Search PostgreSQL documentation

LibpqwalreceiverReceiveWait EventsReferenceLibpqwalreceiverReceive Client 10 Waiting in WAL receiver to receive data from remote server. 11 12 13 14 15 16 17 18 19 20 Idle ClientRead sessions are normal connection-pool inventory. Inv…Wait Events · Client Library FunctionsManual ChaptersPG1834.11. Library Functions The libecpg library primarily contains “hidden” functions that are used to implement the functionality expressed by the embedded SQL commands. But there are some fun…Library Functions libuuidExtensionsExtensionsGenerate UUIDs through the system libuuid library function uuid pglibuuid Functions and aggregatesFunctions and aggregates · Extensions libversionExtensionsExtensionsVersion string comparison functions and versiontext type using libversion comparison datatype version postgresql-libversion Data typesData types · Extensions libx509pqExtensionsExtensionsX.509 certificate parsing library for PostgreSQL certificate openssl security x509 libx509pq SecuritySecurity · Extensions LIKEManual ChaptersPG189.7.1. LIKE string LIKE pattern [ESCAPE escape-character] string NOT LIKE pattern [ESCAPE escape-character] The LIKE expression returns true if the string matches the supplied pattern. (As e…LIKE LIKESQL CommandsPG18LIKE Clause While a LIKE clause exists in the SQL standard, many of the options that PostgreSQL accepts for it are not in the standard, and some of the standard's options are not implemented…CREATE TABLE › Compatibility › LIKE Clause LIKE ClauseManual ChaptersPG18LIKE Clause While a LIKE clause exists in the SQL standard, many of the options that PostgreSQL accepts for it are not in the standard, and some of the standard's options are not implemented…LIKE Clause LIMITSQL CommandsPG187.6. LIMIT and OFFSET # LIMIT and OFFSET allow you to retrieve just a portion of the rows that are generated by the rest of the query: SELECT select_list FROM table_expression [ ORDER BY ...…LIMIT and OFFSET LIMIT and OFFSETManual ChaptersPG187.6. LIMIT and OFFSET LIMIT and OFFSET allow you to retrieve just a portion of the rows that are generated by the rest of the query: SELECT select_list FROM table_expression [ ORDER BY ... ]…LIMIT and OFFSET LIMIT and OFFSETManual ChaptersPG18LIMIT and OFFSET The clauses LIMIT and OFFSET are PostgreSQL-specific syntax, also used by MySQL. The SQL:2008 standard has introduced the clauses OFFSET ... FETCH {FIRST|NEXT} ... for the s…LIMIT and OFFSET LIMIT ClauseManual ChaptersPG18LIMIT Clause The LIMIT clause consists of two independent sub-clauses: LIMIT { count | ALL } OFFSET start The parameter count specifies the maximum number of rows to return, while start spec…LIMIT Clause LimitationsManual ChaptersPG18Limitations pg_combinebackup does not recompute page checksums when writing the output directory. Therefore, if any of the backups used for reconstruction were taken with checksums disabled,…Limitations LimitationsManual ChaptersPG18F.6.4. Limitations Only operator classes for int4 and text are included with the module. Only the = operator is supported for search. But it is possible to add support for arrays with union …Limitations LimitationsManual ChaptersPG18F.9.4. Limitations citext's case-folding behavior depends on the LC_CTYPE setting of your database. How it compares values is therefore determined when the database is created. It is not tru…Limitations LimitationsManual ChaptersPG185.12.2.3. Limitations The following limitations apply to partitioned tables: To create a unique or primary key constraint on a partitioned table, the partition keys must not include any expr…Limitations LimitationsManual ChaptersPG1865.4.6. Limitations GIN assumes that indexable operators are strict. This means that extractValue will not be called at all on a null item value (instead, a placeholder index entry is create…Limitations LimitationsManual ChaptersPG18F.21.3. Limitations Dropping a table will still orphan any objects it contains, as the trigger is not executed. You can avoid this by preceding the DROP TABLE with DELETE FROM table. TRUNCAT…Limitations LimitationsManual ChaptersPG18F.40.7. Limitations Data Definition Language (DDL) Permissions Due to implementation restrictions, some DDL operations do not check permissions. Data Control Language (DCL) Permissions Due t…Limitations LimitationsManual ChaptersPG1812.11. Limitations The current limitations of PostgreSQL's text search features are: The length of each lexeme must be less than 2 kilobytes The length of a tsvector (lexemes + positions) mu…Limitations Limitations and Missing FeaturesManual ChaptersPG1843.8.2. Limitations and Missing Features The following features are currently missing from PL/Perl, but they would make welcome contributions. PL/Perl functions cannot call each other direct…Limitations and Missing Features Limitations of Functional DependenciesManual ChaptersPG1814.2.2.1.1. Limitations of Functional Dependencies Functional dependencies are currently only applied when considering simple equality conditions that compare columns to constant values, and…Limitations of Functional Dependencies Limitations of PGP CodeManual ChaptersPG18F.26.3.10. Limitations of PGP Code No support for signing. That also means that it is not checked whether the encryption subkey belongs to the master key. No support for encryption key as ma…Limitations of PGP Code Limits and CompatibilityManual ChaptersPG189.7.3.6. Limits and Compatibility No particular limit is imposed on the length of REs in this implementation. However, programs intended to be highly portable should not employ REs longer th…Limits and Compatibility lineData TypesPG18line infinite line on a planeData Types lineFunctionsReferenceline Geometric Functions And Operators 10 points to line line ( point, point ) → line points to line 11 12 13 Converts two points to the line through them. line ( point, point ) → line Conve…Functions · Geometric Functions And Operators Line SegmentsManual ChaptersPG188.8.3. Line Segments Line segments are represented by pairs of points that are the endpoints of the segment. Values of type lseg are specified using any of the following syntaxes: [ ( x1 , y…Line Segments LinesManual ChaptersPG188.8.2. Lines Lines are represented by the linear equation Ax + By + C = 0, where A and B are not both zero. Values of type line are input and output in the following form: { A, B, C } Altern…Lines Linux Huge PagesManual ChaptersPG1818.4.5. Linux Huge Pages Using huge pages reduces overhead when using large contiguous chunks of memory, as PostgreSQL does, particularly when using large values of shared_buffers. To use th…Linux Huge Pages Linux Memory OvercommitManual ChaptersPG1818.4.4. Linux Memory Overcommit The default virtual memory behavior on Linux is not optimal for PostgreSQL. Because of the way that the kernel implements memory overcommit, the kernel might …Linux Memory Overcommit lispgExtensionsExtensionsLisp-like expression type and evaluator for PostgreSQL language lisp parser lispg Procedural languagesProcedural languages · Extensions LISTENManual ChaptersPG18LISTEN LISTEN — listen for a notification Synopsis LISTEN channelLISTEN LISTENSQL CommandsReferenceLISTEN Sessions & Settings 10 listen for a notification LISTEN channel LISTEN registers the current session as a listener on the notification channel named channel . If the current session i…SQL Commands · Sessions & Settings listen_addressesConfigurationReferencelisten_addresses Connections and Authentication 10 Specifies the TCP/IP address(es) on which the server is to listen for connections from client applications. The value takes the form of a c…Configuration · Connections and Authentication livewireExtensionsExtensionspower delivery modeling electric-grid pgrouting postgis routing livewire GeospatialGeospatial · Extensions ll_to_earthFunctionsPG18ll_to_earth ( float8, float8 ) → earth Returns the location of a point on the surface of the Earth given its latitude (argument 1) and longitude (argument 2) in degrees.earthdistance — calculate great-circle distances › Cube-Based Earth Distances llama_embedExtensionsExtensionsllama.cpp embedding extension for dense and multivector search bm25 hybrid hybrid-search pgvector postgres-extension postgresql rag retrieval turboquant vector-search llama_embed AI and vect…AI and vectors · Extensions lnFunctionsReferenceln Mathematical Functions And Operators 10 natural logarithm ln ( dp or numeric ) → (same as input) natural logarithm 11 12 13 Natural logarithm ln ( numeric ) → numeric Natural logarithm ln…Functions · Mathematical Functions And Operators loExtensionsPG18F.21. lo — manage large objects The lo module provides support for managing Large Objects (also called LOs or BLOBs). This includes a data type lo and a trigger lo_manage. This module is con…lo — manage large objects lo — manage large objectsManual ChaptersPG18F.21. lo — manage large objects The lo module provides support for managing Large Objects (also called LOs or BLOBs). This includes a data type lo and a trigger lo_manage. This module is con…lo — manage large objects