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Postgres FD Implementation
Commit 4fa8bd39 authored by Tom Lane's avatar Tom Lane
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Doc: split up wait_event table. 

The previous design for this table didn't really work in narrow views,
such as PDF output; besides which its reliance on large morerows
values made it a pain to maintain (cf ab3e4fbd, for example).

I experimented with a couple of ways to fix it, but the best and
simplest is to split it up into a separate table for each event
type category.

I also rearranged the event ordering to be strictly alphabetical,
as nobody would ever be able to find entries otherwise.

There is work afoot to revise the set of event names described
in this table, but this commit just changes the layout, not the
contents.

In passing, add a missing entry to pg_locks.locktype,
and cross-reference that to the related wait event list.

Discussion: https://postgr.es/m/6916.1589146280@sss.pgh.pa.us
parent a0427506
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doc/src/sgml/catalogs.sgml
View file @ 4fa8bd39
......@@ -10238,9 +10238,11 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
<literal>tuple</literal>,
<literal>transactionid</literal>,
<literal>virtualxid</literal>,
<literal>speculative token</literal>,
<literal>object</literal>,
<literal>userlock</literal>, or
<literal>advisory</literal>
<literal>advisory</literal>.
(See also <xref linkend="wait-event-lock-table"/>.)
</para></entry>
</row>
......
doc/src/sgml/monitoring.sgml
View file @ 4fa8bd39
......@@ -775,79 +775,7 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</para>
<para>
The type of event for which the backend is waiting, if any;
otherwise NULL. Possible values are:
<itemizedlist>
<listitem>
<para>
<literal>LWLock</literal>: The backend is waiting for a lightweight lock.
Each such lock protects a particular data structure in shared memory.
<literal>wait_event</literal> will contain a name identifying the purpose
of the lightweight lock. (Some locks have specific names; others
are part of a group of locks each with a similar purpose.)
</para>
</listitem>
<listitem>
<para>
<literal>Lock</literal>: The backend is waiting for a heavyweight lock.
Heavyweight locks, also known as lock manager locks or simply locks,
primarily protect SQL-visible objects such as tables. However,
they are also used to ensure mutual exclusion for certain internal
operations such as relation extension. <literal>wait_event</literal> will
identify the type of lock awaited.
</para>
</listitem>
<listitem>
<para>
<literal>BufferPin</literal>: The server process is waiting to access to
a data buffer during a period when no other process can be
examining that buffer. Buffer pin waits can be protracted if
another process holds an open cursor which last read data from the
buffer in question.
</para>
</listitem>
<listitem>
<para>
<literal>Activity</literal>: The server process is idle. This is used by
system processes waiting for activity in their main processing loop.
<literal>wait_event</literal> will identify the specific wait point.
</para>
</listitem>
<listitem>
<para>
<literal>Extension</literal>: The server process is waiting for activity
in an extension module. This category is useful for modules to
track custom waiting points.
</para>
</listitem>
<listitem>
<para>
<literal>Client</literal>: The server process is waiting for some activity
on a socket from user applications, and that the server expects
something to happen that is independent from its internal processes.
<literal>wait_event</literal> will identify the specific wait point.
</para>
</listitem>
<listitem>
<para>
<literal>IPC</literal>: The server process is waiting for some activity
from another process in the server. <literal>wait_event</literal> will
identify the specific wait point.
</para>
</listitem>
<listitem>
<para>
<literal>Timeout</literal>: The server process is waiting for a timeout
to expire. <literal>wait_event</literal> will identify the specific wait
point.
</para>
</listitem>
<listitem>
<para>
<literal>IO</literal>: The server process is waiting for a IO to complete.
<literal>wait_event</literal> will identify the specific wait point.
</para>
</listitem>
</itemizedlist>
otherwise NULL. See <xref linkend="wait-event-table"/>.
</para></entry>
</row>
......@@ -857,7 +785,8 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</para>
<para>
Wait event name if backend is currently waiting, otherwise NULL.
See <xref linkend="wait-event-table"/> for details.
See <xref linkend="wait-event-activity-table"/> through
<xref linkend="wait-event-timeout-table"/>.
</para></entry>
</row>
......@@ -978,447 +907,600 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</note>
<table id="wait-event-table">
<title><structname>wait_event</structname> Description</title>
<tgroup cols="3">
<title>Wait Event Types</title>
<tgroup cols="2">
<thead>
<row>
<entry>Wait Event Type</entry>
<entry>Wait Event Name</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry morerows="64"><literal>LWLock</literal></entry>
<entry><literal>ShmemIndexLock</literal></entry>
<entry>Waiting to find or allocate space in shared memory.</entry>
<entry><literal>Activity</literal></entry>
<entry>The server process is idle. This is used by
system processes waiting for activity in their main processing loop.
<literal>wait_event</literal> will identify the specific wait point.
See <xref linkend="wait-event-activity-table"/>.
</entry>
</row>
<row>
<entry><literal>OidGenLock</literal></entry>
<entry>Waiting to allocate or assign an OID.</entry>
<entry><literal>BufferPin</literal></entry>
<entry>The server process is waiting to access to
a data buffer during a period when no other process can be
examining that buffer. Buffer pin waits can be protracted if
another process holds an open cursor which last read data from the
buffer in question. See <xref linkend="wait-event-bufferpin-table"/>.
</entry>
</row>
<row>
<entry><literal>XidGenLock</literal></entry>
<entry>Waiting to allocate or assign a transaction id.</entry>
<entry><literal>Client</literal></entry>
<entry>The server process is waiting for some activity
on a socket from user applications, and that the server expects
something to happen that is independent from its internal processes.
<literal>wait_event</literal> will identify the specific wait point.
See <xref linkend="wait-event-client-table"/>.
</entry>
</row>
<row>
<entry><literal>ProcArrayLock</literal></entry>
<entry>Waiting to get a snapshot or clearing a transaction id at
transaction end.</entry>
<entry><literal>Extension</literal></entry>
<entry>The server process is waiting for activity
in an extension module. This category is useful for modules to
track custom waiting points.
See <xref linkend="wait-event-extension-table"/>.
</entry>
</row>
<row>
<entry><literal>SInvalReadLock</literal></entry>
<entry>Waiting to retrieve or remove messages from shared invalidation
queue.</entry>
<entry><literal>IO</literal></entry>
<entry>The server process is waiting for a IO to complete.
<literal>wait_event</literal> will identify the specific wait point.
See <xref linkend="wait-event-io-table"/>.
</entry>
</row>
<row>
<entry><literal>SInvalWriteLock</literal></entry>
<entry>Waiting to add a message in shared invalidation queue.</entry>
<entry><literal>IPC</literal></entry>
<entry>The server process is waiting for some activity
from another process in the server. <literal>wait_event</literal> will
identify the specific wait point.
See <xref linkend="wait-event-ipc-table"/>.
</entry>
</row>
<row>
<entry><literal>WALBufMappingLock</literal></entry>
<entry>Waiting to replace a page in WAL buffers.</entry>
<entry><literal>Lock</literal></entry>
<entry>The backend is waiting for a heavyweight lock.
Heavyweight locks, also known as lock manager locks or simply locks,
primarily protect SQL-visible objects such as tables. However,
they are also used to ensure mutual exclusion for certain internal
operations such as relation extension. <literal>wait_event</literal>
will identify the type of lock awaited.
See <xref linkend="wait-event-lock-table"/>.
</entry>
</row>
<row>
<entry><literal>WALWriteLock</literal></entry>
<entry>Waiting for WAL buffers to be written to disk.</entry>
<entry><literal>LWLock</literal></entry>
<entry> The backend is waiting for a lightweight lock.
Each such lock protects a particular data structure in shared memory.
<literal>wait_event</literal> will contain a name identifying the purpose
of the lightweight lock. (Some locks have specific names; others
are part of a group of locks each with a similar purpose.)
See <xref linkend="wait-event-lwlock-table"/>.
</entry>
</row>
<row>
<entry><literal>ControlFileLock</literal></entry>
<entry>Waiting to read or update the control file or creation of a
new WAL file.</entry>
<entry><literal>Timeout</literal></entry>
<entry>The server process is waiting for a timeout
to expire. <literal>wait_event</literal> will identify the specific wait
point. See <xref linkend="wait-event-timeout-table"/>.
</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-activity-table">
<title>Wait Events of Type <literal>Activity</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>CheckpointLock</literal></entry>
<entry>Waiting to perform checkpoint.</entry>
<entry><literal>Activity</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>CLogControlLock</literal></entry>
<entry>Waiting to read or update transaction status.</entry>
<entry><literal>ArchiverMain</literal></entry>
<entry>Waiting in main loop of the archiver process.</entry>
</row>
<row>
<entry><literal>SubtransControlLock</literal></entry>
<entry>Waiting to read or update sub-transaction information.</entry>
<entry><literal>AutoVacuumMain</literal></entry>
<entry>Waiting in main loop of autovacuum launcher process.</entry>
</row>
<row>
<entry><literal>MultiXactGenLock</literal></entry>
<entry>Waiting to read or update shared multixact state.</entry>
<entry><literal>BgWriterHibernate</literal></entry>
<entry>Waiting in background writer process, hibernating.</entry>
</row>
<row>
<entry><literal>MultiXactOffsetControlLock</literal></entry>
<entry>Waiting to read or update multixact offset mappings.</entry>
<entry><literal>BgWriterMain</literal></entry>
<entry>Waiting in main loop of background writer process background
worker.</entry>
</row>
<row>
<entry><literal>MultiXactMemberControlLock</literal></entry>
<entry>Waiting to read or update multixact member mappings.</entry>
<entry><literal>CheckpointerMain</literal></entry>
<entry>Waiting in main loop of checkpointer process.</entry>
</row>
<row>
<entry><literal>RelCacheInitLock</literal></entry>
<entry>Waiting to read or write relation cache initialization
file.</entry>
<entry><literal>LogicalApplyMain</literal></entry>
<entry>Waiting in main loop of logical apply process.</entry>
</row>
<row>
<entry><literal>CheckpointerCommLock</literal></entry>
<entry>Waiting to manage fsync requests.</entry>
<entry><literal>LogicalLauncherMain</literal></entry>
<entry>Waiting in main loop of logical launcher process.</entry>
</row>
<row>
<entry><literal>TwoPhaseStateLock</literal></entry>
<entry>Waiting to read or update the state of prepared transactions.</entry>
<entry><literal>PgStatMain</literal></entry>
<entry>Waiting in main loop of the statistics collector process.</entry>
</row>
<row>
<entry><literal>TablespaceCreateLock</literal></entry>
<entry>Waiting to create or drop the tablespace.</entry>
<entry><literal>RecoveryWalStream</literal></entry>
<entry>Waiting for WAL from a stream at recovery.</entry>
</row>
<row>
<entry><literal>BtreeVacuumLock</literal></entry>
<entry>Waiting to read or update vacuum-related information for a
B-tree index.</entry>
<entry><literal>SysLoggerMain</literal></entry>
<entry>Waiting in main loop of syslogger process.</entry>
</row>
<row>
<entry><literal>AddinShmemInitLock</literal></entry>
<entry>Waiting to manage space allocation in shared memory.</entry>
<entry><literal>WalReceiverMain</literal></entry>
<entry>Waiting in main loop of WAL receiver process.</entry>
</row>
<row>
<entry><literal>AutovacuumLock</literal></entry>
<entry>Autovacuum worker or launcher waiting to update or
read the current state of autovacuum workers.</entry>
<entry><literal>WalSenderMain</literal></entry>
<entry>Waiting in main loop of WAL sender process.</entry>
</row>
<row>
<entry><literal>AutovacuumScheduleLock</literal></entry>
<entry>Waiting to ensure that the table it has selected for a vacuum
still needs vacuuming.
</entry>
<entry><literal>WalWriterMain</literal></entry>
<entry>Waiting in main loop of WAL writer process.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-bufferpin-table">
<title>Wait Events of Type <literal>BufferPin</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>SyncScanLock</literal></entry>
<entry>Waiting to get the start location of a scan on a table for
synchronized scans.</entry>
<entry><literal>BufferPin</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>RelationMappingLock</literal></entry>
<entry>Waiting to update the relation map file used to store catalog
to filenode mapping.
</entry>
<entry><literal>BufferPin</literal></entry>
<entry>Waiting to acquire a pin on a buffer.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-client-table">
<title>Wait Events of Type <literal>Client</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>AsyncCtlLock</literal></entry>
<entry>Waiting to read or update shared notification state.</entry>
<entry><literal>Client</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>AsyncQueueLock</literal></entry>
<entry>Waiting to read or update notification messages.</entry>
<entry><literal>ClientRead</literal></entry>
<entry>Waiting to read data from the client.</entry>
</row>
<row>
<entry><literal>SerializableXactHashLock</literal></entry>
<entry>Waiting to retrieve or store information about serializable
transactions.</entry>
<entry><literal>ClientWrite</literal></entry>
<entry>Waiting to write data to the client.</entry>
</row>
<row>
<entry><literal>SerializableFinishedListLock</literal></entry>
<entry>Waiting to access the list of finished serializable
transactions.</entry>
<entry><literal>GSSOpenServer</literal></entry>
<entry>Waiting to read data from the client while establishing the GSSAPI
session.</entry>
</row>
<row>
<entry><literal>SerializablePredicateLockListLock</literal></entry>
<entry>Waiting to perform an operation on a list of locks held by
serializable transactions.</entry>
<entry><literal>LibPQWalReceiverConnect</literal></entry>
<entry>Waiting in WAL receiver to establish connection to remote
server.</entry>
</row>
<row>
<entry><literal>OldSerXidLock</literal></entry>
<entry>Waiting to read or record conflicting serializable
transactions.</entry>
<entry><literal>LibPQWalReceiverReceive</literal></entry>
<entry>Waiting in WAL receiver to receive data from remote server.</entry>
</row>
<row>
<entry><literal>SyncRepLock</literal></entry>
<entry>Waiting to read or update information about synchronous
replicas.</entry>
<entry><literal>SSLOpenServer</literal></entry>
<entry>Waiting for SSL while attempting connection.</entry>
</row>
<row>
<entry><literal>BackgroundWorkerLock</literal></entry>
<entry>Waiting to read or update background worker state.</entry>
<entry><literal>WalReceiverWaitStart</literal></entry>
<entry>Waiting for startup process to send initial data for streaming
replication.</entry>
</row>
<row>
<entry><literal>DynamicSharedMemoryControlLock</literal></entry>
<entry>Waiting to read or update dynamic shared memory state.</entry>
<entry><literal>WalSenderWaitForWAL</literal></entry>
<entry>Waiting for WAL to be flushed in WAL sender process.</entry>
</row>
<row>
<entry><literal>AutoFileLock</literal></entry>
<entry>Waiting to update the <filename>postgresql.auto.conf</filename> file.</entry>
<entry><literal>WalSenderWriteData</literal></entry>
<entry>Waiting for any activity when processing replies from WAL
receiver in WAL sender process.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-extension-table">
<title>Wait Events of Type <literal>Extension</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>ReplicationSlotAllocationLock</literal></entry>
<entry>Waiting to allocate or free a replication slot.</entry>
<entry><literal>Extension</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>ReplicationSlotControlLock</literal></entry>
<entry>Waiting to read or update replication slot state.</entry>
<entry><literal>Extension</literal></entry>
<entry>Waiting in an extension.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-io-table">
<title>Wait Events of Type <literal>IO</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>CommitTsControlLock</literal></entry>
<entry>Waiting to read or update transaction commit timestamps.</entry>
<entry><literal>IO</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>CommitTsLock</literal></entry>
<entry>Waiting to read or update the last value set for the
transaction timestamp.</entry>
<entry><literal>BufFileRead</literal></entry>
<entry>Waiting for a read from a buffered file.</entry>
</row>
<row>
<entry><literal>ReplicationOriginLock</literal></entry>
<entry>Waiting to setup, drop or use replication origin.</entry>
<entry><literal>BufFileWrite</literal></entry>
<entry>Waiting for a write to a buffered file.</entry>
</row>
<row>
<entry><literal>MultiXactTruncationLock</literal></entry>
<entry>Waiting to read or truncate multixact information.</entry>
<entry><literal>ControlFileRead</literal></entry>
<entry>Waiting for a read from the control file.</entry>
</row>
<row>
<entry><literal>OldSnapshotTimeMapLock</literal></entry>
<entry>Waiting to read or update old snapshot control information.</entry>
<entry><literal>ControlFileSync</literal></entry>
<entry>Waiting for the control file to reach stable storage.</entry>
</row>
<row>
<entry><literal>LogicalRepWorkerLock</literal></entry>
<entry>Waiting for action on logical replication worker to finish.</entry>
<entry><literal>ControlFileSyncUpdate</literal></entry>
<entry>Waiting for an update to the control file to reach stable
storage.</entry>
</row>
<row>
<entry><literal>CLogTruncationLock</literal></entry>
<entry>Waiting to execute <function>pg_xact_status</function> or update
the oldest transaction id available to it.</entry>
<entry><literal>ControlFileWrite</literal></entry>
<entry>Waiting for a write to the control file.</entry>
</row>
<row>
<entry><literal>clog</literal></entry>
<entry>Waiting for I/O on a clog (transaction status) buffer.</entry>
<entry><literal>ControlFileWriteUpdate</literal></entry>
<entry>Waiting for a write to update the control file.</entry>
</row>
<row>
<entry><literal>commit_timestamp</literal></entry>
<entry>Waiting for I/O on commit timestamp buffer.</entry>
<entry><literal>CopyFileRead</literal></entry>
<entry>Waiting for a read during a file copy operation.</entry>
</row>
<row>
<entry><literal>subtrans</literal></entry>
<entry>Waiting for I/O a subtransaction buffer.</entry>
<entry><literal>CopyFileWrite</literal></entry>
<entry>Waiting for a write during a file copy operation.</entry>
</row>
<row>
<entry><literal>multixact_offset</literal></entry>
<entry>Waiting for I/O on a multixact offset buffer.</entry>
<entry><literal>DSMFillZeroWrite</literal></entry>
<entry>Waiting to write zero bytes to a dynamic shared memory backing
file.</entry>
</row>
<row>
<entry><literal>multixact_member</literal></entry>
<entry>Waiting for I/O on a multixact_member buffer.</entry>
<entry><literal>DataFileExtend</literal></entry>
<entry>Waiting for a relation data file to be extended.</entry>
</row>
<row>
<entry><literal>async</literal></entry>
<entry>Waiting for I/O on an async (notify) buffer.</entry>
<entry><literal>DataFileFlush</literal></entry>
<entry>Waiting for a relation data file to reach stable storage.</entry>
</row>
<row>
<entry><literal>oldserxid</literal></entry>
<entry>Waiting for I/O on an oldserxid buffer.</entry>
<entry><literal>DataFileImmediateSync</literal></entry>
<entry>Waiting for an immediate synchronization of a relation data file to
stable storage.</entry>
</row>
<row>
<entry><literal>wal_insert</literal></entry>
<entry>Waiting to insert WAL into a memory buffer.</entry>
<entry><literal>DataFilePrefetch</literal></entry>
<entry>Waiting for an asynchronous prefetch from a relation data
file.</entry>
</row>
<row>
<entry><literal>buffer_content</literal></entry>
<entry>Waiting to read or write a data page in memory.</entry>
<entry><literal>DataFileRead</literal></entry>
<entry>Waiting for a read from a relation data file.</entry>
</row>
<row>
<entry><literal>buffer_io</literal></entry>
<entry>Waiting for I/O on a data page.</entry>
<entry><literal>DataFileSync</literal></entry>
<entry>Waiting for changes to a relation data file to reach stable storage.</entry>
</row>
<row>
<entry><literal>replication_origin</literal></entry>
<entry>Waiting to read or update the replication progress.</entry>
<entry><literal>DataFileTruncate</literal></entry>
<entry>Waiting for a relation data file to be truncated.</entry>
</row>
<row>
<entry><literal>DataFileWrite</literal></entry>
<entry>Waiting for a write to a relation data file.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirRead</literal></entry>
<entry>Waiting for a read while adding a line to the data directory lock
file.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirSync</literal></entry>
<entry>Waiting for data to reach stable storage while adding a line to the
data directory lock file.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirWrite</literal></entry>
<entry>Waiting for a write while adding a line to the data directory
lock file.</entry>
</row>
<row>
<entry><literal>LockFileCreateRead</literal></entry>
<entry>Waiting to read while creating the data directory lock
file.</entry>
</row>
<row>
<entry><literal>LockFileCreateSync</literal></entry>
<entry>Waiting for data to reach stable storage while creating the data
directory lock file.</entry>
</row>
<row>
<entry><literal>LockFileCreateWrite</literal></entry>
<entry>Waiting for a write while creating the data directory lock
file.</entry>
</row>
<row>
<entry><literal>LockFileReCheckDataDirRead</literal></entry>
<entry>Waiting for a read during recheck of the data directory lock
file.</entry>
</row>
<row>
<entry><literal>LogicalRewriteCheckpointSync</literal></entry>
<entry>Waiting for logical rewrite mappings to reach stable storage
during a checkpoint.</entry>
</row>
<row>
<entry><literal>replication_slot_io</literal></entry>
<entry>Waiting for I/O on a replication slot.</entry>
<entry><literal>LogicalRewriteMappingSync</literal></entry>
<entry>Waiting for mapping data to reach stable storage during a logical
rewrite.</entry>
</row>
<row>
<entry><literal>proc</literal></entry>
<entry>Waiting to read or update the fast-path lock information.</entry>
<entry><literal>LogicalRewriteMappingWrite</literal></entry>
<entry>Waiting for a write of mapping data during a logical
rewrite.</entry>
</row>
<row>
<entry><literal>buffer_mapping</literal></entry>
<entry>Waiting to associate a data block with a buffer in the buffer
pool.</entry>
<entry><literal>LogicalRewriteSync</literal></entry>
<entry>Waiting for logical rewrite mappings to reach stable
storage.</entry>
</row>
<row>
<entry><literal>lock_manager</literal></entry>
<entry>Waiting to add or examine locks for backends, or waiting to
join or exit a locking group (used by parallel query).</entry>
<entry><literal>LogicalRewriteTruncate</literal></entry>
<entry>Waiting for truncate of mapping data during a logical
rewrite.</entry>
</row>
<row>
<entry><literal>predicate_lock_manager</literal></entry>
<entry>Waiting to add or examine predicate lock information.</entry>
<entry><literal>LogicalRewriteWrite</literal></entry>
<entry>Waiting for a write of logical rewrite mappings.</entry>
</row>
<row>
<entry><literal>serializable_xact</literal></entry>
<entry>Waiting to perform an operation on a serializable transaction
in a parallel query.</entry>
<entry><literal>ProcSignalBarrier</literal></entry>
<entry>Waiting for a barrier event to be processed by all
backends.</entry>
</row>
<row>
<entry><literal>parallel_query_dsa</literal></entry>
<entry>Waiting for parallel query dynamic shared memory allocation lock.</entry>
<entry><literal>RelationMapRead</literal></entry>
<entry>Waiting for a read of the relation map file.</entry>
</row>
<row>
<entry><literal>tbm</literal></entry>
<entry>Waiting for TBM shared iterator lock.</entry>
<entry><literal>RelationMapSync</literal></entry>
<entry>Waiting for the relation map file to reach stable storage.</entry>
</row>
<row>
<entry><literal>parallel_append</literal></entry>
<entry>Waiting to choose the next subplan during Parallel Append plan
execution.</entry>
<entry><literal>RelationMapWrite</literal></entry>
<entry>Waiting for a write to the relation map file.</entry>
</row>
<row>
<entry><literal>parallel_hash_join</literal></entry>
<entry>Waiting to allocate or exchange a chunk of memory or update
counters during Parallel Hash plan execution.</entry>
<entry><literal>ReorderBufferRead</literal></entry>
<entry>Waiting for a read during reorder buffer management.</entry>
</row>
<row>
<entry morerows="9"><literal>Lock</literal></entry>
<entry><literal>relation</literal></entry>
<entry>Waiting to acquire a lock on a relation.</entry>
<entry><literal>ReorderBufferWrite</literal></entry>
<entry>Waiting for a write during reorder buffer management.</entry>
</row>
<row>
<entry><literal>extend</literal></entry>
<entry>Waiting to extend a relation.</entry>
<entry><literal>ReorderLogicalMappingRead</literal></entry>
<entry>Waiting for a read of a logical mapping during reorder buffer
management.</entry>
</row>
<row>
<entry><literal>page</literal></entry>
<entry>Waiting to acquire a lock on page of a relation.</entry>
<entry><literal>ReplicationSlotRead</literal></entry>
<entry>Waiting for a read from a replication slot control file.</entry>
</row>
<row>
<entry><literal>tuple</literal></entry>
<entry>Waiting to acquire a lock on a tuple.</entry>
<entry><literal>ReplicationSlotRestoreSync</literal></entry>
<entry>Waiting for a replication slot control file to reach stable storage
while restoring it to memory.</entry>
</row>
<row>
<entry><literal>transactionid</literal></entry>
<entry>Waiting for a transaction to finish.</entry>
<entry><literal>ReplicationSlotSync</literal></entry>
<entry>Waiting for a replication slot control file to reach stable
storage.</entry>
</row>
<row>
<entry><literal>virtualxid</literal></entry>
<entry>Waiting to acquire a virtual xid lock.</entry>
<entry><literal>ReplicationSlotWrite</literal></entry>
<entry>Waiting for a write to a replication slot control file.</entry>
</row>
<row>
<entry><literal>speculative token</literal></entry>
<entry>Waiting to acquire a speculative insertion lock.</entry>
<entry><literal>SLRUFlushSync</literal></entry>
<entry>Waiting for SLRU data to reach stable storage during a checkpoint
or database shutdown.</entry>
</row>
<row>
<entry><literal>object</literal></entry>
<entry>Waiting to acquire a lock on a non-relation database object.</entry>
<entry><literal>SLRURead</literal></entry>
<entry>Waiting for a read of an SLRU page.</entry>
</row>
<row>
<entry><literal>userlock</literal></entry>
<entry>Waiting to acquire a user lock.</entry>
<entry><literal>SLRUSync</literal></entry>
<entry>Waiting for SLRU data to reach stable storage following a page
write.</entry>
</row>
<row>
<entry><literal>advisory</literal></entry>
<entry>Waiting to acquire an advisory user lock.</entry>
<entry><literal>SLRUWrite</literal></entry>
<entry>Waiting for a write of an SLRU page.</entry>
</row>
<row>
<entry><literal>BufferPin</literal></entry>
<entry><literal>BufferPin</literal></entry>
<entry>Waiting to acquire a pin on a buffer.</entry>
<entry><literal>SnapbuildRead</literal></entry>
<entry>Waiting for a read of a serialized historical catalog
snapshot.</entry>
</row>
<row>
<entry morerows="12"><literal>Activity</literal></entry>
<entry><literal>ArchiverMain</literal></entry>
<entry>Waiting in main loop of the archiver process.</entry>
<entry><literal>SnapbuildSync</literal></entry>
<entry>Waiting for a serialized historical catalog snapshot to reach
stable storage.</entry>
</row>
<row>
<entry><literal>AutoVacuumMain</literal></entry>
<entry>Waiting in main loop of autovacuum launcher process.</entry>
<entry><literal>SnapbuildWrite</literal></entry>
<entry>Waiting for a write of a serialized historical catalog
snapshot.</entry>
</row>
<row>
<entry><literal>BgWriterHibernate</literal></entry>
<entry>Waiting in background writer process, hibernating.</entry>
<entry><literal>TimelineHistoryFileSync</literal></entry>
<entry>Waiting for a timeline history file received via streaming
replication to reach stable storage.</entry>
</row>
<row>
<entry><literal>BgWriterMain</literal></entry>
<entry>Waiting in main loop of background writer process background worker.</entry>
<entry><literal>TimelineHistoryFileWrite</literal></entry>
<entry>Waiting for a write of a timeline history file received via
streaming replication.</entry>
</row>
<row>
<entry><literal>CheckpointerMain</literal></entry>
<entry>Waiting in main loop of checkpointer process.</entry>
<entry><literal>TimelineHistoryRead</literal></entry>
<entry>Waiting for a read of a timeline history file.</entry>
</row>
<row>
<entry><literal>LogicalApplyMain</literal></entry>
<entry>Waiting in main loop of logical apply process.</entry>
<entry><literal>TimelineHistorySync</literal></entry>
<entry>Waiting for a newly created timeline history file to reach stable
storage.</entry>
</row>
<row>
<entry><literal>LogicalLauncherMain</literal></entry>
<entry>Waiting in main loop of logical launcher process.</entry>
<entry><literal>TimelineHistoryWrite</literal></entry>
<entry>Waiting for a write of a newly created timeline history
file.</entry>
</row>
<row>
<entry><literal>PgStatMain</literal></entry>
<entry>Waiting in main loop of the statistics collector process.</entry>
<entry><literal>TwophaseFileRead</literal></entry>
<entry>Waiting for a read of a two phase state file.</entry>
</row>
<row>
<entry><literal>RecoveryWalStream</literal></entry>
<entry>Waiting for WAL from a stream at recovery.</entry>
<entry><literal>TwophaseFileSync</literal></entry>
<entry>Waiting for a two phase state file to reach stable storage.</entry>
</row>
<row>
<entry><literal>SysLoggerMain</literal></entry>
<entry>Waiting in main loop of syslogger process.</entry>
<entry><literal>TwophaseFileWrite</literal></entry>
<entry>Waiting for a write of a two phase state file.</entry>
</row>
<row>
<entry><literal>WalReceiverMain</literal></entry>
<entry>Waiting in main loop of WAL receiver process.</entry>
<entry><literal>WALBootstrapSync</literal></entry>
<entry>Waiting for WAL to reach stable storage during
bootstrapping.</entry>
</row>
<row>
<entry><literal>WalSenderMain</literal></entry>
<entry>Waiting in main loop of WAL sender process.</entry>
<entry><literal>WALBootstrapWrite</literal></entry>
<entry>Waiting for a write of a WAL page during bootstrapping.</entry>
</row>
<row>
<entry><literal>WalWriterMain</literal></entry>
<entry>Waiting in main loop of WAL writer process.</entry>
<entry><literal>WALCopyRead</literal></entry>
<entry>Waiting for a read when creating a new WAL segment by copying an
existing one.</entry>
</row>
<row>
<entry morerows="8"><literal>Client</literal></entry>
<entry><literal>ClientRead</literal></entry>
<entry>Waiting to read data from the client.</entry>
<entry><literal>WALCopySync</literal></entry>
<entry>Waiting for a new WAL segment created by copying an existing one to
reach stable storage.</entry>
</row>
<row>
<entry><literal>ClientWrite</literal></entry>
<entry>Waiting to write data to the client.</entry>
<entry><literal>WALCopyWrite</literal></entry>
<entry>Waiting for a write when creating a new WAL segment by copying an
existing one.</entry>
</row>
<row>
<entry><literal>GSSOpenServer</literal></entry>
<entry>Waiting to read data from the client while establishing the GSSAPI session.</entry>
<entry><literal>WALInitSync</literal></entry>
<entry>Waiting for a newly initialized WAL file to reach stable
storage.</entry>
</row>
<row>
<entry><literal>LibPQWalReceiverConnect</literal></entry>
<entry>Waiting in WAL receiver to establish connection to remote server.</entry>
<entry><literal>WALInitWrite</literal></entry>
<entry>Waiting for a write while initializing a new WAL file.</entry>
</row>
<row>
<entry><literal>LibPQWalReceiverReceive</literal></entry>
<entry>Waiting in WAL receiver to receive data from remote server.</entry>
<entry><literal>WALRead</literal></entry>
<entry>Waiting for a read from a WAL file.</entry>
</row>
<row>
<entry><literal>SSLOpenServer</literal></entry>
<entry>Waiting for SSL while attempting connection.</entry>
<entry><literal>WALSenderTimelineHistoryRead</literal></entry>
<entry>Waiting for a read from a timeline history file during walsender
timeline command.</entry>
</row>
<row>
<entry><literal>WalReceiverWaitStart</literal></entry>
<entry>Waiting for startup process to send initial data for streaming replication.</entry>
<entry><literal>WALSync</literal></entry>
<entry>Waiting for a WAL file to reach stable storage.</entry>
</row>
<row>
<entry><literal>WalSenderWaitForWAL</literal></entry>
<entry>Waiting for WAL to be flushed in WAL sender process.</entry>
<entry><literal>WALSyncMethodAssign</literal></entry>
<entry>Waiting for data to reach stable storage while assigning WAL sync
method.</entry>
</row>
<row>
<entry><literal>WalSenderWriteData</literal></entry>
<entry>Waiting for any activity when processing replies from WAL receiver in WAL sender process.</entry>
<entry><literal>WALWrite</literal></entry>
<entry>Waiting for a write to a WAL file.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-ipc-table">
<title>Wait Events of Type <literal>IPC</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>Extension</literal></entry>
<entry><literal>Extension</literal></entry>
<entry>Waiting in an extension.</entry>
<entry><literal>IPC</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry morerows="40"><literal>IPC</literal></entry>
<entry><literal>BackupWaitWalArchive</literal></entry>
<entry>Waiting for WAL files required for the backup to be successfully archived.</entry>
<entry>Waiting for WAL files required for the backup to be successfully
archived.</entry>
</row>
<row>
<entry><literal>BgWorkerShutdown</literal></entry>
......@@ -1430,7 +1512,8 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>BtreePage</literal></entry>
<entry>Waiting for the page number needed to continue a parallel B-tree scan to become available.</entry>
<entry>Waiting for the page number needed to continue a parallel B-tree
scan to become available.</entry>
</row>
<row>
<entry><literal>CheckpointDone</literal></entry>
......@@ -1442,15 +1525,18 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>ClogGroupUpdate</literal></entry>
<entry>Waiting for group leader to update transaction status at transaction end.</entry>
<entry>Waiting for group leader to update transaction status at
transaction end.</entry>
</row>
<row>
<entry><literal>ExecuteGather</literal></entry>
<entry>Waiting for activity from child process when executing <literal>Gather</literal> node.</entry>
<entry>Waiting for activity from child process while
executing <literal>Gather</literal> node.</entry>
</row>
<row>
<entry><literal>Hash/Batch/Allocating</literal></entry>
<entry>Waiting for an elected Parallel Hash participant to allocate a hash table.</entry>
<entry>Waiting for an elected Parallel Hash participant to allocate a hash
table.</entry>
</row>
<row>
<entry><literal>Hash/Batch/Electing</literal></entry>
......@@ -1458,11 +1544,13 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>Hash/Batch/Loading</literal></entry>
<entry>Waiting for other Parallel Hash participants to finish loading a hash table.</entry>
<entry>Waiting for other Parallel Hash participants to finish loading a
hash table.</entry>
</row>
<row>
<entry><literal>Hash/Build/Allocating</literal></entry>
<entry>Waiting for an elected Parallel Hash participant to allocate the initial hash table.</entry>
<entry>Waiting for an elected Parallel Hash participant to allocate the
initial hash table.</entry>
</row>
<row>
<entry><literal>Hash/Build/Electing</literal></entry>
......@@ -1470,15 +1558,18 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>Hash/Build/HashingInner</literal></entry>
<entry>Waiting for other Parallel Hash participants to finish hashing the inner relation.</entry>
<entry>Waiting for other Parallel Hash participants to finish hashing the
inner relation.</entry>
</row>
<row>
<entry><literal>Hash/Build/HashingOuter</literal></entry>
<entry>Waiting for other Parallel Hash participants to finish partitioning the outer relation.</entry>
<entry>Waiting for other Parallel Hash participants to finish partitioning
the outer relation.</entry>
</row>
<row>
<entry><literal>Hash/GrowBatches/Allocating</literal></entry>
<entry>Waiting for an elected Parallel Hash participant to allocate more batches.</entry>
<entry>Waiting for an elected Parallel Hash participant to allocate more
batches.</entry>
</row>
<row>
<entry><literal>Hash/GrowBatches/Deciding</literal></entry>
......@@ -1490,15 +1581,18 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>Hash/GrowBatches/Finishing</literal></entry>
<entry>Waiting for an elected Parallel Hash participant to decide on future batch growth.</entry>
<entry>Waiting for an elected Parallel Hash participant to decide on
future batch growth.</entry>
</row>
<row>
<entry><literal>Hash/GrowBatches/Repartitioning</literal></entry>
<entry>Waiting for other Parallel Hash participants to finishing repartitioning.</entry>
<entry>Waiting for other Parallel Hash participants to finishing
repartitioning.</entry>
</row>
<row>
<entry><literal>Hash/GrowBuckets/Allocating</literal></entry>
<entry>Waiting for an elected Parallel Hash participant to finish allocating more buckets.</entry>
<entry>Waiting for an elected Parallel Hash participant to finish
allocating more buckets.</entry>
</row>
<row>
<entry><literal>Hash/GrowBuckets/Electing</literal></entry>
......@@ -1506,11 +1600,13 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>Hash/GrowBuckets/Reinserting</literal></entry>
<entry>Waiting for other Parallel Hash participants to finish inserting tuples into new buckets.</entry>
<entry>Waiting for other Parallel Hash participants to finish inserting
tuples into new buckets.</entry>
</row>
<row>
<entry><literal>LogicalSyncData</literal></entry>
<entry>Waiting for logical replication remote server to send data for initial table synchronization.</entry>
<entry>Waiting for logical replication remote server to send data for
initial table synchronization.</entry>
</row>
<row>
<entry><literal>LogicalSyncStateChange</literal></entry>
......@@ -1538,7 +1634,8 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>ParallelCreateIndexScan</literal></entry>
<entry>Waiting for parallel <command>CREATE INDEX</command> workers to finish heap scan.</entry>
<entry>Waiting for parallel <command>CREATE INDEX</command> workers to
finish heap scan.</entry>
</row>
<row>
<entry><literal>ParallelFinish</literal></entry>
......@@ -1574,331 +1671,418 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</row>
<row>
<entry><literal>SafeSnapshot</literal></entry>
<entry>Waiting for a snapshot for a <literal>READ ONLY DEFERRABLE</literal> transaction.</entry>
<entry>Waiting for a snapshot for a <literal>READ ONLY DEFERRABLE</literal>
transaction.</entry>
</row>
<row>
<entry><literal>SyncRep</literal></entry>
<entry>Waiting for confirmation from remote server during synchronous replication.</entry>
<entry>Waiting for confirmation from remote server during synchronous
replication.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-lock-table">
<title>Wait Events of Type <literal>Lock</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry morerows="4"><literal>Timeout</literal></entry>
<entry><literal>BaseBackupThrottle</literal></entry>
<entry>Waiting during base backup when throttling activity.</entry>
<entry><literal>Lock</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>PgSleep</literal></entry>
<entry>Waiting in process that called <function>pg_sleep</function>.</entry>
<entry><literal>advisory</literal></entry>
<entry>Waiting to acquire an advisory user lock.</entry>
</row>
<row>
<entry><literal>RecoveryApplyDelay</literal></entry>
<entry>Waiting to apply WAL at recovery because it is delayed.</entry>
<entry><literal>extend</literal></entry>
<entry>Waiting to extend a relation.</entry>
</row>
<row>
<entry><literal>RecoveryRetrieveRetryInterval</literal></entry>
<entry>
Waiting when WAL data is not available from any kind of sources
(<filename>pg_wal</filename>, archive or stream) before trying
again to retrieve WAL data, at recovery.
</entry>
<entry><literal>object</literal></entry>
<entry>Waiting to acquire a lock on a non-relation database object.</entry>
</row>
<row>
<entry><literal>VacuumDelay</literal></entry>
<entry>Waiting in a cost-based vacuum delay point.</entry>
<entry><literal>page</literal></entry>
<entry>Waiting to acquire a lock on page of a relation.</entry>
</row>
<row>
<entry morerows="68"><literal>IO</literal></entry>
<entry><literal>BufFileRead</literal></entry>
<entry>Waiting for a read from a buffered file.</entry>
<entry><literal>relation</literal></entry>
<entry>Waiting to acquire a lock on a relation.</entry>
</row>
<row>
<entry><literal>BufFileWrite</literal></entry>
<entry>Waiting for a write to a buffered file.</entry>
<entry><literal>speculative token</literal></entry>
<entry>Waiting to acquire a speculative insertion lock.</entry>
</row>
<row>
<entry><literal>ControlFileRead</literal></entry>
<entry>Waiting for a read from the control file.</entry>
<entry><literal>transactionid</literal></entry>
<entry>Waiting for a transaction to finish.</entry>
</row>
<row>
<entry><literal>ControlFileSync</literal></entry>
<entry>Waiting for the control file to reach stable storage.</entry>
<entry><literal>tuple</literal></entry>
<entry>Waiting to acquire a lock on a tuple.</entry>
</row>
<row>
<entry><literal>ControlFileSyncUpdate</literal></entry>
<entry>Waiting for an update to the control file to reach stable storage.</entry>
<entry><literal>userlock</literal></entry>
<entry>Waiting to acquire a user lock.</entry>
</row>
<row>
<entry><literal>virtualxid</literal></entry>
<entry>Waiting to acquire a virtual xid lock.</entry>
</row>
</tbody>
</tgroup>
</table>
<table id="wait-event-lwlock-table">
<title>Wait Events of Type <literal>LWLock</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>LWLock</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>AddinShmemInitLock</literal></entry>
<entry>Waiting to manage space allocation in shared memory.</entry>
</row>
<row>
<entry><literal>AsyncCtlLock</literal></entry>
<entry>Waiting to read or update shared notification state.</entry>
</row>
<row>
<entry><literal>AsyncQueueLock</literal></entry>
<entry>Waiting to read or update notification messages.</entry>
</row>
<row>
<entry><literal>AutoFileLock</literal></entry>
<entry>Waiting to update the <filename>postgresql.auto.conf</filename> file.</entry>
</row>
<row>
<entry><literal>AutovacuumLock</literal></entry>
<entry>Autovacuum worker or launcher waiting to update or
read the current state of autovacuum workers.</entry>
</row>
<row>
<entry><literal>AutovacuumScheduleLock</literal></entry>
<entry>Waiting to ensure that the table selected for a vacuum
still needs vacuuming.</entry>
</row>
<row>
<entry><literal>BackgroundWorkerLock</literal></entry>
<entry>Waiting to read or update background worker state.</entry>
</row>
<row>
<entry><literal>ControlFileWrite</literal></entry>
<entry>Waiting for a write to the control file.</entry>
<entry><literal>BtreeVacuumLock</literal></entry>
<entry>Waiting to read or update vacuum-related information for a
B-tree index.</entry>
</row>
<row>
<entry><literal>ControlFileWriteUpdate</literal></entry>
<entry>Waiting for a write to update the control file.</entry>
<entry><literal>CLogControlLock</literal></entry>
<entry>Waiting to read or update transaction status.</entry>
</row>
<row>
<entry><literal>CopyFileRead</literal></entry>
<entry>Waiting for a read during a file copy operation.</entry>
<entry><literal>CLogTruncationLock</literal></entry>
<entry>Waiting to execute <function>pg_xact_status</function> or update
the oldest transaction id available to it.</entry>
</row>
<row>
<entry><literal>CopyFileWrite</literal></entry>
<entry>Waiting for a write during a file copy operation.</entry>
<entry><literal>CheckpointLock</literal></entry>
<entry>Waiting to perform checkpoint.</entry>
</row>
<row>
<entry><literal>DataFileExtend</literal></entry>
<entry>Waiting for a relation data file to be extended.</entry>
<entry><literal>CheckpointerCommLock</literal></entry>
<entry>Waiting to manage fsync requests.</entry>
</row>
<row>
<entry><literal>DataFileFlush</literal></entry>
<entry>Waiting for a relation data file to reach stable storage.</entry>
<entry><literal>CommitTsControlLock</literal></entry>
<entry>Waiting to read or update transaction commit timestamps.</entry>
</row>
<row>
<entry><literal>DataFileImmediateSync</literal></entry>
<entry>Waiting for an immediate synchronization of a relation data file to stable storage.</entry>
<entry><literal>CommitTsLock</literal></entry>
<entry>Waiting to read or update the last value set for the
transaction timestamp.</entry>
</row>
<row>
<entry><literal>DataFilePrefetch</literal></entry>
<entry>Waiting for an asynchronous prefetch from a relation data file.</entry>
<entry><literal>ControlFileLock</literal></entry>
<entry>Waiting to read or update the control file or creation of a
new WAL file.</entry>
</row>
<row>
<entry><literal>DataFileRead</literal></entry>
<entry>Waiting for a read from a relation data file.</entry>
<entry><literal>DynamicSharedMemoryControlLock</literal></entry>
<entry>Waiting to read or update dynamic shared memory state.</entry>
</row>
<row>
<entry><literal>DataFileSync</literal></entry>
<entry>Waiting for changes to a relation data file to reach stable storage.</entry>
<entry><literal>LogicalRepWorkerLock</literal></entry>
<entry>Waiting for action on logical replication worker to finish.</entry>
</row>
<row>
<entry><literal>DataFileTruncate</literal></entry>
<entry>Waiting for a relation data file to be truncated.</entry>
<entry><literal>MultiXactGenLock</literal></entry>
<entry>Waiting to read or update shared multixact state.</entry>
</row>
<row>
<entry><literal>DataFileWrite</literal></entry>
<entry>Waiting for a write to a relation data file.</entry>
<entry><literal>MultiXactMemberControlLock</literal></entry>
<entry>Waiting to read or update multixact member mappings.</entry>
</row>
<row>
<entry><literal>DSMFillZeroWrite</literal></entry>
<entry>Waiting to write zero bytes to a dynamic shared memory backing file.</entry>
<entry><literal>MultiXactOffsetControlLock</literal></entry>
<entry>Waiting to read or update multixact offset mappings.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirRead</literal></entry>
<entry>Waiting for a read while adding a line to the data directory lock file.</entry>
<entry><literal>MultiXactTruncationLock</literal></entry>
<entry>Waiting to read or truncate multixact information.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirSync</literal></entry>
<entry>Waiting for data to reach stable storage while adding a line to the data directory lock file.</entry>
<entry><literal>OidGenLock</literal></entry>
<entry>Waiting to allocate or assign an OID.</entry>
</row>
<row>
<entry><literal>LockFileAddToDataDirWrite</literal></entry>
<entry>Waiting for a write while adding a line to the data directory lock file.</entry>
<entry><literal>OldSerXidLock</literal></entry>
<entry>Waiting to read or record conflicting serializable
transactions.</entry>
</row>
<row>
<entry><literal>LockFileCreateRead</literal></entry>
<entry>Waiting to read while creating the data directory lock file.</entry>
<entry><literal>OldSnapshotTimeMapLock</literal></entry>
<entry>Waiting to read or update old snapshot control information.</entry>
</row>
<row>
<entry><literal>LockFileCreateSync</literal></entry>
<entry>Waiting for data to reach stable storage while creating the data directory lock file.</entry>
<entry><literal>ProcArrayLock</literal></entry>
<entry>Waiting to get a snapshot or clearing a transaction id at
transaction end.</entry>
</row>
<row>
<entry><literal>LockFileCreateWrite</literal></entry>
<entry>Waiting for a write while creating the data directory lock file.</entry>
<entry><literal>RelCacheInitLock</literal></entry>
<entry>Waiting to read or write relation cache initialization file.</entry>
</row>
<row>
<entry><literal>LockFileReCheckDataDirRead</literal></entry>
<entry>Waiting for a read during recheck of the data directory lock file.</entry>
<entry><literal>RelationMappingLock</literal></entry>
<entry>Waiting to update the relation map file used to store catalog
to filenode mapping.</entry>
</row>
<row>
<entry><literal>LogicalRewriteCheckpointSync</literal></entry>
<entry>Waiting for logical rewrite mappings to reach stable storage during a checkpoint.</entry>
<entry><literal>ReplicationOriginLock</literal></entry>
<entry>Waiting to setup, drop or use replication origin.</entry>
</row>
<row>
<entry><literal>LogicalRewriteMappingSync</literal></entry>
<entry>Waiting for mapping data to reach stable storage during a logical rewrite.</entry>
<entry><literal>ReplicationSlotAllocationLock</literal></entry>
<entry>Waiting to allocate or free a replication slot.</entry>
</row>
<row>
<entry><literal>LogicalRewriteMappingWrite</literal></entry>
<entry>Waiting for a write of mapping data during a logical rewrite.</entry>
<entry><literal>ReplicationSlotControlLock</literal></entry>
<entry>Waiting to read or update replication slot state.</entry>
</row>
<row>
<entry><literal>LogicalRewriteSync</literal></entry>
<entry>Waiting for logical rewrite mappings to reach stable storage.</entry>
<entry><literal>SInvalReadLock</literal></entry>
<entry>Waiting to retrieve or remove messages from shared invalidation
queue.</entry>
</row>
<row>
<entry><literal>LogicalRewriteTruncate</literal></entry>
<entry>Waiting for truncate of mapping data during a logical rewrite.</entry>
<entry><literal>SInvalWriteLock</literal></entry>
<entry>Waiting to add a message in shared invalidation queue.</entry>
</row>
<row>
<entry><literal>LogicalRewriteWrite</literal></entry>
<entry>Waiting for a write of logical rewrite mappings.</entry>
<entry><literal>SerializableFinishedListLock</literal></entry>
<entry>Waiting to access the list of finished serializable
transactions.</entry>
</row>
<row>
<entry><literal>ProcSignalBarrier</literal></entry>
<entry>Waiting for a barrier event to be processed by all backends.</entry>
<entry><literal>SerializablePredicateLockListLock</literal></entry>
<entry>Waiting to perform an operation on a list of locks held by
serializable transactions.</entry>
</row>
<row>
<entry><literal>RelationMapRead</literal></entry>
<entry>Waiting for a read of the relation map file.</entry>
<entry><literal>SerializableXactHashLock</literal></entry>
<entry>Waiting to retrieve or store information about serializable
transactions.</entry>
</row>
<row>
<entry><literal>RelationMapSync</literal></entry>
<entry>Waiting for the relation map file to reach stable storage.</entry>
<entry><literal>ShmemIndexLock</literal></entry>
<entry>Waiting to find or allocate space in shared memory.</entry>
</row>
<row>
<entry><literal>RelationMapWrite</literal></entry>
<entry>Waiting for a write to the relation map file.</entry>
<entry><literal>SubtransControlLock</literal></entry>
<entry>Waiting to read or update sub-transaction information.</entry>
</row>
<row>
<entry><literal>ReorderBufferRead</literal></entry>
<entry>Waiting for a read during reorder buffer management.</entry>
<entry><literal>SyncRepLock</literal></entry>
<entry>Waiting to read or update information about synchronous
replicas.</entry>
</row>
<row>
<entry><literal>ReorderBufferWrite</literal></entry>
<entry>Waiting for a write during reorder buffer management.</entry>
<entry><literal>SyncScanLock</literal></entry>
<entry>Waiting to get the start location of a scan on a table for
synchronized scans.</entry>
</row>
<row>
<entry><literal>ReorderLogicalMappingRead</literal></entry>
<entry>Waiting for a read of a logical mapping during reorder buffer management.</entry>
<entry><literal>TablespaceCreateLock</literal></entry>
<entry>Waiting to create or drop the tablespace.</entry>
</row>
<row>
<entry><literal>ReplicationSlotRead</literal></entry>
<entry>Waiting for a read from a replication slot control file.</entry>
<entry><literal>TwoPhaseStateLock</literal></entry>
<entry>Waiting to read or update the state of prepared transactions.</entry>
</row>
<row>
<entry><literal>ReplicationSlotRestoreSync</literal></entry>
<entry>Waiting for a replication slot control file to reach stable storage while restoring it to memory.</entry>
<entry><literal>WALBufMappingLock</literal></entry>
<entry>Waiting to replace a page in WAL buffers.</entry>
</row>
<row>
<entry><literal>ReplicationSlotSync</literal></entry>
<entry>Waiting for a replication slot control file to reach stable storage.</entry>
<entry><literal>WALWriteLock</literal></entry>
<entry>Waiting for WAL buffers to be written to disk.</entry>
</row>
<row>
<entry><literal>ReplicationSlotWrite</literal></entry>
<entry>Waiting for a write to a replication slot control file.</entry>
<entry><literal>XidGenLock</literal></entry>
<entry>Waiting to allocate or assign a transaction id.</entry>
</row>
<row>
<entry><literal>SLRUFlushSync</literal></entry>
<entry>Waiting for SLRU data to reach stable storage during a checkpoint or database shutdown.</entry>
<entry><literal>async</literal></entry>
<entry>Waiting for I/O on an async (notify) buffer.</entry>
</row>
<row>
<entry><literal>SLRURead</literal></entry>
<entry>Waiting for a read of an SLRU page.</entry>
<entry><literal>buffer_content</literal></entry>
<entry>Waiting to read or write a data page in memory.</entry>
</row>
<row>
<entry><literal>SLRUSync</literal></entry>
<entry>Waiting for SLRU data to reach stable storage following a page write.</entry>
<entry><literal>buffer_io</literal></entry>
<entry>Waiting for I/O on a data page.</entry>
</row>
<row>
<entry><literal>SLRUWrite</literal></entry>
<entry>Waiting for a write of an SLRU page.</entry>
<entry><literal>buffer_mapping</literal></entry>
<entry>Waiting to associate a data block with a buffer in the buffer
pool.</entry>
</row>
<row>
<entry><literal>SnapbuildRead</literal></entry>
<entry>Waiting for a read of a serialized historical catalog snapshot.</entry>
<entry><literal>clog</literal></entry>
<entry>Waiting for I/O on a clog (transaction status) buffer.</entry>
</row>
<row>
<entry><literal>SnapbuildSync</literal></entry>
<entry>Waiting for a serialized historical catalog snapshot to reach stable storage.</entry>
<entry><literal>commit_timestamp</literal></entry>
<entry>Waiting for I/O on commit timestamp buffer.</entry>
</row>
<row>
<entry><literal>SnapbuildWrite</literal></entry>
<entry>Waiting for a write of a serialized historical catalog snapshot.</entry>
<entry><literal>lock_manager</literal></entry>
<entry>Waiting to add or examine locks for backends, or waiting to
join or exit a locking group (used by parallel query).</entry>
</row>
<row>
<entry><literal>TimelineHistoryFileSync</literal></entry>
<entry>Waiting for a timeline history file received via streaming replication to reach stable storage.</entry>
<entry><literal>multixact_member</literal></entry>
<entry>Waiting for I/O on a multixact_member buffer.</entry>
</row>
<row>
<entry><literal>TimelineHistoryFileWrite</literal></entry>
<entry>Waiting for a write of a timeline history file received via streaming replication.</entry>
<entry><literal>multixact_offset</literal></entry>
<entry>Waiting for I/O on a multixact offset buffer.</entry>
</row>
<row>
<entry><literal>TimelineHistoryRead</literal></entry>
<entry>Waiting for a read of a timeline history file.</entry>
<entry><literal>oldserxid</literal></entry>
<entry>Waiting for I/O on an oldserxid buffer.</entry>
</row>
<row>
<entry><literal>TimelineHistorySync</literal></entry>
<entry>Waiting for a newly created timeline history file to reach stable storage.</entry>
<entry><literal>parallel_append</literal></entry>
<entry>Waiting to choose the next subplan during Parallel Append plan
execution.</entry>
</row>
<row>
<entry><literal>TimelineHistoryWrite</literal></entry>
<entry>Waiting for a write of a newly created timeline history file.</entry>
<entry><literal>parallel_hash_join</literal></entry>
<entry>Waiting to allocate or exchange a chunk of memory or update
counters during Parallel Hash plan execution.</entry>
</row>
<row>
<entry><literal>TwophaseFileRead</literal></entry>
<entry>Waiting for a read of a two phase state file.</entry>
<entry><literal>parallel_query_dsa</literal></entry>
<entry>Waiting for parallel query dynamic shared memory allocation lock.</entry>
</row>
<row>
<entry><literal>TwophaseFileSync</literal></entry>
<entry>Waiting for a two phase state file to reach stable storage.</entry>
<entry><literal>predicate_lock_manager</literal></entry>
<entry>Waiting to add or examine predicate lock information.</entry>
</row>
<row>
<entry><literal>TwophaseFileWrite</literal></entry>
<entry>Waiting for a write of a two phase state file.</entry>
<entry><literal>proc</literal></entry>
<entry>Waiting to read or update the fast-path lock information.</entry>
</row>
<row>
<entry><literal>WALBootstrapSync</literal></entry>
<entry>Waiting for WAL to reach stable storage during bootstrapping.</entry>
<entry><literal>replication_origin</literal></entry>
<entry>Waiting to read or update the replication progress.</entry>
</row>
<row>
<entry><literal>WALBootstrapWrite</literal></entry>
<entry>Waiting for a write of a WAL page during bootstrapping.</entry>
<entry><literal>replication_slot_io</literal></entry>
<entry>Waiting for I/O on a replication slot.</entry>
</row>
<row>
<entry><literal>WALCopyRead</literal></entry>
<entry>Waiting for a read when creating a new WAL segment by copying an existing one.</entry>
<entry><literal>serializable_xact</literal></entry>
<entry>Waiting to perform an operation on a serializable transaction
in a parallel query.</entry>
</row>
<row>
<entry><literal>WALCopySync</literal></entry>
<entry>Waiting a new WAL segment created by copying an existing one to reach stable storage.</entry>
<entry><literal>subtrans</literal></entry>
<entry>Waiting for I/O on a subtransaction buffer.</entry>
</row>
<row>
<entry><literal>WALCopyWrite</literal></entry>
<entry>Waiting for a write when creating a new WAL segment by copying an existing one.</entry>
<entry><literal>tbm</literal></entry>
<entry>Waiting for TBM shared iterator lock.</entry>
</row>
<row>
<entry><literal>WALInitSync</literal></entry>
<entry>Waiting for a newly initialized WAL file to reach stable storage.</entry>
<entry><literal>wal_insert</literal></entry>
<entry>Waiting to insert WAL into a memory buffer.</entry>
</row>
</tbody>
</tgroup>
</table>
<note>
<para>
Extensions can add <literal>LWLock</literal> types to the list shown in
<xref linkend="wait-event-lwlock-table"/>. In some cases, the name
assigned by an extension will not be available in all server processes;
so a wait event might be reported as
just <quote><literal>extension</literal></quote> rather than the
extension-assigned name.
</para>
</note>
<table id="wait-event-timeout-table">
<title>Wait Events of Type <literal>Timeout</literal></title>
<tgroup cols="2">
<thead>
<row>
<entry><literal>WALInitWrite</literal></entry>
<entry>Waiting for a write while initializing a new WAL file.</entry>
<entry><literal>Timeout</literal> Wait Event</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>WALRead</literal></entry>
<entry>Waiting for a read from a WAL file.</entry>
<entry><literal>BaseBackupThrottle</literal></entry>
<entry>Waiting during base backup when throttling activity.</entry>
</row>
<row>
<entry><literal>WALSenderTimelineHistoryRead</literal></entry>
<entry>Waiting for a read from a timeline history file during walsender timeline command.</entry>
<entry><literal>PgSleep</literal></entry>
<entry>Waiting in process that called <function>pg_sleep</function>.</entry>
</row>
<row>
<entry><literal>WALSync</literal></entry>
<entry>Waiting for a WAL file to reach stable storage.</entry>
<entry><literal>RecoveryApplyDelay</literal></entry>
<entry>Waiting to apply WAL at recovery because it is delayed.</entry>
</row>
<row>
<entry><literal>WALSyncMethodAssign</literal></entry>
<entry>Waiting for data to reach stable storage while assigning WAL sync method.</entry>
<entry><literal>RecoveryRetrieveRetryInterval</literal></entry>
<entry>Waiting when WAL data is not available from any kind of sources
(<filename>pg_wal</filename>, archive or stream) before trying
again to retrieve WAL data, at recovery.</entry>
</row>
<row>
<entry><literal>WALWrite</literal></entry>
<entry>Waiting for a write to a WAL file.</entry>
<entry><literal>VacuumDelay</literal></entry>
<entry>Waiting in a cost-based vacuum delay point.</entry>
</row>
</tbody>
</tgroup>
</table>
<note>
<para>
For tranches registered by extensions, the name is specified by extension
and this will be displayed as <structfield>wait_event</structfield>. It is quite
possible that user has registered the tranche in one of the backends (by
having allocation in dynamic shared memory) in which case other backends
won't have that information, so we display <literal>extension</literal> for such
cases.
</para>
</note>
<para>
Here is an example of how wait events can be viewed
Here is an example of how wait events can be viewed:
<programlisting>
SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event is NOT NULL;
......@@ -4497,7 +4681,8 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS pid,
</para>
<para>
Returns the wait event name if this backend is currently waiting,
otherwise NULL. See <xref linkend="wait-event-table"/> for details.
otherwise NULL. See <xref linkend="wait-event-activity-table"/> through
<xref linkend="wait-event-timeout-table"/>.
</para></entry>
</row>
......
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