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Utility CommandsManual ChaptersPG18E.6.3.2. Utility Commands Allow generated columns to be virtual, and make them the default (Peter Eisentraut, Jian He, Richard Guo, Dean Rasheed) § § § Virtual generated columns generate the…Utility Commands Utility FunctionsManual ChaptersPG1844.9. Utility Functions The plpy module also provides the functions plpy.debug(msg, **kwargs) plpy.log(msg, **kwargs) plpy.info(msg, **kwargs) plpy.notice(msg, **kwargs) plpy.warning(msg, **…Utility Functions Utility Functions in PL/PerlManual ChaptersPG1843.3.2. Utility Functions in PL/Perl elog(level, msg) Emit a log or error message. Possible levels are DEBUG, LOG, INFO, NOTICE, WARNING, and ERROR. ERROR raises an error condition; if this …Utility Functions in PL/Perl UUID FunctionsManual ChaptersPG189.14. UUID Functions Table 9.45 shows the PostgreSQL functions that can be used to generate UUIDs. Table 9.45. UUID Generation Functions Function Description Example(s) gen_random_uuid ( ) →…UUID Functions UUID TypeManual ChaptersPG188.12. UUID Type The data type uuid stores Universally Unique Identifiers (UUID) as defined by RFC 9562, ISO/IEC 9834-8:2005, and related standards. (Some systems refer to this data type as a…UUID Type uuid-ossp FunctionsManual ChaptersPG18F.49.1. uuid-ossp Functions Table F.35 shows the functions available to generate UUIDs. The relevant standards ITU-T Rec. X.667, ISO/IEC 9834-8:2005, and RFC 4122 specify four algorithms for…uuid-ossp Functions uuid-ossp — a UUID generatorManual ChaptersPG18F.49. uuid-ossp — a UUID generator The uuid-ossp module provides functions to generate universally unique identifiers (UUIDs) using one of several standard algorithms. There are also functio…uuid-ossp — a UUID generator VACUUMManual ChaptersPG18VACUUM VACUUM — garbage-collect and optionally analyze a database Synopsis VACUUM [ ( option [, ...] ) ] [ table_and_columns [, ...] ] where option can be one of: FULL [ boolean ] FREEZE [ b…VACUUM VACUUM Progress ReportingManual ChaptersPG1827.4.5. VACUUM Progress Reporting Whenever VACUUM is running, the pg_stat_progress_vacuum view will contain one row for each backend (including autovacuum worker processes) that is currently…VACUUM Progress Reporting vacuumdbManual ChaptersPG18vacuumdb vacuumdb — garbage-collect and analyze a PostgreSQL database Synopsis vacuumdb [connection-option...] [option...] [ -t | --table table [( column [,...] )] ] ... [ dbname | -a | --al…vacuumdb VacuumingManual ChaptersPG1819.10. Vacuuming These parameters control vacuuming behavior. For more information on the purpose and responsibilities of vacuum, see Section 24.1.Vacuuming Vacuuming BasicsManual ChaptersPG1824.1.1. Vacuuming Basics PostgreSQL's VACUUM command has to process each table on a regular basis for several reasons: To recover or reuse disk space occupied by updated or deleted rows. To …Vacuuming Basics vacuumloManual ChaptersPG18vacuumlo vacuumlo — remove orphaned large objects from a PostgreSQL database Synopsis vacuumlo [option...] dbname...vacuumlo Validate CallbackManual ChaptersPG1850.3.2. Validate Callback The validate_cb callback is executed during the OAuth exchange when a user attempts to authenticate using OAuth. Any state set in previous calls will be available i…Validate Callback Validator ResponsibilitiesManual ChaptersPG1850.1.1. Validator Responsibilities Although different modules may take very different approaches to token validation, implementations generally need to perform three separate actions: Valida…Validator Responsibilities Value ExpressionsManual ChaptersPG184.2. Value Expressions Value expressions are used in a variety of contexts, such as in the target list of the SELECT command, as new column values in INSERT or UPDATE, or in search condition…Value Expressions Value StorageManual ChaptersPG1810.4. Value Storage Values to be inserted into a table are converted to the destination column's data type according to the following steps. Value Storage Type Conversion Check for an exact …Value Storage VALUESManual ChaptersPG18VALUES VALUES — compute a set of rows Synopsis VALUES ( expression [, ...] ) [, ...] [ ORDER BY sort_expression [ ASC | DESC | USING operator ] [, ...] ] [ LIMIT { count | ALL } ] [ OFFSET s…VALUES VALUES ListsManual ChaptersPG187.7. VALUES Lists VALUES provides a way to generate a “constant table” that can be used in a query without having to actually create and populate a table on-disk. The syntax is VALUES ( expr…VALUES Lists VARManual ChaptersPG18VAR VAR — define a variable Synopsis VAR varname IS ctypeVAR Variable SubstitutionManual ChaptersPG1841.11.1. Variable Substitution SQL statements and expressions within a PL/pgSQL function can refer to variables and parameters of the function. Behind the scenes, PL/pgSQL substitutes query …Variable Substitution VariablesManual ChaptersPG18Variables psql provides variable substitution features similar to common Unix command shells. Variables are simply name/value pairs, where the value can be any string of any length. The name…Variables Variant Comparison FilesManual ChaptersPG1831.3. Variant Comparison Files Since some of the tests inherently produce environment-dependent results, we have provided ways to specify alternate “expected” result files. Each regression t…Variant Comparison Files Version 1 Calling ConventionsManual ChaptersPG1836.10.3. Version 1 Calling Conventions The version-1 calling convention relies on macros to suppress most of the complexity of passing arguments and results. The C declaration of a version-1…Version 1 Calling Conventions Version and Platform CompatibilityManual ChaptersPG1819.13. Version and Platform CompatibilityVersion and Platform Compatibility Version Information FunctionsManual ChaptersPG189.27.11. Version Information Functions The functions shown in Table 9.93 print version information. Table 9.93. Version Information Functions Function Description version () → text Returns a…Version Information Functions View Rules in Non-SELECT StatementsManual ChaptersPG1839.2.2. View Rules in Non-SELECT Statements Two details of the query tree aren't touched in the description of view rules above. These are the command type and the result relation. In fact, …View Rules in Non-SELECT Statements view_column_usageManual ChaptersPG1835.63. view_column_usage The view view_column_usage identifies all columns that are used in the query expression of a view (the SELECT statement that defines the view). A column is only incl…view_column_usage view_routine_usageManual ChaptersPG1835.64. view_routine_usage The view view_routine_usage identifies all routines (functions and procedures) that are used in the query expression of a view (the SELECT statement that defines th…view_routine_usage view_table_usageManual ChaptersPG1835.65. view_table_usage The view view_table_usage identifies all tables that are used in the query expression of a view (the SELECT statement that defines the view). A table is only included…view_table_usage Viewing LocksManual ChaptersPG1827.3. Viewing Locks Another useful tool for monitoring database activity is the pg_locks system table. It allows the database administrator to view information about the outstanding locks in…Viewing Locks Viewing StatisticsManual ChaptersPG1827.2.2. Viewing Statistics Several predefined views, listed in Table 27.1, are available to show the current state of the system. There are also several other views, listed in Table 27.2, av…Viewing Statistics viewsManual ChaptersPG1835.66. views The view views contains all views defined in the current database. Only those views are shown that the current user has access to (by way of being the owner or having some privi…views ViewsManual ChaptersPG183.2. Views Refer back to the queries in Section 2.6. Suppose the combined listing of weather records and city location is of particular interest to your application, but you do not want to t…Views Views and the Rule SystemManual ChaptersPG1839.2. Views and the Rule System Views in PostgreSQL are implemented using the rule system. A view is basically an empty table (having no actual storage) with an ON SELECT DO INSTEAD rule. Co…Views and the Rule System Visibility MapManual ChaptersPG1866.4. Visibility Map Each heap relation has a Visibility Map (VM) to keep track of which pages contain only tuples that are known to be visible to all active transactions; it also keeps trac…Visibility Map Visibility of Data ChangesManual ChaptersPG1845.5. Visibility of Data Changes The following rules govern the visibility of data changes in functions that use SPI (or any other C function): During the execution of an SQL command, any da…Visibility of Data Changes Visibility of Data ChangesManual ChaptersPG1837.2. Visibility of Data Changes If you execute SQL commands in your trigger function, and these commands access the table that the trigger is for, then you need to be aware of the data visi…Visibility of Data Changes Visual StudioManual ChaptersPG1817.7.5. Visual Studio It is recommended that most users download the binary distribution for Windows, available as a graphical installer package from the PostgreSQL website at https://www.po…Visual Studio Wait EventsManual ChaptersPG18F.38.8. Wait Events postgres_fdw can report the following wait events under the wait event type Extension: PostgresFdwCleanupResult Waiting for transaction abort on remote server. PostgresFd…Wait Events