Wiki / Wait Events
Wait Events
Compare versionsWhat PostgreSQL is waiting for, with definitions and diagnostic context.
Reading PG 18current·12 versions documented, 9.6 to 20
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Waiting in main loop of archiver process.
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Waiting in main loop of autovacuum launcher process.
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Waiting in background writer process, hibernating.
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Waiting in main loop of background writer process.
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Waiting in main loop of checkpointer process.
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Waiting for checkpointer process to be terminated.
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Waiting in main loop of IO Worker process.
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Waiting in main loop of logical replication apply process.
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Waiting in main loop of logical replication launcher process.
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Waiting in main loop of logical replication parallel apply process.
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Waiting in main loop of statistics collector process.
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Waiting for WAL from a stream at recovery.
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Waiting in main loop of startup process for WAL to arrive, during streaming recovery.
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Waiting in main loop of slot sync worker.
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Waiting for slot sync worker to shut down.
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Waiting in main loop of syslogger process.
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Waiting in main loop of WAL receiver process.
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Waiting in main loop of WAL sender process.
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Waiting in WAL summarizer for more WAL to be generated.
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Waiting in main loop of WAL writer process.
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Waiting to acquire an exclusive pin on a buffer.
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Waiting to acquire an exclusive lock on a buffer.
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Waiting to acquire an exclusive pin on a buffer.
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Waiting to acquire a shared lock on a buffer.
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Waiting to acquire a share exclusive lock on a buffer.
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Waiting to read data from the client.
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Waiting to write data to the client.
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Waiting to read data from the client while establishing a GSSAPI session.
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Waiting in WAL receiver to establish connection to remote server.
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Waiting in WAL receiver to receive data from remote server.
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Waiting for SSL while attempting connection.
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Waiting for WAL to be received and flushed by the physical standby.
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Waiting for WAL to be flushed in WAL sender process.
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Waiting for any activity when processing replies from WAL receiver in WAL sender process.
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Waiting in an extension.
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Waiting for another process to complete IO.
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Waiting for IO execution via io_uring.
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Waiting for IO submission via io_uring.
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Waiting for base backup to read from a file.
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Waiting for data written by a base backup to reach durable storage.
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Waiting for base backup to write to a file.
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Waiting for a read from a buffered file.
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Waiting for a buffered file to be truncated.
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Waiting for a write to a buffered file.
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Waiting for a read from the pg_control file.
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Waiting for the pg_control file to reach durable storage.
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Waiting for an update to the pg_control file to reach durable storage.
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Waiting for a write to the pg_control file.
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Waiting for a write to update the pg_control file.
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Waiting for a file copy operation.
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Waiting for a read during a file copy operation.
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Waiting for a write during a file copy operation.
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Waiting to read data from a pipe, a file or a program during COPY FROM.
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Waiting to write data to a pipe, a file or a program during COPY TO.
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Waiting for a relation data file to be extended.
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Waiting for a relation data file to reach durable storage.
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Waiting for an immediate synchronization of a relation data file to durable storage.
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Waiting for an asynchronous prefetch from a relation data file.
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Waiting for a read from a relation data file.
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Waiting for changes to a relation data file to reach durable storage.
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Waiting for a relation data file to be truncated.
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Waiting for a write to a relation data file.
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Waiting for a dynamic shared memory segment to be allocated.
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Waiting to fill a dynamic shared memory backing file with zeroes.
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Waiting for a read while adding a line to the data directory lock file.
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Waiting for data to reach durable storage while adding a line to the data directory lock file.
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Waiting for a write while adding a line to the data directory lock file.
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Waiting to read while creating the data directory lock file.
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Waiting for data to reach durable storage while creating the data directory lock file.
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Waiting for a write while creating the data directory lock file.
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Waiting for a read during recheck of the data directory lock file.
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Waiting for a read from a logical changes file.
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Waiting for a write to a logical changes file.
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Waiting for logical rewrite mappings to reach durable storage during a checkpoint.
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Waiting for mapping data to reach durable storage during a logical rewrite.
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Waiting for a write of mapping data during a logical rewrite.
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Waiting for logical rewrite mappings to reach durable storage.
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Waiting for truncate of mapping data during a logical rewrite.
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Waiting for a write of logical rewrite mappings.
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Waiting for a read from a logical subxact file.
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Waiting for a write to a logical subxact file.
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Waiting for a read of the relation map file.
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Waiting for durable replacement of a relation map file.
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Waiting for the relation map file to reach durable storage.
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Waiting for a write to the relation map file.
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Waiting for a read during reorder buffer management.
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Waiting for a write during reorder buffer management.
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Waiting for a read of a logical mapping during reorder buffer management.
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Waiting for a read from a replication slot control file.
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Waiting for a replication slot control file to reach durable storage while restoring it to memory.
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Waiting for a replication slot control file to reach durable storage.
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Waiting for a write to a replication slot control file.
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Waiting for SLRU data to reach durable storage during a checkpoint or database shutdown.
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Waiting for a read of an SLRU page.
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Waiting for SLRU data to reach durable storage following a page write.
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Waiting for a write of an SLRU page.
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Waiting for a read of a serialized historical catalog snapshot.
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Waiting for a serialized historical catalog snapshot to reach durable storage.
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Waiting for a write of a serialized historical catalog snapshot.
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Waiting for a timeline history file received via streaming replication to reach durable storage.
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Waiting for a write of a timeline history file received via streaming replication.
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Waiting for a read of a timeline history file.
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Waiting for a newly created timeline history file to reach durable storage.
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Waiting for a write of a newly created timeline history file.
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Waiting for a read of a two phase state file.
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Waiting for a two phase state file to reach durable storage.
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Waiting for a write of a two phase state file.
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Waiting for the version file to reach durable storage while creating a database.
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Waiting for the version file to be written while creating a database.
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Waiting for WAL to reach durable storage during bootstrapping.
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Waiting for a write of a WAL page during bootstrapping.
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Waiting for a read when creating a new WAL segment by copying an existing one.
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Waiting for a new WAL segment created by copying an existing one to reach durable storage.
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Waiting for a write when creating a new WAL segment by copying an existing one.
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Waiting for a newly initialized WAL file to reach durable storage.
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Waiting for a write while initializing a new WAL file.
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Waiting for a read from a WAL file.
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Waiting for a read from a timeline history file during a walsender timeline command.
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Waiting for a read from a WAL summary file.
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Waiting for a write to a WAL summary file.
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Waiting for a WAL file to reach durable storage.
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Waiting for data to reach durable storage while assigning a new WAL sync method.
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Waiting for a write to a WAL file.
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Waiting for subplan nodes of an Append plan node to be ready.
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Waiting for archive_cleanup_command to complete.
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Waiting for archive_command to complete.
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Waiting for the termination of another backend.
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Waiting for WAL files required for a backup to be successfully archived.
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Waiting for background worker to shut down.
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Waiting for background worker to start up.
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Waiting for the page number needed to continue a parallel B-tree scan to become available.
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Waiting for buffer I/O to complete.
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Waiting for a backend that blocks a checkpoint from completing.
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Waiting for a backend that blocks a checkpoint from starting.
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Waiting for a checkpoint to complete.
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Waiting for a checkpoint to start.
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Waiting for data checksums enabling to start.
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Waiting for temporary tables to be dropped for data checksums to be enabled.
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Waiting for activity from a child process while executing a Gather plan node.
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Waiting for an elected Parallel Hash participant to allocate a hash table.
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Waiting to elect a Parallel Hash participant to allocate a hash table.
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Waiting for other Parallel Hash participants to finish loading a hash table.
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Waiting for an elected Parallel Hash participant to allocate the initial hash table.
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Waiting to elect a Parallel Hash participant to allocate the initial hash table.
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Waiting for other Parallel Hash participants to finish hashing the inner relation.
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Waiting for other Parallel Hash participants to finish partitioning the outer relation.
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Waiting to elect a Parallel Hash participant to decide on future batch growth.
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Waiting to elect a Parallel Hash participant to allocate more batches.
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Waiting for an elected Parallel Hash participant to decide on future batch growth.
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Waiting for an elected Parallel Hash participant to allocate more batches.
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Waiting for other Parallel Hash participants to finish repartitioning.
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Waiting to elect a Parallel Hash participant to allocate more buckets.
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Waiting for an elected Parallel Hash participant to finish allocating more buckets.
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Waiting for other Parallel Hash participants to finish inserting tuples into new buckets.
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Waiting for a logical replication leader apply process to send data to a parallel apply process.
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Waiting for a logical replication parallel apply process to change state.
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Waiting for a logical replication remote server to send data for initial table synchronization.
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Waiting for a logical replication remote server to change state.
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Waiting for another process to be attached to a shared message queue.
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Waiting to write a protocol message to a shared message queue.
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Waiting to receive bytes from a shared message queue.
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Waiting to send bytes to a shared message queue.
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Waiting for a multixact creation to complete.
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Waiting for parallel bitmap scan to become initialized.
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Waiting for parallel CREATE INDEX workers to finish heap scan.
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Waiting for parallel workers to finish computing.
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Waiting for the group leader to clear the transaction ID at transaction end.
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Waiting for a barrier event to be processed by all backends.
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Waiting for standby promotion.
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Waiting for recovery conflict resolution for a vacuum cleanup.
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Waiting for recovery conflict resolution for dropping a tablespace.
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Waiting for recovery_end_command to complete.
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Waiting for recovery to be resumed.
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Waiting for decoding worker to export a new output file.
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Waiting for a replication origin to become inactive so it can be dropped.
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Waiting for a replication slot to become inactive so it can be dropped.
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Waiting for restore_command to complete.
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Waiting to obtain a valid snapshot for a READ ONLY DEFERRABLE transaction.
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Waiting for confirmation from a remote server during synchronous replication.
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Waiting for WAL flush to reach a target LSN on a primary or standby.
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Waiting for WAL replay to reach a target LSN on a standby.
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Waiting for WAL write to reach a target LSN on a standby.
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Waiting for the WAL receiver to exit.
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Waiting for upstream server WAL flush position to catch up to requested start point.
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Waiting for startup process to send initial data for streaming replication.
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Waiting for a new WAL summary to be generated.
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Waiting for the group leader to update transaction status at transaction end.
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Waiting to manage an extension's space allocation in shared memory.
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Waiting for another process to complete IO via io_uring.
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Waiting to update AIO worker information.
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Waiting to access AIO worker submission queue.
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Waiting to update the postgresql.auto.conf file.
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Waiting to read or update the current state of autovacuum workers.
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Waiting to ensure that a table selected for autovacuum still needs vacuuming.
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Waiting to generate a random number.
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Waiting to read or update background worker state.
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Waiting to read or update vacuum-related information for a B-tree index.
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Waiting to access a data page in memory.
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Waiting to associate a data block with a buffer in the buffer pool.
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Waiting to begin a checkpoint.
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Waiting to manage fsync requests.
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Waiting to read or update the last value set for a transaction commit timestamp.
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Waiting for I/O on a commit timestamp SLRU buffer.
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Waiting to access the commit timestamp SLRU cache.
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Waiting to read or update the pg_control file or create a new WAL file.
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Waiting for data checksums worker.
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Waiting for a data checksum state transition to be written to WAL.
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Waiting to read or update the dynamic shared memory registry.
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Waiting to access dynamic shared memory registry's dynamic shared memory allocator.
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Waiting to access dynamic shared memory registry's shared hash table.
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Waiting to read or update dynamic shared memory allocation information.
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Waiting to read or update information related to injection points.
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Waiting to read or update a process' fast-path lock information.
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Waiting to read or update information about “heavyweight” locks.
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Waiting to read or update logical decoding status information.
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Waiting to access logical replication launcher's dynamic shared memory allocator.
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Waiting to access logical replication launcher's shared hash table.
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Waiting to read or update the state of logical replication workers.
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Waiting to read or update shared multixact state.
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Waiting for I/O on a multixact member SLRU buffer.
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Waiting to access the multixact member SLRU cache.
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Waiting for I/O on a multixact offset SLRU buffer.
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Waiting to access the multixact offset SLRU cache.
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Waiting to read or truncate multixact information.
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Waiting for I/O on a NOTIFY message SLRU buffer.
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Waiting to access the NOTIFY channel hash table.
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Waiting to read or update NOTIFY messages.
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Waiting to update limit on NOTIFY message storage.
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Waiting to access the NOTIFY message SLRU cache.
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Waiting to allocate a new OID.
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Waiting to read or update old snapshot control information.
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Waiting to choose the next subplan during Parallel Append plan execution.
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Waiting to synchronize workers during Parallel B-tree scan plan execution.
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Waiting to synchronize workers during Parallel Hash Join plan execution.
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Waiting for parallel query dynamic shared memory allocation.
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Waiting for parallel vacuum dynamic shared memory allocation.
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Waiting for parallel query dynamic shared memory allocation.
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Waiting to access a parallel query's information about composite types.
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Waiting to access a parallel query's information about type modifiers that identify anonymous record types.
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Waiting to access the list of predicate locks held by the current serializable transaction during a parallel query.
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Waiting for shared memory stats data access.
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Waiting for stats dynamic shared memory allocator access.
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Waiting for stats shared memory hash table access.
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Waiting to access predicate lock information used by serializable transactions.
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Waiting to access the shared per-process data structures (typically, to get a snapshot or report a session's transaction ID).
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Waiting to read or update a pg_filenode.map file (used to track the filenode assignments of certain system catalogs).
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Waiting to read or update a pg_internal.init relation cache initialization file.
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Waiting to create, drop or use a replication origin.
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Waiting to read or update the progress of one replication origin.
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Waiting to allocate or free a replication slot.
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Waiting to read or update replication slot state.
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Waiting for I/O on a replication slot.
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Waiting for I/O on a serializable transaction conflict SLRU buffer.
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Waiting to read or update shared pg_serial state.
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Waiting to access the list of finished serializable transactions.
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Waiting to access the list of predicate locks held by serializable transactions.
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Waiting to read or update information about serializable transactions.
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Waiting to access the serializable transaction conflict SLRU cache.
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Waiting to access a shared TID bitmap during a parallel bitmap index scan.
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Waiting to access a shared tuple store during parallel query.
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Waiting to find or allocate space in shared memory.
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Waiting to retrieve messages from the shared catalog invalidation queue.
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Waiting to add a message to the shared catalog invalidation queue.
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Waiting for I/O on a sub-transaction SLRU buffer.
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Waiting to access the sub-transaction SLRU cache.
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Waiting to read or update information about the state of synchronous replication.
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Waiting to select the starting location of a synchronized table scan.
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Waiting to create or drop a tablespace.
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Waiting to read or update the state of prepared transactions.
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Waiting to read or update custom wait events information.
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Waiting to read or update shared Wait-for-LSN state.
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Waiting to replace a page in WAL buffers.
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Waiting to insert WAL data into a memory buffer.
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Waiting to read or update WAL summarization state.
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Waiting for WAL buffers to be written to disk.
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Waiting to update limits on transaction id and multixact consumption.
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Waiting for I/O on a transaction status SLRU buffer.
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Waiting to access the transaction status SLRU cache.
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Waiting to execute pg_xact_status or update the oldest transaction ID available to it.
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Waiting to allocate a new transaction ID.
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Waiting to acquire an advisory user lock.
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Waiting to acquire a lock on a remote transaction being applied by a logical replication subscriber.
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Waiting to extend a relation.
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Waiting to update pg_database.datfrozenxid and pg_database.datminmxid.
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Waiting to acquire a lock on a non-relation database object.
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Waiting to acquire a lock on a page of a relation.
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Waiting to acquire a lock on a relation.
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Waiting to acquire a speculative insertion lock.
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Waiting for a transaction to finish.
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Waiting to acquire a lock on a tuple.
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Waiting to acquire a user lock.
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Waiting to acquire a virtual transaction ID lock; see Section 67.1.
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Waiting during base backup when throttling activity.
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Waiting between writes while performing a checkpoint.
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Waiting for commit delay before WAL flush.
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Waiting due to a call to pg_sleep or a sibling function.
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Waiting to apply WAL during recovery because of a delay setting.
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Waiting during recovery when WAL data is not available from any source (pg_wal, archive or stream).
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Waiting while sending synchronization requests to the checkpointer, because the request queue is full.
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Waiting while acquiring a contended spinlock.
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Waiting in a cost-based vacuum delay point.
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Waiting to acquire an exclusive lock to truncate off any empty pages at the end of a table vacuumed.
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Waiting after a WAL summarizer error.