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Support Functions for AggregatesManual ChaptersPG1836.12.5. Support Functions for Aggregates A function written in C can detect that it is being called as an aggregate support function by calling AggCheckCallContext, for example: if (AggChec…Support Functions for Aggregates Supported Argument and Result Data TypesManual ChaptersPG1841.1.2. Supported Argument and Result Data Types Functions written in PL/pgSQL can accept as arguments any scalar or array data type supported by the server, and they can return a result of …Supported Argument and Result Data Types Supported Character SetsManual ChaptersPG1823.3.1. Supported Character Sets Table 23.3 shows the character sets available for use in PostgreSQL. Table 23.3. PostgreSQL Character Sets Name Description Language Server? ICU? Bytes/​Char…Supported Character Sets Supported FeaturesManual ChaptersPG18D.1. Supported Features Identifier Core? Description Comment B012 Embedded C B021 Direct SQL B128 Routine language SQL E011 Core Numeric data types E011-01 Core INTEGER and SMALLINT data typ…Supported Features Supported PlatformsManual ChaptersPG1817.6. Supported Platforms A platform (that is, a CPU architecture and operating system combination) is considered supported by the PostgreSQL development community if the code contains provi…Supported Platforms Synchronous ReplicationManual ChaptersPG1826.2.8. Synchronous Replication PostgreSQL streaming replication is asynchronous by default. If the primary server crashes then some transactions that were committed may not have been replic…Synchronous Replication Synchronous Replication Support for Logical DecodingManual ChaptersPG1847.8. Synchronous Replication Support for Logical DecodingSynchronous Replication Support for Logical Decoding Synonym DictionaryManual ChaptersPG1812.6.3. Synonym Dictionary This dictionary template is used to create dictionaries that replace a word with a synonym. Phrases are not supported (use the thesaurus template (Section 12.6.4) …Synonym Dictionary SyntaxManual ChaptersPG18F.10.1. Syntax Table F.1 shows the valid external representations for the cube type. x, y, etc. denote floating-point numbers. Table F.1. Cube External Representations External Syntax Meanin…Syntax SyntaxManual ChaptersPG18F.39.2. Syntax The external representation of an interval is formed using one or two floating-point numbers joined by the range operator (.. or ...). Alternatively, it can be specified as a …Syntax Syntax CheckManual ChaptersPG18J.3.4. Syntax Check Building the documentation can take very long. But there is a method to just check the correct syntax of the documentation files, which only takes a few seconds: doc/src/…Syntax Check System Administration FunctionsManual ChaptersPG189.28. System Administration Functions The functions described in this section are used to control and monitor a PostgreSQL installation.System Administration Functions System Catalog Declaration RulesManual ChaptersPG1868.1. System Catalog Declaration Rules The key part of a catalog header file is a C structure definition describing the layout of each row of the catalog. This begins with a CATALOG macro, w…System Catalog Declaration Rules System Catalog Declarations and Initial ContentsManual ChaptersPG18Chapter 68. System Catalog Declarations and Initial Contents PostgreSQL uses many different system catalogs to keep track of the existence and properties of database objects, such as tables …System Catalog Declarations and Initial Contents System Catalog Information FunctionsManual ChaptersPG189.27.4. System Catalog Information Functions Table 9.76 lists functions that extract information from the system catalogs. Table 9.76. System Catalog Information Functions Function Descripti…System Catalog Information Functions System Catalog Initial DataManual ChaptersPG1868.2. System Catalog Initial Data Each catalog that has any manually-created initial data (some do not) has a corresponding .dat file that contains its initial data in an editable format.System Catalog Initial Data System CatalogsManual ChaptersPG18Chapter 52. System Catalogs The system catalogs are the place where a relational database management system stores schema metadata, such as information about tables and columns, and internal…System Catalogs System Catalogs Related to Logical DecodingManual ChaptersPG1847.5. System Catalogs Related to Logical Decoding The pg_replication_slots view and the pg_stat_replication view provide information about the current state of replication slots and streamin…System Catalogs Related to Logical Decoding System ColumnsManual ChaptersPG185.6. System Columns Every table has several system columns that are implicitly defined by the system. Therefore, these names cannot be used as names of user-defined columns. (Note that these…System Columns System Dependencies on Operator ClassesManual ChaptersPG1836.16.6. System Dependencies on Operator Classes PostgreSQL uses operator classes to infer the properties of operators in more ways than just whether they can be used with indexes. Therefore…System Dependencies on Operator Classes System Information Functions and OperatorsManual ChaptersPG189.27. System Information Functions and Operators The functions described in this section are used to obtain various information about a PostgreSQL installation.System Information Functions and Operators System ViewsManual ChaptersPG18Chapter 53. System Views In addition to the system catalogs, PostgreSQL provides a number of built-in views. Some system views provide convenient access to some commonly used queries on the …System Views systemd RemoveIPCManual ChaptersPG1818.4.2. systemd RemoveIPC If systemd is in use, some care must be taken that IPC resources (including shared memory) are not prematurely removed by the operating system. This is especially o…systemd RemoveIPC Table Access Method Interface DefinitionManual ChaptersPG18Chapter 62. Table Access Method Interface Definition This chapter explains the interface between the core PostgreSQL system and table access methods, which manage the storage for tables. The…Table Access Method Interface Definition Table Access MethodsManual ChaptersPG18Table Access Methods You may specify the Table Access Method for the pgbench tables. The environment variable PGOPTIONS specifies database configuration options that are passed to PostgreSQL…Table Access Methods Table and Column AliasesManual ChaptersPG187.2.1.2. Table and Column Aliases A temporary name can be given to tables and complex table references to be used for references to the derived table in the rest of the query. This is called…Table and Column Aliases Table BasicsManual ChaptersPG185.1. Table Basics A table in a relational database is much like a table on paper: It consists of rows and columns. The number and order of the columns is fixed, and each column has a name. T…Table Basics TABLE CommandManual ChaptersPG18TABLE Command The command TABLE name is equivalent to SELECT * FROM name It can be used as a top-level command or as a space-saving syntax variant in parts of complex queries. Only the WITH,…TABLE Command Table ExpressionsManual ChaptersPG187.2. Table Expressions A table expression computes a table. The table expression contains a FROM clause that is optionally followed by WHERE, GROUP BY, and HAVING clauses. Trivial table expr…Table Expressions Table FunctionsManual ChaptersPG187.2.1.4. Table Functions Table functions are functions that produce a set of rows, made up of either base data types (scalar types) or composite data types (table rows). They are used like a…Table Functions Table PartitioningManual ChaptersPG185.12. Table Partitioning PostgreSQL supports basic table partitioning. This section describes why and how to implement partitioning as part of your database design.Table Partitioning Table Row LayoutManual ChaptersPG1866.6.1. Table Row Layout All table rows are structured in the same way. There is a fixed-size header (occupying 23 bytes on most machines), followed by an optional null bitmap, an optional o…Table Row Layout Table-Level LocksManual ChaptersPG1813.3.1. Table-Level Locks The list below shows the available lock modes and the contexts in which they are used automatically by PostgreSQL. You can also acquire any of these locks explicitl…Table-Level Locks table_constraintsManual ChaptersPG1835.52. table_constraints The view table_constraints contains all constraints belonging to tables that the current user owns or has some privilege other than SELECT on. Table 35.50. table_con…table_constraints table_privilegesManual ChaptersPG1835.53. table_privileges The view table_privileges identifies all privileges granted on tables or views to a currently enabled role or by a currently enabled role. There is one row for each c…table_privileges table_rewriteManual ChaptersPG1838.1.5. table_rewrite The table_rewrite event occurs just before a table is rewritten by some actions of the commands ALTER TABLE and ALTER TYPE. While other control statements are available…table_rewrite tablefunc — functions that return tables (crosstab and others)Manual ChaptersPG18F.43. tablefunc — functions that return tables (crosstab and others) The tablefunc module includes various functions that return tables (that is, multiple rows). These functions are useful b…tablefunc — functions that return tables (crosstab and others) tablesManual ChaptersPG1835.54. tables The view tables contains all tables and views defined in the current database. Only those tables and views are shown that the current user has access to (by way of being the ow…tables Tables and IndexesManual ChaptersPG1812.2. Tables and Indexes The examples in the previous section illustrated full text matching using simple constant strings. This section shows how to search table data, optionally using inde…Tables and Indexes TABLESAMPLE Clause RestrictionsManual ChaptersPG18TABLESAMPLE Clause Restrictions The TABLESAMPLE clause is currently accepted only on regular tables and materialized views. According to the SQL standard it should be possible to apply it to…TABLESAMPLE Clause Restrictions