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character_setsManual ChaptersPG1835.7. character_sets The view character_sets identifies the character sets available in the current database. Since PostgreSQL does not support multiple character sets within one database, t…character_sets chdbExtensionsExtensionsExecute isolated chDB queries from PostgreSQL through a helper process chdb clickhouse analytics external-data helper-process chdb AnalyticsAnalytics · Extensions chdb_hookExtensionsExtensionsHeadless hook for COPY and CREATE TABLE over chDB-supported URLs chdb clickhouse copy cloud-storage etl hook chdb Replication and streamsReplication and streams · Extensions Check CallbackManual ChaptersPG1849.2.2. Check Callback The check_configured_cb callback is called to determine whether the module is fully configured and ready to accept WAL files (e.g., its configuration parameters are se…Check Callback Check ConstraintsManual ChaptersPG185.5.1. Check Constraints A check constraint is the most generic constraint type. It allows you to specify that the value in a certain column must satisfy a Boolean (truth-value) expression. …Check Constraints check_accessExtensionsExtensionsFunctions and views to facilitate PostgreSQL object access inspection crunchy_check_access SecuritySecurity · Extensions check_chapmd5_passwordExtensionsExtensionsFunction for verifying CHAP-MD5 authentication responses. password security pg_check_chap_md5 SecuritySecurity · Extensions check_constraint_routine_usageManual ChaptersPG1835.8. check_constraint_routine_usage The view check_constraint_routine_usage identifies routines (functions and procedures) that are used by a check constraint. Only those routines are shown…check_constraint_routine_usage check_constraintsManual ChaptersPG1835.9. check_constraints The view check_constraints contains all check constraints, either defined on a table or on a domain, that are owned by a currently enabled role. (The owner of the tab…check_constraints check_digitsExtensionsExtensionsFunctions to check various identification numbers check digit identification number check_digits Functions and aggregatesFunctions and aggregates · Extensions check_function_bodiesConfigurationReferencecheck_function_bodies Client Connection Defaults 10 This parameter is normally on. When set to off, it disables validation of the function body string during CREATE FUNCTION. Disabling valid…Configuration · Client Connection Defaults check_orapgExtensionsExtensionsValidate Oracle-to-PostgreSQL or EDB migrations by comparing database objects, privileges, attributes, comments, and row counts. migration oracle oracle-fdw validation check_orapg Replicatio…Replication and streams · Extensions check_updatesExtensionsExtensionsTrigger functions to allow/deny certain type of table updates administration perl trigger check_updates AdministrationAdministration · Extensions Checking AssertionsManual ChaptersPG1841.9.2. Checking Assertions The ASSERT statement is a convenient shorthand for inserting debugging checks into PL/pgSQL functions. ASSERT condition [ , message ]; The condition is a Boolean …Checking Assertions CHECKPOINTManual ChaptersPG18CHECKPOINT CHECKPOINT — force a write-ahead log checkpoint Synopsis CHECKPOINTCHECKPOINT CHECKPOINTSQL CommandsReferenceCHECKPOINT Maintenance 10 force a write-ahead log checkpoint A checkpoint is a point in the write-ahead log sequence at which all data files have been updated to reflect the information in t…SQL Commands · Maintenance CheckpointWait EventsReferenceCheckpoint LWLock 10 Waiting to perform checkpoint. 11 12 13 Waiting to begin a checkpoint. 9.6 A brief sample is normal around short internal critical sections. Investigate when the same tr…Wait Events · LWLock checkpoint_completion_targetConfigurationReferencecheckpoint_completion_target Write-Ahead Log 10 Specifies the target of checkpoint completion, as a fraction of total time between checkpoints. The default is 0.5. This parameter can only be…Configuration · Write-Ahead Log checkpoint_flush_afterConfigurationReferencecheckpoint_flush_after Write-Ahead Log 10 Whenever more than checkpoint_flush_after bytes have been written while performing a checkpoint, attempt to force the OS to issue these writes to th…Configuration · Write-Ahead Log checkpoint_segmentsConfigurationReferencecheckpoint_segments Write-Ahead Log 9.0 Maximum number of log file segments between automatic WAL checkpoints (each segment is normally 16 megabytes). The default is three segments. Increasi…Configuration · Write-Ahead Log checkpoint_timeoutConfigurationReferencecheckpoint_timeout Write-Ahead Log 10 Maximum time between automatic WAL checkpoints, in seconds. The valid range is between 30 seconds and one day. The default is five minutes (5min). Incre…Configuration · Write-Ahead Log checkpoint_warningConfigurationReferencecheckpoint_warning Write-Ahead Log 10 Write a message to the server log if checkpoints caused by the filling of checkpoint segment files happen closer together than this many seconds (which …Configuration · Write-Ahead Log CheckpointDelayCompleteWait EventsReferenceCheckpointDelayComplete IPC 17 Waiting for a backend that blocks a checkpoint from completing. 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investigate wh…Wait Events · IPC CheckpointDelayStartWait EventsReferenceCheckpointDelayStart IPC 17 Waiting for a backend that blocks a checkpoint from starting. 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investigate when th…Wait Events · IPC CheckpointDoneWait EventsReferenceCheckpointDone IPC 12 Waiting for a checkpoint to complete. 13 14 15 16 17 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investigate when the same phase pe…Wait Events · IPC CheckpointerCommWait EventsReferenceCheckpointerComm LWLock 10 Waiting to manage fsync requests. 11 12 13 14 15 16 17 18 19 20 9.6 A brief sample is normal around short internal critical sections. Investigate when the same tra…Wait Events · LWLock CheckpointerMainWait EventsReferenceCheckpointerMain Activity 10 Waiting in main loop of checkpointer process. 11 12 13 14 15 16 17 18 19 20 This is normally expected idleness for the matching background process. Investigate o…Wait Events · Activity CheckpointerShutdownWait EventsReferenceCheckpointerShutdown Activity 18 Waiting for checkpointer process to be terminated. 19 20 This is normally expected idleness for the matching background process. Investigate only when queued…Wait Events · Activity CheckpointsManual ChaptersPG1819.5.2. Checkpoints checkpoint_timeout (integer) # Maximum time between automatic WAL checkpoints. If this value is specified without units, it is taken as seconds. The valid range is betwee…Checkpoints CheckpointStartWait EventsReferenceCheckpointStart IPC 12 Waiting for a checkpoint to start. 13 14 15 16 17 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investigate when the same phase pers…Wait Events · IPC CheckpointWriteDelayWait EventsReferenceCheckpointWriteDelay Timeout 14 Waiting between writes while performing a checkpoint. 15 16 17 18 19 20 The wait is normal when the configured policy is intentional and useful work advances …Wait Events · Timeout ChecksumEnableStartconditionWait EventsReferenceChecksumEnableStartcondition IPC 19 Waiting for data checksums enabling to start. 20Wait Events · IPC ChecksumEnableTemptableWaitWait EventsReferenceChecksumEnableTemptableWait IPC 19 Waiting for temporary tables to be dropped for data checksums to be enabled. 20Wait Events · IPC chessExtensionsExtensionsSAN and FEN chess notation data types and functions for PostgreSQL data-type chess Data typesData types · Extensions chess_indexExtensionsExtensionsData types for indexing chess positions. chess indexing chess_index Data typesData types · Extensions chkpassExtensionsExtensionsdata type for auto-encrypted passwords chkpass Data typesData types · Extensions Choosing a ConnectionManual ChaptersPG1834.2.2. Choosing a Connection SQL statements in embedded SQL programs are by default executed on the current connection, that is, the most recently opened one. If an application needs to man…Choosing a Connection chrFunctionsReferencechr String Functions And Operators 10 Character with the given code. For UTF8 the argument is treated as a Unicode code point. For other multibyte encodings the argument must designate an AS…Functions · String Functions And Operators chronoturtleExtensionsExtensionsGit-like branches and append-only row history for tables temporal branching history chrono-turtle Time seriesTime series · Extensions cidrManual ChaptersPG188.9.2. cidr The cidr type holds an IPv4 or IPv6 network specification. Input and output formats follow Classless Internet Domain Routing conventions. The format for specifying networks is ad…cidr