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. The value of this column is the same as that of debug_query_id.
tid	bigint	Current thread ID
sessionid	bigint	Current session ID
lwtid	integer	Lightweight thread ID
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](#Waiting status list).
wait_event	text	If wait_status is acquire lock, acquire lwlock, or wait io, this column describes the lock, lightweight lock, and I/O information, respectively. If wait_status is not any of the three values, this column is empty.
locktag	text	Information about the lock that the current thread is waiting for
lockmode	text	Lock mode that the current thread is waiting to obtain The values include modes in the table-level lock, row-level lock, and page-level lock.
block_sessionid	bigint	ID of the session that blocks the current thread from obtaining the lock
global_sessionid	text	Global session ID

The waiting statuses in the wait_status column are as follows:

Table 2 Waiting status list

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 the pooler to obtain the connection
wait pooler abort conn	Waiting for the pooler to terminate the connection
wait pooler clean conn	Waiting for the 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, 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 or the CU in the column-store into the synchronization queue
flush data: nodename, [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, 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]	The thread is doing ANALYZE to 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]	The thread is doing VACUUM to 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]	The thread is doing VACUUM FULL to the relname table.
create index	An index is being created.
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 - write file	The Sort operator is being executed. 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

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 transaction ID.
ProcArrayLock	Used to prevent concurrent access to or concurrent modification on ProcArray shared arrays.
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 already 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.
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.
CStoreColspaceCacheLock	Used to add a lock when CU space is allocated for a column-store table.
CStoreCUCacheSweepLock	Used to add a lock when CU caches used by a column-store table are cyclically washed out.
MetaCacheSweepLock	Used to add a lock when metadata is cyclically washed out.
ExtensionConnectorLibLock	Adds 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 stream replication slots during primary/standby replication.
ReplicationSlotControlLock	Used to prevent concurrent update of stream 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 side.
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 task.
OBSRuntimeLock	Used to obtain environment variables, for example, GASSHOME.
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 shared-buffer mapping table.
LockMgrLock	Used to protect the information about a common lock structure.
PredicateLockMgrLock	Used to protect the information about 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.
CacheSlotMappingLock	Used to protect global CU cache information.
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 MogDB connections is cached.
RPNumberLock	Used by a database node on a computing MogDB to count the number of threads for a task where plans are being executed.
ClusterRPLock	Used to control concurrent access on MogDB load data maintained in a CCN of MogDB.
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 buffer 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 a user hash table.
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.
CUSlotListLock	Used to control concurrent operations on the slot of the column-store 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.
WorkloadSessionInfoLock	Used to protect the access to the session info memory hash table of the load management module.
InstrWorkloadLock	Used to protect the access to the memory hash table that stores load management statistics.
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.
TsTagsCacheLock	Used to manage the time series tag cache.
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.
extension	Other lightweight locks

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, mainly 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 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	Read 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 stream replication slot file during a restart.
ReplicationSlotRestoreSync	Flushes a stream replication slot file to a disk during a restart.
ReplicationSlotSync	Flushes a temporary stream replication slot file to a disk during checkpoint execution.
ReplicationSlotWrite	Writes a temporary stream 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	Read 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	Write 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	WAL Buffer access (for performance reasons, only the number of accesses are counted in the kernel code, and the access time is not counted).
WALBufferFull	When the WAL Buffer is full, write wal file related processing.
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 playback of other records to complete during parallel log playback.
PredoApply	Waits for other threads to play back logs to the LSN of the current thread during parallel log playback.
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.

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.
cstore_freespace	Adds a lock to idle column-store space.
userlock	Adds a lock to a user.
advisory	Adds an advisory lock.