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SQL/JSON Path Operators and MethodsManual ChaptersPG189.16.2.3. SQL/JSON Path Operators and Methods Table 9.52 shows the operators and methods available in jsonpath. Note that while the unary operators and methods can be applied to multiple val…SQL/JSON Path Operators and Methods SQL/JSON Query FunctionsManual ChaptersPG189.16.3. SQL/JSON Query Functions SQL/JSON functions JSON_EXISTS(), JSON_QUERY(), and JSON_VALUE() described in Table 9.54 can be used to query JSON documents. Each of these functions apply a…SQL/JSON Query Functions SQL/JSON Regular ExpressionsManual ChaptersPG189.16.2.4. SQL/JSON Regular Expressions SQL/JSON path expressions allow matching text to a regular expression with the like_regex filter. For example, the following SQL/JSON path query would …SQL/JSON Regular Expressions sql_dropManual ChaptersPG1838.1.4. sql_drop The sql_drop event occurs just before the ddl_command_end event trigger for any operation that drops database objects. Note that besides the obvious DROP commands, some ALTE…sql_drop sql_featuresManual ChaptersPG1835.48. sql_features The table sql_features contains information about which formal features defined in the SQL standard are supported by PostgreSQL. This is the same information that is pres…sql_features sql_implementation_infoManual ChaptersPG1835.49. sql_implementation_info The table sql_implementation_info contains information about various aspects that are left implementation-defined by the SQL standard. This information is prim…sql_implementation_info sql_partsManual ChaptersPG1835.50. sql_parts The table sql_parts contains information about which of the several parts of the SQL standard are supported by PostgreSQL. Table 35.48. sql_parts Columns Column Type Descrip…sql_parts sql_sizingManual ChaptersPG1835.51. sql_sizing The table sql_sizing contains information about various size limits and maximum values in PostgreSQL. This information is primarily intended for use in the context of the O…sql_sizing sqlcaManual ChaptersPG1834.8.2. sqlca For more powerful error handling, the embedded SQL interface provides a global variable with the name sqlca (SQL communication area) that has the following structure: struct { …sqlca SQLDA Data StructureManual ChaptersPG1834.7.2.1. SQLDA Data Structure SQLDA uses three data structure types: sqlda_t, sqlvar_t, and struct sqlname. Tip PostgreSQL's SQLDA has a similar data structure to the one in IBM DB2 Univers…SQLDA Data Structure SQLDA Descriptor AreasManual ChaptersPG1834.7.2. SQLDA Descriptor Areas An SQLDA Descriptor Area is a C language structure which can be also used to get the result set and the metadata of a query. One structure stores one record fr…SQLDA Descriptor Areas sqlda_t StructureManual ChaptersPG1834.7.2.1.1. sqlda_t Structure The structure type sqlda_t is the type of the actual SQLDA. It holds one record. And two or more sqlda_t structures can be connected in a linked list with the p…sqlda_t Structure SQLSTATE vs. SQLCODEManual ChaptersPG1834.8.3. SQLSTATE vs. SQLCODE The fields sqlca.sqlstate and sqlca.sqlcode are two different schemes that provide error codes. Both are derived from the SQL standard, but SQLCODE has been mark…SQLSTATE vs. SQLCODE sqlvar_t StructureManual ChaptersPG1834.7.2.1.2. sqlvar_t Structure The structure type sqlvar_t holds a column value and metadata such as type and length. The definition of the type is: struct sqlvar_struct { short sqltype; sho…sqlvar_t Structure SSLManual ChaptersPG1819.3.4. SSL See Section 18.9 for more information about setting up SSL. The configuration parameters for controlling transfer encryption using TLS protocols are named ssl for historic reason…SSL SSL Client File UsageManual ChaptersPG1832.19.4. SSL Client File Usage Table 32.2 summarizes the files that are relevant to the SSL setup on the client. Table 32.2. Libpq/Client SSL File Usage File Contents Effect ~/.postgresql/po…SSL Client File Usage SSL Library InitializationManual ChaptersPG1832.19.5. SSL Library Initialization Applications which need to be compatible with older versions of PostgreSQL, using OpenSSL version 1.0.2 or older, need to initialize the SSL library befor…SSL Library Initialization SSL Server File UsageManual ChaptersPG1818.9.4. SSL Server File Usage Table 18.2 summarizes the files that are relevant to the SSL setup on the server. (The shown file names are default names. The locally configured names could be…SSL Server File Usage SSL Session EncryptionManual ChaptersPG1854.2.10. SSL Session Encryption If PostgreSQL was built with SSL support, frontend/backend communications can be encrypted using SSL. This provides communication security in environments whe…SSL Session Encryption SSL SupportManual ChaptersPG1832.19. SSL Support PostgreSQL has native support for using SSL connections to encrypt client/server communications using TLS protocols for increased security. See Section 18.9 for details ab…SSL Support sslinfo — obtain client SSL informationManual ChaptersPG18F.42. sslinfo — obtain client SSL information The sslinfo module provides information about the SSL certificate that the current client provided when connecting to PostgreSQL. The module is …sslinfo — obtain client SSL information SSPI AuthenticationManual ChaptersPG1820.7. SSPI Authentication SSPI is a Windows technology for secure authentication with single sign-on. PostgreSQL will use SSPI in negotiate mode, which will use Kerberos when possible and au…SSPI Authentication Standalone Hot BackupsManual ChaptersPG1825.3.7.1. Standalone Hot Backups It is possible to use PostgreSQL's backup facilities to produce standalone hot backups. These are backups that cannot be used for point-in-time recovery, yet…Standalone Hot Backups Standard CollationsManual ChaptersPG1823.2.2.1. Standard Collations On all platforms, the following collations are supported: unicode This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unico…Standard Collations Standard Unix ToolsManual ChaptersPG1827.1. Standard Unix Tools On most Unix platforms, PostgreSQL modifies its command title as reported by ps, so that individual server processes can readily be identified. A sample display is …Standard Unix Tools Standby Server OperationManual ChaptersPG1826.2.2. Standby Server Operation A server enters standby mode if a standby.signal file exists in the data directory when the server is started. In standby mode, the server continuously appli…Standby Server Operation Standby ServersManual ChaptersPG1819.6.3. Standby Servers These settings control the behavior of a standby server that is to receive replication data. Their values on the primary server are irrelevant. primary_conninfo (stri…Standby Servers START TRANSACTIONManual ChaptersPG18START TRANSACTION START TRANSACTION — start a transaction block Synopsis START TRANSACTION [ transaction_mode [, ...] ] where transaction_mode is one of: ISOLATION LEVEL { SERIALIZABLE | REP…START TRANSACTION Start-upManual ChaptersPG1854.2.1. Start-up To begin a session, a frontend opens a connection to the server and sends a startup message. This message includes the names of the user and of the database the user wants t…Start-up Starting the Database ServerManual ChaptersPG1818.3. Starting the Database Server Before anyone can access the database, you must start the database server. The database server program is called postgres. If you are using a pre-packaged …Starting the Database Server Starting the ServerManual ChaptersPG18Starting the Server To start the server, waiting until the server is accepting connections: $ pg_ctl start To start the server using port 5433, and running without fsync, use: $ pg_ctl -o "-…Starting the Server Startup CallbackManual ChaptersPG1849.2.1. Startup Callback The startup_cb callback is called shortly after the module is loaded. This callback can be used to perform any additional initialization required. If the archive mod…Startup Callback Startup CallbackManual ChaptersPG1847.6.4.1. Startup Callback The optional startup_cb callback is called whenever a replication slot is created or asked to stream changes, independent of the number of changes that are ready t…Startup Callback Startup CallbackManual ChaptersPG1850.3.1. Startup Callback The startup_cb callback is executed directly after loading the module. This callback can be used to set up local state and perform additional initialization if requi…Startup Callback Statement BehaviorManual ChaptersPG1819.11.1. Statement Behavior client_min_messages (enum) Controls which message levels are sent to the client. Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, LOG, NOTICE, WARNING, an…Statement Behavior StatisticsManual ChaptersPG18F.17.5. Statistics The hstore type, because of its intrinsic liberality, could contain a lot of different keys. Checking for valid keys is the task of the application. The following examples…Statistics Statistics Collection ConfigurationManual ChaptersPG1827.2.1. Statistics Collection Configuration Since collection of statistics adds some overhead to query execution, the system can be configured to collect or not collect information. This is …Statistics Collection Configuration Statistics FunctionsManual ChaptersPG1827.2.26. Statistics Functions Other ways of looking at the statistics can be set up by writing queries that use the same underlying statistics access functions used by the standard views sho…Statistics Functions Statistics Information FunctionsManual ChaptersPG189.31. Statistics Information Functions PostgreSQL provides a function to inspect complex statistics defined using the CREATE STATISTICS command.Statistics Information Functions Statistics MonitoringManual ChaptersPG1819.9.2. Statistics Monitoring compute_query_id (enum) # Enables in-core computation of a query identifier. Query identifiers can be displayed in the pg_stat_activity view, using EXPLAIN, or …Statistics Monitoring