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CompatibilityManual ChaptersPG18Compatibility VALUES conforms to the SQL standard. LIMIT and OFFSET are PostgreSQL extensions; see also under SELECT.Compatibility Compiling and Linking Dynamically-Loaded FunctionsManual ChaptersPG1836.10.5. Compiling and Linking Dynamically-Loaded Functions Before you are able to use your PostgreSQL extension functions written in C, they must be compiled and linked in a special way to …Compiling and Linking Dynamically-Loaded Functions Compiling for Dynamic TracingManual ChaptersPG1827.5.1. Compiling for Dynamic Tracing By default, probes are not available, so you will need to explicitly tell the configure script to make the probes available in PostgreSQL. To include DT…Compiling for Dynamic Tracing Compiling for Optimal PerformanceManual ChaptersPG1817.7.4.3. Compiling for Optimal Performance On the SPARC architecture, Sun Studio is strongly recommended for compilation. Try using the -xO5 optimization flag to generate significantly fast…Compiling for Optimal Performance complexExtensionsExtensionsComplex-number data type for PostgreSQL. data-type math complex_contrib Data typesData types · Extensions compositeExtensionsExtensionsaggregates and functions for PostgreSQL Server aggregates c custom-aggregates extension functions postgresql postgresql-extension composite Functions and aggregatesFunctions and aggregates · Extensions Composite Type ComparisonManual ChaptersPG189.25.6. Composite Type Comparison record operator record The SQL specification requires row-wise comparison to return NULL if the result depends on comparing two NULL values or a NULL and a …Composite Type Comparison Composite Type Input and Output SyntaxManual ChaptersPG188.16.6. Composite Type Input and Output Syntax The external text representation of a composite value consists of items that are interpreted according to the I/O conversion rules for the indi…Composite Type Input and Output Syntax Composite TypesManual ChaptersPG1834.4.5.2. Composite Types Composite types are not directly supported in ECPG, but an easy workaround is possible. The available workarounds are similar to the ones described for arrays above…Composite Types Composite TypesManual ChaptersPG1844.2.4. Composite Types Composite-type arguments are passed to the function as Python mappings. The element names of the mapping are the attribute names of the composite type. If an attribut…Composite Types Composite TypesManual ChaptersPG188.16. Composite Types A composite type represents the structure of a row or record; it is essentially just a list of field names and their data types. PostgreSQL allows composite types to be…Composite Types Composite TypesManual ChaptersPG18Composite Types The first form of CREATE TYPE creates a composite type. The composite type is specified by a list of attribute names and data types. An attribute's collation can be specified…Composite Types Composite-Type ArgumentsManual ChaptersPG1836.10.7. Composite-Type Arguments Composite types do not have a fixed layout like C structures. Instances of a composite type can contain null fields. In addition, composite types that are p…Composite-Type Arguments compressExtensionsExtensionsC/C++ functions to compress text into Base64-encoded ZIP archives and extract text from them. base64 compression zip pg_compress UtilitiesUtilities · Extensions compress-algoManual ChaptersPG18F.26.3.8.2. compress-algo Which compression algorithm to use. Only available if PostgreSQL was built with zlib. Values: 0 - no compression 1 - ZIP compression 2 - ZLIB compression (= ZIP plu…compress-algo compress-levelManual ChaptersPG18F.26.3.8.3. compress-level How much to compress. Higher levels compress smaller but are slower. 0 disables compression. Values: 0, 1-9 Default: 6 Applies to: pgp_sym_encrypt, pgp_pub_encryptcompress-level Compressed Archive LogsManual ChaptersPG1825.3.7.2. Compressed Archive Logs If archive storage size is a concern, you can use gzip to compress the archive files: archive_command = 'gzip < %p > /mnt/server/archivedir/%f.gz' You will …Compressed Archive Logs compute_query_idConfigurationReferencecompute_query_id Statistics 14 Enables in-core computation of a query identifier. Query identifiers can be displayed in the pg_stat_activity view, using EXPLAIN, or emitted in the log if con…Configuration · Statistics concatFunctionsReferenceconcat String Functions And Operators 10 Concatenate the text representations of all the arguments. NULL arguments are ignored. concat ( str "any" [, str "any" [, ...] ] ) → text Concatenate…Functions · String Functions And Operators concat_wsFunctionsReferenceconcat_ws String Functions And Operators 10 Concatenate all but the first argument with separators. The first argument is used as the separator string. NULL arguments are ignored. concat_ws …Functions · String Functions And Operators ConceptsManual ChaptersPG1823.2.1. Concepts Conceptually, every expression of a collatable data type has a collation. (The built-in collatable data types are text, varchar, and char. User-defined base types can also b…Concepts ConceptsManual ChaptersPG1856.1.2. Concepts The pairs of original (English) messages and their (possibly) translated equivalents are kept in message catalogs, one for each program (although related programs can share …Concepts ConceptsManual ChaptersPG182.2. Concepts PostgreSQL is a relational database management system (RDBMS). That means it is a system for managing data stored in relations. Relation is essentially a mathematical term for …Concepts ConclusionManual ChaptersPG183.7. Conclusion PostgreSQL has many features not touched upon in this tutorial introduction, which has been oriented toward newer users of SQL. These features are discussed in more detail in…Conclusion Concurrency ControlManual ChaptersPG18Chapter 13. Concurrency Control This chapter describes the behavior of the PostgreSQL database system when two or more sessions try to access the same data at the same time. The goals in tha…Concurrency Control conda_pgsql_rust_extExtensionsExtensionsConda version data type and helpers for PostgreSQL, implemented with pgrx and rattler_conda_types. conda data-type pgrx data_experiments Data typesData types · Extensions condaversionExtensionsExtensionsConda package version number data type implemented as a C++ PostgreSQL extension. data-type data_experiments Data typesData types · Extensions Conditional ExpressionsManual ChaptersPG189.18. Conditional Expressions This section describes the SQL-compliant conditional expressions available in PostgreSQL. Tip If your needs go beyond the capabilities of these conditional expr…Conditional Expressions ConditionalsManual ChaptersPG1841.6.4. Conditionals IF and CASE statements let you execute alternative commands based on certain conditions. PL/pgSQL has three forms of IF: IF ... THEN ... END IF IF ... THEN ... ELSE ... …Conditionals config_fileConfigurationReferenceconfig_file File Locations 10 Specifies the main server configuration file (customarily called postgresql.conf). This parameter can only be set on the postgres command line. 11 12 13 14 15 1…Configuration · File Locations config_logExtensionsExtensionscustom background worker process to log changes to postgresql.conf to a table background-worker configuration monitoring config_log MonitoringMonitoring · Extensions ConfigurationManual ChaptersPG18F.12.1. Configuration The dictionary accepts three options: The maxlen parameter specifies the maximum number of digits allowed in an integer word. The default value is 6. The rejectlong par…Configuration ConfigurationManual ChaptersPG18F.13.1. Configuration A dict_xsyn dictionary accepts the following options: matchorig controls whether the original word is accepted by the dictionary. Default is true. matchsynonyms control…Configuration ConfigurationManual ChaptersPG1830.3. Configuration The configuration variable jit determines whether JIT compilation is enabled or disabled. If it is enabled, the configuration variables jit_above_cost, jit_inline_above_c…Configuration ConfigurationManual ChaptersPG18F.26.8.1. Configuration pgcrypto configures itself according to the findings of the main PostgreSQL configure script. The options that affect it are --with-zlib and --with-ssl=openssl. When …Configuration ConfigurationManual ChaptersPG1843.8.1. Configuration This section lists configuration parameters that affect PL/Perl. plperl.on_init (string) # Specifies Perl code to be executed when a Perl interpreter is first initializ…Configuration ConfigurationManual ChaptersPG18F.48.1. Configuration An unaccent dictionary accepts the following options: RULES is the base name of the file containing the list of translation rules. This file must be stored in $SHAREDIR…Configuration Configuration ExampleManual ChaptersPG1812.7. Configuration Example A text search configuration specifies all options necessary to transform a document into a tsvector: the parser to use to break text into tokens, and the dictiona…Configuration Example Configuration ExampleManual ChaptersPG1826.2.6.2. Configuration Example You can create a replication slot like this: postgres=# SELECT * FROM pg_create_physical_replication_slot('node_a_slot'); slot_name | lsn -------------+----- …Configuration Example Configuration ParametersManual ChaptersPG18F.2.1. Configuration Parameters auth_delay.milliseconds (integer) The number of milliseconds to wait before reporting an authentication failure. The default is 0. These parameters must be se…Configuration Parameters