PG_THREAD_WAIT_STATUS

PG_THREAD_WAIT_STATUS allows you to test the block waiting status about the backend thread and auxiliary thread of the current instance.

**Table 1** PG_THREAD_WAIT_STATUS columns
Name	Type	Description
node_name	text	Current node name.
db_name	text	Database name.
thread_name	text	Thread name.
query_id	bigint	Query ID. It is equivalent to debug_query_id.
tid	bigint	Thread ID of the current thread.
sessionid	bigint	Current session ID.
lwtid	integer	Lightweight thread ID of the current thread.
psessionid	bigint	Parent session ID.
tlevel	integer	Level of the streaming thread.
smpid	integer	Concurrent thread ID.
wait_status	text	Waiting status of the current thread. For details about the waiting status, see Table 2.
wait_event	text	If wait_status is set to acquire lock, acquire lwlock, or wait io, this column describes the lock, lightweight lock, and I/O information, respectively. Otherwise, this column is empty.
locktag	text	Information about the lock that the current thread is waiting to obtain.
lockmode	text	Lock mode that the current thread is waiting to obtain. The values include table-level lock, row-level lock, and page-level lock modes.
block_sessionid	bigint	ID of the session that blocks the current thread from obtaining the lock.
global_sessionid	text	Global session ID.

The waiting states in the wait_status column are as follows.

**Table 2** Waiting states
Value	Description
none	Waiting for no event.
acquire lock	Waiting for locking until the locking succeeds or times out.
acquire lwlock	Waiting for a lightweight lock.
wait io	Waiting for I/O completion.
wait cmd	Waiting for reading network communication packets to complete.
wait pooler get conn	Waiting for pooler to obtain connections.
wait pooler abort conn	Waiting for pooler to terminate connections.
wait pooler clean conn	Waiting for pooler to clear connections.
pooler create conn: [nodename], total N	Waiting for the pooler to set up a connection. The connection is being established with the node specified by nodename, and there are N connections waiting to be set up.
get conn	Obtaining the connection to other nodes.
set cmd: [nodename]	Waiting for running the SET, RESET, TRANSACTION BLOCK LEVEL PARA SET, or SESSION LEVEL PARA SET statement on the connection. The statement is being executed on the node specified by nodename.
cancel query	Canceling the SQL statement that is being executed through the connection.
stop query	Stopping the query that is being executed through the connection.
wait node: [nodename](plevel), total N, [phase]	Waiting for receiving data from a connected node. The thread is waiting for data from the plevel thread of the node specified by nodename. The data of N connections is waiting to be returned. If phase is included, the possible phases are as follows: begin: The transaction is being started. commit: The transaction is being committed. rollback: The transaction is being rolled back.
wait transaction sync: xid	Waiting for synchronizing the transaction specified by xid.
wait wal sync	Waiting for the completion of WAL of synchronization from the specified LSN to the standby instance.
wait data sync	Waiting for the completion of data page synchronization to the standby instance.
wait data sync queue	Waiting for putting the data pages that are in the row-store into the synchronization queue.
flush data: [nodename](plevel), [phase]	Waiting for sending data to the plevel thread of the node specified by nodename. If phase is included, the possible phase is wait quota, indicating that the current communication flow is waiting for the quota value.
stream get conn: [nodename], total N	Waiting for connecting to the consumer object of the node specified by nodename when the stream flow is initialized. There are N consumers waiting to be connected.
wait producer ready: [nodename](plevel), total N	Waiting for each producer to be ready when the stream flow is initialized. The thread is waiting for the procedure of the plevel thread on the nodename node to be ready. There are N producers waiting to be ready.
synchronize quit	Waiting for the threads in the stream thread group to quit when the stream plan ends.
wait stream nodegroup destroy	Waiting for destroying the stream node group when the stream plan ends.
wait active statement	Waiting for job execution under resource and load control.
analyze: [relname], [phase]	Executing ANALYZE for the relname table. If phase is included, the possible phase is autovacuum, indicating that the database automatically enables the AutoVacuum thread to execute ANALYZE.
vacuum: [relname], [phase]	Executing VACUUM for the relname table. If phase is included, the possible phase is autovacuum, indicating that the database automatically enables the AutoVacuum thread to execute VACUUM.
vacuum full: [relname]	Executing VACUUM FULL for the relname table.
create index	Creating an index.
HashJoin - [ build hash \| write file ]	The HashJoin operator is being executed. In this phase, you need to pay attention to the execution time-consuming. build hash: The HashJoin operator is creating a hash table. write file: The HashJoin operator is writing data to disks.
HashAgg - [ build hash \| write file ]	The HashAgg operator is being executed. In this phase, you need to pay attention to the execution time-consuming. build hash: The HashAgg operator is creating a hash table. write file: The HashAgg operator is writing data to disks.
HashSetop - [build hash \| write file ]	The HashSetop operator is being executed. In this phase, you need to pay attention to the execution time-consuming. build hash: The HashSetop operator is creating a hash table. write file: The HashSetop operator is writing data to disks.
Sort \| Sort - [fetch tuple \| write file]	The Sort operator is used for sorting. fetch tuple indicates that the Sort operator is obtaining tuples, and write file indicates that the Sort operator is writing data to disks.
Material \| Material - write file	The Material operator is being executed. write file indicates that the Material operator is writing data to disks.
NestLoop	The NestLoop operator is being executed.
wait memory	Waiting for obtaining the memory.
wait sync consumer next step	Waiting for the consumer to execute the stream operator.
wait sync producer next step	Waiting for the producer to execute the stream operator.
vacuum gpi	Clearing the global partitioned index in the vacuum or autovacuum process.
standby read recovery conflict	The read-only mode of the standby node conflicts with the log replay mode.
standby get snapshot	The standby node obtains the snapshot in read-only mode.
prune table	Waiting for a heap table to clear historical deleted data.
prune index	Waiting for an index to clear historical deleted data.
wait reserve td	Waiting for the Ustore transaction slot allocation.
wait td rollback	Waiting for the Ustore transaction slot to roll back transactions.
wait available td	Waiting for an available transaction slot for Ustore.
wait transaction rollback	Waiting for a transaction to roll back.
wait sync bgworkers	Waiting for an index subthread created in parallel to complete local scanning and sorting.
wait io control	Waiting for job execution under I/O control.
wait gs_sleep	Waiting for the server thread delay.
wait vacuum delay	Waiting for VACUUM delay.
wait seq scan	Execution time of seq scan.
wait index scan	Execution time of index scan.
wait checkpoint start	Start time of the checkpoint phase.
wait checkpoint done	End time of the checkpoint phase.
wait xact start command	Start time of xact.
wait xact commit command	Commit time of xact.
wait for autoextend partition	Waiting for the partitioned table to automatically expand and create partitions.
Accept client conn - Total Time	Total duration from the time when a connection is established to the time when the connection is successful (after the GaussDB receives a connection request from a client).
Accept client conn - ThrdPool - add epoll	Duration from the time when a connection is established to the time when the thread pool adds the session handle to the epoll in thread pool mode (after the GaussDB receives a connection request from a client).
Accept client conn - ThrdPool - wait worker	Duration from the time when the thread pool adds the session handle to the epoll to the time when the working thread pool starts to work in thread pool mode (after the GaussDB receives a connection request from a client).
Accept client conn - ThrdPool - init session	Duration from the time when the working thread pool starts to work to the time the session initialization ends in thread pool mode (after the GaussDB receives a connection request from a client).
Accept client conn - Worker - init proc	(After the GaussDB receives a connection request from a client) Duration from the time when a connection is established to the time when the thread initialization ends in non-thread pool mode.
Accept client conn - Worker - init session	(After the GaussDB receives a connection request from a client) Duration from the time when the thread initialization ends to the time when the session initialization ends in non-thread pool mode.
security audit write pipe	Waiting for an audit log to be written to the pipe.

If wait_status is acquire lwlock, acquire lock, or wait io, there is an event performing I/O operations or waiting for obtaining the corresponding lightweight lock or transaction lock.

The following table describes the corresponding wait events when wait_status is acquire lwlock. If wait_event is extension, the lightweight lock is dynamically allocated and is not monitored.

**Table 3** List of wait events corresponding to lightweight locks
wait_event	Description
ShmemIndexLock	Used to protect the primary index table, a hash table, in shared memory.
OidGenLock	Used to prevent different threads from generating the same OID.
XidGenLock	Used to prevent two transactions from obtaining the same XID.
ProcArrayLock	Used to prevent concurrent access to or concurrent modification on the ProcArray shared array.
SInvalReadLock	Used to prevent concurrent execution with invalid message deletion.
SInvalWriteLock	Used to prevent concurrent execution with invalid message write and deletion.
WALInsertLock	Used to prevent concurrent execution with WAL insertion.
WALWriteLock	Used to prevent concurrent write from a WAL buffer to a disk
ControlFileLock	Used to prevent concurrent read/write or concurrent write/write on the pg_control file.
CheckpointLock	Used to prevent multi-checkpoint concurrent execution.
CLogControlLock	Used to prevent concurrent access to or concurrent modification on the Clog control data structure.
SubtransControlLock	Used to prevent concurrent access to or concurrent modification on the subtransaction control data structure.
MultiXactGenLock	Used to allocate a unique MultiXact ID in serial mode.
MultiXactOffsetControlLock	Used to prevent concurrent read/write or concurrent write/write on pg_multixact/offset.
MultiXactMemberControlLock	Used to prevent concurrent read/write or concurrent write/write on pg_multixact/members.
RelCacheInitLock	Used to add a lock before any operations are performed on the init file when messages are invalid.
CheckpointerCommLock	Used to send file flush requests to a checkpointer. The request structure needs to be inserted to a request queue in serial mode.
TwoPhaseStateLock	Used to prevent concurrent access to or modification on two-phase information sharing arrays.
TablespaceCreateLock	Used to check whether a tablespace exists.
BtreeVacuumLock	Used to prevent VACUUM from clearing pages that are being used by B-tree indexes.
AutovacuumLock	Used to access the autovacuum worker array in serial mode.
AutovacuumScheduleLock	Used to distribute tables requiring VACUUM in serial mode.
AutoanalyzeLock	Used to obtain and release resources related to a task that allows for autoanalyze execution.
SyncScanLock	Used to determine the start position of a relfilenode during heap scanning.
NodeTableLock	Used to protect a shared structure that stores database node information.
PoolerLock	Used to prevent two threads from simultaneously obtaining the same connection from a connection pool.
RelationMappingLock	Used to wait for the mapping file between system catalogs and storage locations to be updated.
Async Ctl	Used to protect asynchronization buffers.
AsyncCtlLock	Used to prevent concurrent access to or concurrent modification on the sharing notification status.
AsyncQueueLock	Used to prevent concurrent access to or concurrent modification on the sharing notification queue.
SerializableXactHashLock	Used to prevent concurrent read/write or concurrent write/write on a sharing structure for serializable transactions.
SerializableFinishedListLock	Used to prevent concurrent read/write or concurrent write/write on a shared linked list for completed serial transactions.
SerializablePredicateLockListLock	Used to protect a linked list of serializable transactions that have locks.
OldSerXidLock	Used to protect a structure that records serializable transactions that have conflicts.
FileStatLock	Used to protect a data structure that stores statistics file information.
SyncRepLock	Used to protect Xlog synchronization information during primary-standby replication.
DataSyncRepLock	Used to protect data page synchronization information during primary-standby replication.
MetaCacheSweepLock	Used to add a lock when metadata is cyclically washed out.
ExtensionConnectorLibLock	Used to add a lock when a specific dynamic library is loaded or uninstalled in ODBC connection initialization scenarios.
SearchServerLibLock	Used to add a lock on the file read operation when a specific dynamic library is initially loaded in GPU-accelerated scenarios.
LsnXlogChkFileLock	Used to serially update the Xlog flush points for primary and standby servers recorded in a specific structure.
ReplicationSlotAllocationLock	Used to add a lock when a primary server allocates streaming replication slots during primary-standby replication.
ReplicationSlotControlLock	Used to prevent concurrent update of replication slot status during primary-standby replication.
ResourcePoolHashLock	Used to prevent concurrent access to or concurrent modification on a resource pool table, a hash table.
WorkloadStatHashLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains SQL requests from the primary node of the database.
WorkloadIoStatHashLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains I/O information of the current database node.
WorkloadCGroupHashLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains Cgroup information.
OBSGetPathLock	Used to prevent concurrent read/write or concurrent write/write on an OBS path.
WorkloadUserInfoLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains user information about load management.
WorkloadRecordLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains requests received by the primary node of the databases during adaptive memory management.
WorkloadIOUtilLock	Used to protect a structure that records iostat and CPU load information.
WorkloadNodeGroupLock	Used to prevent concurrent access to or concurrent modification on a hash table that contains node group information in memory.
JobShmemLock	Used to protect global variables in the shared memory that is periodically read during a scheduled job.
OBSRuntimeLock	Used to obtain environment variables, for example, GAUSSHOME.
LLVMDumpIRLock	Used to export the assembly language for dynamically generating functions.
LLVMParseIRLock	Used to compile and parse a finished IR function from the IR file at the start position of a query.
CriticalCacheBuildLock	Used to load caches from a shared or local cache initialization file.
WaitCountHashLock	Used to protect a shared structure in user statement counting scenarios.
BufMappingLock	Used to protect operations on a table mapped to shared buffer.
LockMgrLock	Used to protect a common lock structure.
PredicateLockMgrLock	Used to protect a lock structure that has serializable transactions.
OperatorRealTLock	Used to prevent concurrent access to or concurrent modification on a global structure that contains real-time data at the operator level.
OperatorHistLock	Used to prevent concurrent access to or concurrent modification on a global structure that contains historical data at the operator level.
SessionRealTLock	Used to prevent concurrent access to or concurrent modification on a global structure that contains real-time data at the query level.
SessionHistLock	Used to prevent concurrent access to or concurrent modification on a global structure that contains historical data at the query level.
BarrierLock	Used to ensure that only one thread is creating a barrier at a time
dummyServerInfoCacheLock	Used to protect a global hash table where the information about database connections is cached.
RPNumberLock	Used by a database node on a computing GaussDB to count the number of threads for a task where plans are being executed.
CBMParseXlogLock	Used to protect the lock used when CBM parses Xlogs.
RelfilenodeReuseLock	Used to prevent the link to a reused column attribute file from being canceled by mistake.
RcvWriteLock	Used to prevent concurrent call of WalDataRcvWrite.
PercentileLock	Used to protect global percentile buffers.
CSNBufMappingLock	Used to protect CSN pages.
UniqueSQLMappingLock	Used to protect a unique SQL hash table.
DelayDDLLock	Used to prevent concurrent DDL operations.
CLOG Ctl	Used to prevent concurrent access to or concurrent modification on the Clog control data structure.
Async Ctl	Used to protect asynchronization buffers.
MultiXactOffset Ctl	Used to protect SLRU buffers of a MultiXact offset.
MultiXactMember Ctl	Used to protect SLRU buffers of a MultiXact member.
OldSerXid SLRU Ctl	Used to protect SLRU buffers of old transaction IDs.
ReplicationSlotLock	Used to protect a replication slot.
PGPROCLock	Used to protect the PGPROC structure.
MetaCacheLock	Used to protect meta caches.
DataCacheLock	Used to protect data caches.
InstrUserLock	Used to protect InstrUserHTAB.
BadBlockStatHashLock	Used to protect the hash table global_bad_block_stat.
BufFreelistLock	Used to ensure the atomicity of free list operations in the shared buffer.
AddinShmemInitLock	Used to protect the initialization of the shared memory object.
AlterPortLock	Used to protect the coordinator node from changing the registration port number.
FdwPartitionCaheLock	Management lock of the buffer of the HDFS partitioned table.
DfsConnectorCacheLock	Management lock of the DFSConnector buffer.
DfsSpaceCacheLock	Management lock of the HDFS tablespace management buffer.
FullBuildXlogCopyStartPtrLock	Used to protect Xlog copy operations in the full build.
DfsUserLoginLock	Used for HDFS user login and authentication.
LogicalReplicationSlotPersistentDataLock	Used to protect data in the replication slot during logical replication.
PgfdwLock	Used by the management instance to establish a connection to the foreign server.
InstanceTimeLock	Used to obtain time information of sessions in an instance.
XlogRemoveSegLock	Used to protect Xlog segment file recycling.
DnUsedSpaceHashLock	Used to update space usage information corresponding to a session.
CsnMinLock	Used to calculate CSNmin.
GPCCommitLock	Used to protect the addition of the global Plan Cache hash table.
GPCClearLock	Used to protect the clearing of the global plan cache hash table.
GPCTimelineLock	Used to protect the timeline check of the global plan cache hash table.
InstanceRealTLock	Used to protect the update of the hash table that stores shared instance statistics.
CLogBufMappingLock	Used to manage the cache of commit logs.
GPCMappingLock	Used to manage the global plan cache.
GPCPrepareMappingLock	Used to manage the global plan cache.
BufferIOLock	Used to protect I/O operations on pages in the shared buffer.
BufferContentLock	Used to protect the read and modification of the page content in the shared buffer.
CSNLOG Ctl	Used for CSN log management.
DoubleWriteLock	Used to manage doublewrite operations.
RowPageReplicationLock	Used to manage data page replication of row-store.
MatviewSeqnoLock	Used to manage the cache of materialized views.
GPRCMappingLock	Used to manage the access and modification operations of the global cache hash table of autonomous transactions.
extension	Other lightweight locks.
wait active statement	Waiting for job execution under resource and load control.
wait memory	Waiting for obtaining the memory.
IOStatLock	Used to concurrently maintain the hash table of resource management I/O statistics.
StartBlockMappingLock	Used by globalstat to obtain information such as startblockarray from pgstat.
PldebugLock	Used to debug stored procedures and perform concurrent maintenance operations.
DataFileIdCacheLock	Used to manage the concurrent access and storage of hash table that stores data file descriptor in the shared memory.
GTMHostInfoLock	Used to protect the concurrent access and storage of shared GTM host information.
TwoPhaseStatePartLock	Used to protect the status information of two-phase transactions (in each partition).
WALBufMappingLock	Used to protect the mapping between WAL buffer page and LSN offset.
UndoZoneLock	Used to protect the concurrent access and storage of undo zone.
RollbackReqHashLock	Used to protect the concurrent access and storage of hash table that stores the rollback request in the shared memory.
UHeapStatLock	Used to protect the concurrent access and storage of Ustore statistics.
WALWritePaxosLock	Used to protect the concurrent sequence of WAL log written to the paxos replication component.
SyncPaxosLock	Used to protect the concurrent access and storage of paxos synchronization queue.
BackgroundWorkerLock	Used to protect the concurrent sequence of background workers.
HadrSwitchoverLock	Used to protect the concurrent sequence of DR switchover.
HashUidLock	Used to protect the concurrent sequence of UID allocation.
ParallelDecodeLock	Used to protect the concurrent sequence of parallel decoding.
XLogMaxCSNLock	Used to protect the maximum volume of CSNs that can be restored locally in DR mode.
DisasterCacheLock	Used to protect the concurrent access and storage of DR cache information in the shared memory.
MaxCSNArrayLock	Used to protect the restoration progress of standby node CSNs in each shard in the shared memory.
RepairBadBlockStatHashLock	Used to protect the concurrent access and storage of the hash table that stores damaged pages in the shared memory.
HypoIndexLock	Used to create, delete and reset the virtual index by the lightweight lock.
XGBoostLibLock	Used by DB4AI to call the XGBoost library.
DropArchiveSlotLock	Used to protect the concurrent sequence of deleting the archive slot.
ProcXactMappingLock	Used to protect the concurrent access and storage of the hash table that stores the mapping information between transaction IDs and threads.
UndoPerZoneLock	Used to protect the concurrent access and storage of each information in undo zone.
UndoSpaceLock	Used to protect the concurrent access and storage of undo space.
SnapshotBlockLock	Used to control the concurrent sequence of snapshot-based backup and disk flushing.
DWSingleFlushFirstLock	Used to control the concurrent sequence of non-segment-pages and single-page doublewrite files.
DWSingleFlushSecondLock	Used to control the concurrent sequence of segment-pages and single-page doublewrite files.
DWSingleFlushSecondBufTagLock	Used to control the concurrent access and storage of metadata of segment-pages and single-page doublewrite files.
RestartPointQueueLock	Used to control the concurrent access and storage of restart point arrays on the standby node.
UnlinkRelHashTblLock	Used to protect the concurrent access and storage of the hash table that restores files to be deleted.
UnlinkRelForkHashTblLock	Used to protect the concurrent access and storage of the hash table that restores the fork files to be deleted.
WALFlushWait	Used to protect the concurrent sequence of log flushing.
WALConsensusWait	Used to protect the transaction commit or log replay which is performed only when the logs are consistent.
WALBufferInitWait	Used to protect the initialization and disk flushing sequence of WAL pages in the shared memory.
WALInitSegment	Used to protect the initialization sequence of WAL segment files.
SegmentHeadPartitionLock	Used to protect the partition lock of metadata in the segment-page header.
PgwrSyncQueueLock	Used to protect the concurrent access and storage of file queues to be flushed to disks.
BarrierHashTblLock	Used to protect the concurrent access and storage of barrier tables in the shared memory.
PageRepairHashTblLock	Used to protect the concurrent access and storage of hash table that stores repaired pages.
FileRepairHashTblLock	Used to protect the concurrent access and storage of the hash table that stores repaired files.
InstrUserLockId	Used to protect the concurrent modification of the hash table that stores user login and logout records.
GsStackLock	Used to ensure that the gs_tack function is not concurrently invoked.
InstrStmtTrackCtlLock	Used to protect the concurrent access and storage of the hash table when full SQL statements are dynamically enabled.
CaptureViewFileHashLock	Used to protect the concurrent access and storage of the hash table when capturing the performance view.
UniqueSqlEvictLock	Used to protect the concurrent access and storage of the hash table when the unique SQL reclamation is enabled.
gtt_shared_ctl	Used to protect concurrent read and write of the hash table that stores the global temporary tables.
AuditIndexFileLock	Used to protect concurrent read and write of index files in the audit log.
TDEKeyCacheLock	Used to control the concurrent read and write of cached data keys encrypted transparently.
BlockchainVersionLock	Used to control the concurrent read and write of global block numbers in the ledger database.
GlobalPrevHashLock	Used to control the concurrent read and write of global verification hash tables in the ledger database.
LWTRANCHE_ACCOUNT_TABLE	Used to control the concurrent read and write of the hash table that stores the account locking status.

The following table describes the corresponding wait events when wait_status is wait io.

**Table 4** List of wait events corresponding to I/Os
wait_event	Description
BufFileRead	Reads data from a temporary file to a specified buffer.
BufFileWrite	Writes the content of a specified buffer to a temporary file.
ControlFileRead	Reads the pg_control file, mainly during database startup, checkpoint execution, and primary/standby verification.
ControlFileSync	Flushes the pg_control file to a disk, mainly during database initialization.
ControlFileSyncUpdate	Flushes the pg_control file to a disk, mainly during database startup, checkpoint execution, and primary/standby verification.
ControlFileWrite	Writes the pg_control file, during database initialization.
ControlFileWriteUpdate	Updates the pg_control file, mainly during database startup, checkpoint execution, and primary/standby verification.
CopyFileRead	Reads a file during file copying.
CopyFileWrite	Writes a file during file copying.
DataFileExtend	Writes a file during file name extension.
DataFileFlush	Flushes a table data file to a disk.
DataFileImmediateSync	Flushes a table data file to a disk immediately.
DataFilePrefetch	Reads a table data file asynchronously.
DataFileRead	Reads a table data file synchronously.
DataFileSync	Flushes table data file modifications to a disk.
DataFileTruncate	Truncates a table data file.
DataFileWrite	Writes a table data file.
LockFileAddToDataDirRead	Reads the postmaster.pid file.
LockFileAddToDataDirSync	Flushes the postmaster.pid file to a disk.
LockFileAddToDataDirWrite	Writes PID information into the postmaster.pid file.
LockFileCreateRead	Reads the LockFile file %s.lock.
LockFileCreateSync	Flushes the LockFile file %s.lock to a disk.
LockFileCreateWRITE	Writes PID information into the LockFile file %s.lock.
RelationMapRead	Reads the mapping file between system catalogs and storage locations.
RelationMapSync	Flushes the mapping file between system catalogs and storage locations to a disk.
RelationMapWrite	Writes the mapping file between system catalogs and storage locations.
ReplicationSlotRead	Reads a streaming replication slot file during a restart.
ReplicationSlotRestoreSync	Flushes a streaming replication slot file to a disk during a restart.
ReplicationSlotSync	Flushes a temporary streaming replication slot file to a disk during checkpoint execution.
ReplicationSlotWrite	Writes a temporary streaming replication slot file during checkpoint execution.
SLRUFlushSync	Flushes the pg_clog, pg_subtrans, and pg_multixact files to a disk, mainly during checkpoint execution and database shutdown.
SLRURead	Reads the pg_clog, pg_subtrans, and pg_multixact files.
SLRUSync	Writes dirty pages into the pg_clog, pg_subtrans, and pg_multixact files, and flushes the files to a disk, mainly during checkpoint execution and database shutdown.
SLRUWrite	Writes the pg_clog, pg_subtrans, and pg_multixact files.
TimelineHistoryRead	Reads the timeline history file during database startup.
TimelineHistorySync	Flushes the timeline history file to a disk during database startup.
TimelineHistoryWrite	Writes to the timeline history file during database startup.
TwophaseFileRead	Reads the pg_twophase file, mainly during two-phase transaction commit and restoration.
TwophaseFileSync	Flushes the pg_twophase file to a disk, mainly during two-phase transaction commit and restoration.
TwophaseFileWrite	Writes the pg_twophase file, mainly during two-phase transaction commit and restoration.
WALBootstrapSync	Flushes an initialized WAL file to a disk during database initialization.
WALBootstrapWrite	Writes an initialized WAL file during database initialization.
WALCopyRead	Reads operation generated when an existing WAL file is read for replication after archiving and restoration.
WALCopySync	Flushes a replicated WAL file to a disk after archiving and restoration.
WALCopyWrite	Writes operation generated when an existing WAL file is read for replication after archiving and restoration.
WALInitSync	Flushes a newly initialized WAL file to a disk during log reclaiming or writing.
WALInitWrite	Initializes a newly created WAL file to 0 during log reclaiming or writing.
WALRead	Reads data from Xlogs during redo operations on two-phase files.
WALSyncMethodAssign	Flushes all open WAL files to a disk.
WALWrite	Writes a WAL file.
WALBufferAccess	Used to access WAL buffer. (To ensure performance, only the number of access times is counted in the kernel code, and the access duration is not counted.)
WALBufferFull	Used to write WAL files when the WAL buffer is full.
DoubleWriteFileRead	Doublewrites and reads a file.
DoubleWriteFileSync	Doublewrites a file and forcibly flushes files to disks.
DoubleWriteFileWrite	Doublewrites a file and writes a file.
PredoProcessPending	Waits for the replay of other records to complete during parallel log replay.
PredoApply	Waits for the replay of other threads to the LSN of the current thread during parallel log replay.
DisableConnectFileRead	Reads the HA lock fragment logic file.
DisableConnectFileSync	Forcibly flushes the HA lock fragment logic file to disks.
DisableConnectFileWrite	Writes the HA lock fragment logic file.
BufHashTableSearch	Searches the hash table in the shared buffer (page eviction may be triggered).
StrategyGetBuffer	Obtains pages from strategy buffer (page eviction may be triggered).
UndoFileExtend	Extends an undo file.
UndoFilePrefetch	Prefetches an undo file.
UndoFileRead	Reads an undo file.
UndoFileWrite	Writes an undo file.
UndoFileSync	Flushes an undo file to a disk.
UndoFileUnlink	Deletes an undo file.
UndoMetaSync	Flushes an undo metadata file to a disk.
DWSingleFlushGetPos	Searches for an available location for a single-page doublewrite file.
DWSingleFlushWrite	Flushes a single-page doublewrite file to a disk.
CkptWaitPageWriterFlush	Waits for page refreshing during full checkpoint execution.
CkptWaitPageWriterSync	Waits for the modified file to be synchronized to the disk before checkpointing.
CkptWaitCommitTransactionFinish	Waits until all transactions are committed before checkpointing.
MPFL_INIT	Initiates max_page_flush_lsn.
MPFL_READ	Reads max_page_flush_lsn.
MPFL_WRITE	Writes max_page_flush_lsn.
OBSList	Traverses an OBS directory.
OBSRead	Reads an OBS object.
OBSWrite	Writes an OBS object.
LOGCTRL_SLEEP	Waits for the standby node to catch up with logs.
ShareStorageWalRead	Reads log files from the shared disk.
ShareStorageWalWrite	Writes log files to the shared disk.
ShareStorageCtlInfoRead	Reads control information from the shared disk.
ShareStorageCtlInfoWrite	Writes control information to the shared disk.
SegFileExtend	Extends segment-page files.
SegReadDisk	Reads segment-page files.
SegWriteDisk	Writes segment-page files.
SegSync	Flushes segment-page files.
SegFileShrink	Collapses segment-page files.

The following table describes the corresponding wait events when wait_status is acquire lock.

**Table 5** List of wait events corresponding to transaction locks
wait_event	Description
relation	Adds a lock to a table.
extend	Adds a lock to a table being scaled out.
partition	Adds a lock to a partitioned table.
partition_seq	Adds a lock to a partition of a partitioned table.
page	Adds a lock to a table page.
tuple	Adds a lock to a tuple on a page.
transactionid	Adds a lock to a transaction ID.
virtualxid	Adds a lock to a virtual transaction ID.
object	Adds a lock to an object.
userlock	Adds a lock to a user.
advisory	Adds an advisory lock.
filenode	Adds a lock to a file name and controls the concurrent sequence of file-level operations.
subtransactionid	Adds a lock to a sub-transaction ID.
tuple_uid	Adds a lock to the hidden column of a tuple UID.