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Table 2 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
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