only an approximation since the database may change during streaming database files phase and WAL log may be included in the backup later. This is always the same value as backup_streamed once the amount of data streamed exceeds the estimated total size. If the estimation is disabled in pg_basebackup (i.e., --no-estimate-size option is specified), this is NULL.
backup_streamed bigint Amount of data streamed. This counter only advances when the phase is streaming database files or transferring wal files.
tablespaces_total bigint Total number of tablespaces that will be streamed.
tablespaces_streamed bigint Number of tablespaces streamed. This counter only advances when the phase is streaming database files.

Table 27.41. Base backup phases

Phase	Description
initializing	The WAL sender process is preparing to begin the backup. This phase is expected to be very brief.
waiting for checkpoint to finish	The WAL sender process is currently performing pg_start_backup to prepare to take a base backup, and waiting for the start-of-backup checkpoint to finish.
estimating backup size	The WAL sender process is currently estimating the total amount of database files that will be streamed as a base backup.
streaming database files	The WAL sender process is currently streaming database files as a base backup.
waiting for wal archiving to finish	The WAL sender process is currently performing pg_stop_backup to finish the backup, and waiting for all the WAL files required for the base backup to be successfully archived. If either --wal-method=none or --wal-method=stream is specified in pg_basebackup, the backup will end when this phase is completed.
transferring wal files	The WAL sender process is currently transferring all WAL logs generated during the backup. This phase occurs after waiting for wal archiving to finish phase if --wal-method=fetch is specified in pg_basebackup. The backup will end when this phase is completed.