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The pg_buffercache_numa ViewManual ChaptersPG18F.25.2. The pg_buffercache_numa View The definitions of the columns exposed by the view are shown in Table F.15. Table F.15. pg_buffercache_numa Columns Column Type Description bufferid inte…The pg_buffercache_numa View The pg_buffercache_summary() FunctionManual ChaptersPG18F.25.3. The pg_buffercache_summary() Function The definitions of the columns exposed by the function are shown in Table F.16. Table F.16. pg_buffercache_summary() Output Columns Column Type …The pg_buffercache_summary() Function The pg_buffercache_usage_counts() FunctionManual ChaptersPG18F.25.4. The pg_buffercache_usage_counts() Function The definitions of the columns exposed by the function are shown in Table F.17. Table F.17. pg_buffercache_usage_counts() Output Columns Co…The pg_buffercache_usage_counts() Function The pg_hba.conf FileManual ChaptersPG1820.1. The pg_hba.conf File Client authentication is controlled by a configuration file, which traditionally is named pg_hba.conf and is stored in the database cluster's data directory. (HBA …The pg_hba.conf File The pg_stat_statements ViewManual ChaptersPG18F.32.1. The pg_stat_statements View The statistics gathered by the module are made available via a view named pg_stat_statements. This view contains one row for each distinct combination of …The pg_stat_statements View The pg_stat_statements_info ViewManual ChaptersPG18F.32.2. The pg_stat_statements_info View The statistics of the pg_stat_statements module itself are tracked and made available via a view named pg_stat_statements_info. This view contains on…The pg_stat_statements_info View The PostgreSQL Rule SystemManual ChaptersPG1851.4. The PostgreSQL Rule System PostgreSQL supports a powerful rule system for the specification of views and ambiguous view updates. Originally the PostgreSQL rule system consisted of two …The PostgreSQL Rule System The PostgreSQL Type SystemManual ChaptersPG1836.2. The PostgreSQL Type System PostgreSQL data types can be divided into base types, container types, domains, and pseudo-types.The PostgreSQL Type System The PostgreSQL User AccountManual ChaptersPG1818.1. The PostgreSQL User Account As with any server daemon that is accessible to the outside world, it is advisable to run PostgreSQL under a separate user account. This user account should…The PostgreSQL User Account The Power of Views in PostgreSQLManual ChaptersPG1839.2.3. The Power of Views in PostgreSQL The above demonstrates how the rule system incorporates view definitions into the original query tree. In the second example, a simple SELECT from on…The Power of Views in PostgreSQL The Public SchemaManual ChaptersPG185.10.2. The Public Schema In the previous sections we created tables without specifying any schema names. By default such tables (and other objects) are automatically put into a schema named…The Public Schema The Query TreeManual ChaptersPG1839.1. The Query Tree To understand how the rule system works it is necessary to know when it is invoked and what its input and results are. The rule system is located between the parser and …The Query Tree The Rule SystemManual ChaptersPG18Chapter 39. The Rule System This chapter discusses the rule system in PostgreSQL. Production rule systems are conceptually simple, but there are many subtle points involved in actually using…The Rule System The SchemaManual ChaptersPG1835.1. The Schema The information schema itself is a schema named information_schema. This schema automatically exists in all databases. The owner of this schema is the initial database user …The Schema The Schema Search PathManual ChaptersPG185.10.3. The Schema Search Path Qualified names are tedious to write, and it's often best not to wire a particular schema name into applications anyway. Therefore tables are often referred to…The Schema Search Path The Source Code RepositoryManual ChaptersPG18Appendix I. The Source Code Repository The PostgreSQL source code is stored and managed using the Git version control system. A public mirror of the master repository is available; it is upd…The Source Code Repository The SQL LanguageManual ChaptersPG18Part II. The SQL Language This part describes the use of the SQL language in PostgreSQL. We start with describing the general syntax of SQL, then how to create tables, how to populate the da…The SQL Language The SQL LanguageManual ChaptersPG18Chapter 2. The SQL LanguageThe SQL Language The SQL/JSON Path LanguageManual ChaptersPG189.16.2. The SQL/JSON Path Language SQL/JSON path expressions specify item(s) to be retrieved from a JSON value, similarly to XPath expressions used for access to XML content. In PostgreSQL, …The SQL/JSON Path Language The System Catalog SchemaManual ChaptersPG185.10.5. The System Catalog Schema In addition to public and user-created schemas, each database contains a pg_catalog schema, which contains the system tables and all the built-in data types…The System Catalog Schema The timestamp TypeManual ChaptersPG1834.6.4. The timestamp Type The timestamp type in C enables your programs to deal with data of the SQL type timestamp. See Section 8.5 for the equivalent type in the PostgreSQL server. The fo…The timestamp Type The WHERE ClauseManual ChaptersPG187.2.2. The WHERE Clause The syntax of the WHERE clause is WHERE search_condition where search_condition is any value expression (see Section 4.2) that returns a value of type boolean. After …The WHERE Clause The “random” TestManual ChaptersPG1831.2.7. The “random” Test The random test script is intended to produce random results. In very rare cases, this causes that regression test to fail. Typing: diff results/random.out expected…The “random” Test Thesaurus ConfigurationManual ChaptersPG1812.6.4.1. Thesaurus Configuration To define a new thesaurus dictionary, use the thesaurus template. For example: CREATE TEXT SEARCH DICTIONARY thesaurus_simple ( TEMPLATE = thesaurus, DictFi…Thesaurus Configuration Thesaurus DictionaryManual ChaptersPG1812.6.4. Thesaurus Dictionary A thesaurus dictionary (sometimes abbreviated as TZ) is a collection of words that includes information about the relationships of words and phrases, i.e., broad…Thesaurus Dictionary Thesaurus ExampleManual ChaptersPG1812.6.4.2. Thesaurus Example Consider a simple astronomical thesaurus thesaurus_astro, which contains some astronomical word combinations: supernovae stars : sn crab nebulae : crab Below we c…Thesaurus Example Time StampsManual ChaptersPG188.5.1.3. Time Stamps Valid input for the time stamp types consists of the concatenation of a date and a time, followed by an optional time zone, followed by an optional AD or BC. (Alternativ…Time Stamps Time ZonesManual ChaptersPG188.5.3. Time Zones Time zones, and time-zone conventions, are influenced by political decisions, not just earth geometry. Time zones around the world became somewhat standardized during the 1…Time Zones TimelinesManual ChaptersPG1825.3.6. Timelines The ability to restore the database to a previous point in time creates some complexities that are akin to science-fiction stories about time travel and parallel universes.…Timelines TimesManual ChaptersPG188.5.1.2. Times The time-of-day types are time [ (p) ] without time zone and time [ (p) ] with time zone. time alone is equivalent to time without time zone. Valid input for these types consi…Times timestamp, dateManual ChaptersPG1834.4.4.2.1. timestamp, date Here is a pattern for handling timestamp variables in the ECPG host application. First, the program has to include the header file for the timestamp type: include…timestamp, date Tips and ExamplesManual ChaptersPG1825.3.7. Tips and Examples Some tips for configuring continuous archiving are given here.Tips and Examples Tips for Developing in PL/pgSQLManual ChaptersPG1841.12. Tips for Developing in PL/pgSQL One good way to develop in PL/pgSQL is to use the text editor of your choice to create your functions, and in another window, use psql to load and test…Tips for Developing in PL/pgSQL TOASTManual ChaptersPG1866.2. TOAST This section provides an overview of TOAST (The Oversized-Attribute Storage Technique). PostgreSQL uses a fixed page size (commonly 8 kB), and does not allow tuples to span multi…TOAST TOAST ConsiderationsManual ChaptersPG1836.13.1. TOAST Considerations If the values of your data type vary in size (in internal form), it's usually desirable to make the data type TOAST-able (see Section 66.2). You should do this …TOAST Considerations Tool SetsManual ChaptersPG18J.2. Tool Sets The following tools are used to process the documentation. Some might be optional, as noted. DocBook DTD # This is the definition of DocBook itself. We currently use version 4…Tool Sets Transaction Begin CallbackManual ChaptersPG1847.6.4.3. Transaction Begin Callback The required begin_cb callback is called whenever a start of a committed transaction has been decoded. Aborted transactions and their contents never get …Transaction Begin Callback Transaction Begin Prepare CallbackManual ChaptersPG1847.6.4.10. Transaction Begin Prepare Callback The required begin_prepare_cb callback is called whenever the start of a prepared transaction has been decoded. The gid field, which is part of …Transaction Begin Prepare Callback Transaction Commit Prepared CallbackManual ChaptersPG1847.6.4.12. Transaction Commit Prepared Callback The required commit_prepared_cb callback is called whenever a transaction COMMIT PREPARED has been decoded. The gid field, which is part of th…Transaction Commit Prepared Callback Transaction End CallbackManual ChaptersPG1847.6.4.4. Transaction End Callback The required commit_cb callback is called whenever a transaction commit has been decoded. The change_cb callbacks for all modified rows will have been call…Transaction End Callback