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