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A Brief History of PostgreSQLManual ChaptersPG182. A Brief History of PostgreSQL The object-relational database management system now known as PostgreSQL is derived from the POSTGRES package written at the University of California at Berk…A Brief History of PostgreSQL A Complete Event Trigger ExampleManual ChaptersPG1838.3. A Complete Event Trigger Example Here is a very simple example of an event trigger function written in C. (Examples of triggers written in procedural languages can be found in the docu…A Complete Event Trigger Example A Complete Trigger ExampleManual ChaptersPG1837.4. A Complete Trigger Example Here is a very simple example of a trigger function written in C. (Examples of triggers written in procedural languages can be found in the documentation of …A Complete Trigger Example A Database Login Event Trigger ExampleManual ChaptersPG1838.5. A Database Login Event Trigger Example The event trigger on the login event can be useful for logging user logins, for verifying the connection and assigning roles according to current…A Database Login Event Trigger Example A First Rule Step by StepManual ChaptersPG1839.4.1.1. A First Rule Step by Step Say we want to trace changes to the sl_avail column in the shoelace_data relation. So we set up a log table and a rule that conditionally writes a log ent…A First Rule Step by Step A Sample Application Using SQLDAManual ChaptersPG1834.7.2.4. A Sample Application Using SQLDA Here is an example program, which describes how to fetch access statistics of the databases, specified by the input parameters, from the system cat…A Sample Application Using SQLDA A Table Rewrite Event Trigger ExampleManual ChaptersPG1838.4. A Table Rewrite Event Trigger Example Thanks to the table_rewrite event, it is possible to implement a table rewriting policy only allowing the rewrite in maintenance windows. Here's a…A Table Rewrite Event Trigger Example ABI CompatibilityManual ChaptersPG1836.10.6.3. ABI Compatibility The ABI, or application binary interface, is the interface used at run time.ABI Compatibility ABORTManual ChaptersPG18ABORT ABORT — abort the current transaction Synopsis ABORT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]ABORT Access Privilege Inquiry FunctionsManual ChaptersPG189.27.2. Access Privilege Inquiry Functions Table 9.72 lists functions that allow querying object access privileges programmatically. (See Section 5.8 for more information about privileges.) …Access Privilege Inquiry Functions Accessing a DatabaseManual ChaptersPG181.4. Accessing a Database Once you have created a database, you can access it by: Running the PostgreSQL interactive terminal program, called psql, which allows you to interactively enter, e…Accessing a Database Accessing ArraysManual ChaptersPG188.15.3. Accessing Arrays Now, we can run some queries on the table. First, we show how to access a single element of an array. This query retrieves the names of the employees whose pay chang…Accessing Arrays Accessing Composite TypesManual ChaptersPG188.16.3. Accessing Composite Types To access a field of a composite column, one writes a dot and the field name, much like selecting a field from a table name. In fact, it's so much like sele…Accessing Composite Types Accessing Special Data TypesManual ChaptersPG1834.4.4.2. Accessing Special Data Types ECPG contains some special types that help you to interact easily with some special data types from the PostgreSQL server. In particular, it has implem…Accessing Special Data Types Accessing XML ValuesManual ChaptersPG188.13.3. Accessing XML Values The xml data type is unusual in that it does not provide any comparison operators. This is because there is no well-defined and universally useful comparison alg…Accessing XML Values AcknowledgmentsManual ChaptersPG18E.6.4. Acknowledgments The following individuals (in alphabetical order) have contributed to this release as patch authors, committers, reviewers, testers, or reporters of issues. Abhishek C…Acknowledgments AcronymsManual ChaptersPG18Appendix L. Acronyms This is a list of acronyms commonly used in the PostgreSQL documentation and in discussions about PostgreSQL. AIO Asynchronous I/O ACL Access Control List AM Access Meth…Acronyms Adding a ColumnManual ChaptersPG185.7.1. Adding a Column To add a column, use a command like: ALTER TABLE products ADD COLUMN description text; The new column is initially filled with whatever default value is given (null if…Adding a Column Adding a ConstraintManual ChaptersPG185.7.3. Adding a Constraint To add a constraint, the table constraint syntax is used. For example: ALTER TABLE products ADD CHECK (name <> ''); ALTER TABLE products ADD CONSTRAINT some_name U…Adding a Constraint Additional Compile-Time and Run-Time ChecksManual ChaptersPG1841.12.2. Additional Compile-Time and Run-Time Checks To aid the user in finding instances of simple but common problems before they cause harm, PL/pgSQL provides additional checks. When enab…Additional Compile-Time and Run-Time Checks Additional ConstantsManual ChaptersPG1834.15.5. Additional Constants Note that all constants here describe errors and all of them are defined to represent negative values. In the descriptions of the different constants you can al…Additional Constants Additional FeaturesManual ChaptersPG1812.4. Additional Features This section describes additional functions and operators that are useful in connection with text search.Additional Features Additional FunctionsManual ChaptersPG1834.15.4. Additional Functions decadd Add two decimal type values. int decadd(decimal *arg1, decimal *arg2, decimal *sum); The function receives a pointer to the first operand of type decimal…Additional Functions Additional ModulesManual ChaptersPG18E.6.3.9. Additional Modules Add extension pg_logicalinspect to inspect logical snapshots (Bertrand Drouvot) § Add extension pg_overexplain which adds debug details to EXPLAIN output (Robert …Additional Modules Additional Supplied Modules and ExtensionsManual ChaptersPG18Appendix F. Additional Supplied Modules and Extensions This appendix and the next one contain information on the optional components found in the contrib directory of the PostgreSQL distribu…Additional Supplied Modules and Extensions Additional Supplied ProgramsManual ChaptersPG18Appendix G. Additional Supplied Programs This appendix and the previous one contain information regarding the modules that can be found in the contrib directory of the PostgreSQL distributio…Additional Supplied Programs Additional Test SuitesManual ChaptersPG1831.1.3. Additional Test Suites The make check and make installcheck commands run only the “core” regression tests, which test built-in functionality of the PostgreSQL server. The source dist…Additional Test Suites Additional TypesManual ChaptersPG1834.15.1. Additional Types The Informix-special "string" pseudo-type for storing right-trimmed character string data is now supported in Informix-mode without using typedef. In fact, in Infor…Additional Types Additional/Missing Embedded SQL StatementsManual ChaptersPG1834.15.2. Additional/Missing Embedded SQL Statements CLOSE DATABASE # This statement closes the current connection. In fact, this is a synonym for ECPG's DISCONNECT CURRENT: $CLOSE DATABASE; …Additional/Missing Embedded SQL Statements administrable_role_​authorizationsManual ChaptersPG1835.4. administrable_role_​authorizations The view administrable_role_authorizations identifies all roles that the current user has the admin option for. Table 35.2. administrable_role_author…administrable_role_​authorizations Administration ToolsManual ChaptersPG18H.2. Administration Tools There are several administration tools available for PostgreSQL. The most popular is pgAdmin, and there are several commercially available ones as well.Administration Tools Administrator's OverviewManual ChaptersPG1826.4.3. Administrator's Overview If hot_standby is on in postgresql.conf (the default value) and there is a standby.signal file present, the server will run in hot standby mode. However, it …Administrator's Overview Advanced FeaturesManual ChaptersPG18Advanced FeaturesAdvanced Features Advanced FeaturesManual ChaptersPG18Chapter 3. Advanced FeaturesAdvanced Features Advantages of Using PL/pgSQLManual ChaptersPG1841.1.1. Advantages of Using PL/pgSQL SQL is the language PostgreSQL and most other relational databases use as query language. It's portable and easy to learn. But every SQL statement must b…Advantages of Using PL/pgSQL Advisory Lock FunctionsManual ChaptersPG189.28.10. Advisory Lock Functions The functions shown in Table 9.109 manage advisory locks. For details about proper use of these functions, see Section 13.3.5. All these functions are intend…Advisory Lock Functions Advisory LocksManual ChaptersPG1813.3.5. Advisory Locks PostgreSQL provides a means for creating locks that have application-defined meanings. These are called advisory locks, because the system does not enforce their use —…Advisory Locks Aggregate ExpressionsManual ChaptersPG184.2.7. Aggregate Expressions An aggregate expression represents the application of an aggregate function across the rows selected by a query. An aggregate function reduces multiple inputs to…Aggregate Expressions Aggregate FunctionsManual ChaptersPG189.21. Aggregate Functions Aggregate functions compute a single result from a set of input values. The built-in general-purpose aggregate functions are listed in Table 9.62 while statistical …Aggregate Functions Aggregate FunctionsManual ChaptersPG182.7. Aggregate Functions Like most other relational database products, PostgreSQL supports aggregate functions. An aggregate function computes a single result from multiple input rows. For e…Aggregate Functions