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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 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 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 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 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 cipher-algoManual ChaptersPG18F.26.3.8.1. cipher-algo Which cipher algorithm to use. Values: bf, aes128, aes192, aes256, 3des, cast5 Default: aes128 Applies to: pgp_sym_encrypt, pgp_pub_encryptcipher-algo CirclesManual ChaptersPG188.8.7. Circles Circles are represented by a center point and radius. Values of type circle are specified using any of the following syntaxes: < ( x , y ) , r > ( ( x , y ) , r ) ( x , y ) , …Circles citext — a case-insensitive character string typeManual ChaptersPG18F.9. citext — a case-insensitive character string type The citext module provides a case-insensitive character string type, citext. Essentially, it internally calls lower when comparing valu…citext — a case-insensitive character string type Client ApplicationsManual ChaptersPG18G.1. Client Applications This section covers PostgreSQL client applications in contrib. They can be run from anywhere, independent of where the database server resides. See also PostgreSQL C…Client Applications Client AuthenticationManual ChaptersPG18Chapter 20. Client Authentication When a client application connects to the database server, it specifies which PostgreSQL database user name it wants to connect as, much the same way one lo…Client Authentication Client CertificatesManual ChaptersPG1832.19.2. Client Certificates If the server attempts to verify the identity of the client by requesting the client's leaf certificate, libpq will send the certificate(s) stored in file ~/.pos…Client Certificates Client Connection DefaultsManual ChaptersPG1819.11. Client Connection DefaultsClient Connection Defaults Client Connection ProblemsManual ChaptersPG1818.3.2. Client Connection Problems Although the error conditions possible on the client side are quite varied and application-dependent, a few of them might be directly related to how the se…Client Connection Problems Client InterfacesManual ChaptersPG18Part IV. Client Interfaces This part describes the client programming interfaces distributed with PostgreSQL. Each of these chapters can be read independently. There are many external progra…Client Interfaces Client InterfacesManual ChaptersPG18H.1. Client Interfaces There are only two client interfaces included in the base PostgreSQL distribution: libpq is included because it is the primary C language interface, and because many o…Client Interfaces Client InterfacesManual ChaptersPG1833.3. Client Interfaces This section describes the facilities that PostgreSQL's libpq client interface library provides for accessing large objects. The PostgreSQL large object interface is …Client Interfaces Client Verification of Server CertificatesManual ChaptersPG1832.19.1. Client Verification of Server Certificates By default, PostgreSQL will not perform any verification of the server certificate. This means that it is possible to spoof the server ide…Client Verification of Server Certificates Clock Hardware and Timing AccuracyManual ChaptersPG18Clock Hardware and Timing Accuracy Collecting accurate timing information is normally done on computers using hardware clocks with various levels of accuracy. With some hardware the operatin…Clock Hardware and Timing Accuracy CLOSEManual ChaptersPG1841.7.3.4. CLOSE CLOSE cursor; CLOSE closes the portal underlying an open cursor. This can be used to release resources earlier than end of transaction, or to free up the cursor variable to b…CLOSE CLOSEManual ChaptersPG18CLOSE CLOSE — close a cursor Synopsis CLOSE { name | ALL }CLOSE Closing a ConnectionManual ChaptersPG1834.2.3. Closing a Connection To close a connection, use the following statement: EXEC SQL DISCONNECT [connection]; The connection can be specified in the following ways: connection-name CURR…Closing a Connection Closing a Large Object DescriptorManual ChaptersPG1833.3.10. Closing a Large Object Descriptor A large object descriptor can be closed by calling int lo_close(PGconn *conn, int fd); where fd is a large object descriptor returned by lo_open. O…Closing a Large Object Descriptor CLUSTERManual ChaptersPG18CLUSTER CLUSTER — cluster a table according to an index Synopsis CLUSTER [ ( option [, ...] ) ] [ table_name [ USING index_name ] ] where option can be one of: VERBOSE [ boolean ]CLUSTER CLUSTER Progress ReportingManual ChaptersPG1827.4.2. CLUSTER Progress Reporting Whenever CLUSTER or VACUUM FULL is running, the pg_stat_progress_cluster view will contain a row for each backend that is currently running either command.…CLUSTER Progress Reporting clusterdbManual ChaptersPG18clusterdb clusterdb — cluster a PostgreSQL database Synopsis clusterdb [connection-option...] [option...] [ --table | -t table ] ... [ dbname | -a | --all ]clusterdb COALESCEManual ChaptersPG189.18.2. COALESCE COALESCE(value [, ...]) The COALESCE function returns the first of its arguments that is not null. Null is returned only if all arguments are null. It is often used to subst…COALESCE Code TargetsManual ChaptersPG1817.4.4.1. Code Targets all # Build everything other than documentation backend # Build backend and related modules bin # Build frontend binaries contrib # Build contrib modules pl # Build pr…Code Targets Collation ExpressionsManual ChaptersPG184.2.10. Collation Expressions The COLLATE clause overrides the collation of an expression. It is appended to the expression it applies to: expr COLLATE collation where collation is a possibl…Collation Expressions Collation Level ExamplesManual ChaptersPG1823.2.3.1.1. Collation Level Examples CREATE COLLATION level3 (provider = icu, deterministic = false, locale = 'und-u-ka-shifted-ks-level3'); CREATE COLLATION level4 (provider = icu, determin…Collation Level Examples Collation of PL/pgSQL VariablesManual ChaptersPG1841.3.6. Collation of PL/pgSQL Variables When a PL/pgSQL function has one or more parameters of collatable data types, a collation is identified for each function call depending on the collat…Collation of PL/pgSQL Variables Collation Settings ExamplesManual ChaptersPG1823.2.3.3. Collation Settings Examples CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de-u-co-phonebk'); # German collation with phone book collation type CREATE COLLATIO…Collation Settings Examples Collation Settings for an ICU LocaleManual ChaptersPG1823.2.3.2. Collation Settings for an ICU Locale Table 23.2 shows the available collation settings, which can be used as part of a language tag to customize a collation. Table 23.2. ICU Collat…Collation Settings for an ICU Locale Collation SupportManual ChaptersPG1823.2. Collation Support The collation feature allows specifying the sort order and character classification behavior of data per-column, or even per-operation. This alleviates the restrictio…Collation Support collation_character_set_​applicabilityManual ChaptersPG1835.11. collation_character_set_​applicability The view collation_character_set_applicability identifies which character set the available collations are applicable to. In PostgreSQL, there i…collation_character_set_​applicability collationsManual ChaptersPG1835.10. collations The view collations contains the collations available in the current database. Table 35.8. collations Columns Column Type Description collation_catalog sql_identifier Name …collations Collecting Crash DumpsManual ChaptersPG1817.7.3.1. Collecting Crash Dumps If PostgreSQL on Windows crashes, it has the ability to generate minidumps that can be used to track down the cause for the crash, similar to core dumps on U…Collecting Crash Dumps Collecting Crash DumpsManual ChaptersPG1817.7.5.3. Collecting Crash Dumps If PostgreSQL on Windows crashes, it has the ability to generate minidumps that can be used to track down the cause for the crash, similar to core dumps on U…Collecting Crash Dumps Color SupportManual ChaptersPG18Appendix N. Color Support Most programs in the PostgreSQL package can produce colorized console output. This appendix describes how that is configured.Color Support