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LISTENManual ChaptersPG18LISTEN LISTEN — listen for a notification Synopsis LISTEN channelLISTEN lo — manage large objectsManual ChaptersPG18F.21. lo — manage large objects The lo module provides support for managing Large Objects (also called LOs or BLOBs). This includes a data type lo and a trigger lo_manage. This module is con…lo — manage large objects LOADManual ChaptersPG18LOAD LOAD — load a shared library file Synopsis LOAD 'filename'LOAD Locale and EncodingManual ChaptersPG1831.1.4. Locale and Encoding By default, tests using a temporary installation use the locale defined in the current environment and the corresponding database encoding as determined by initdb…Locale and Encoding Locale and FormattingManual ChaptersPG1819.11.2. Locale and Formatting DateStyle (string) Sets the display format for date and time values, as well as the rules for interpreting ambiguous date input values. For historical reasons,…Locale and Formatting Locale Canonicalization and ValidationManual ChaptersPG1823.1.5.2. Locale Canonicalization and Validation When defining a new ICU collation object or database with ICU as the provider, the given locale name is transformed ("canonicalized") into a …Locale Canonicalization and Validation Locale DifferencesManual ChaptersPG1831.2.2. Locale Differences If you run the tests against a server that was initialized with a collation-order locale other than C, then there might be differences due to sort order and subseq…Locale Differences Locale ProvidersManual ChaptersPG1823.1.4. Locale Providers A locale provider specifies which library defines the locale behavior for collations and character classifications. The commands and tools that select the locale set…Locale Providers Locale SupportManual ChaptersPG1823.1. Locale Support Locale support refers to an application respecting cultural preferences regarding alphabets, sorting, number formatting, etc. PostgreSQL uses the standard ISO C and POSI…Locale Support LocalizationManual ChaptersPG18Chapter 23. Localization This chapter describes the available localization features from the point of view of the administrator. PostgreSQL supports two localization facilities: Using the lo…Localization LOCKManual ChaptersPG18LOCK LOCK — lock a table Synopsis LOCK [ TABLE ] [ ONLY ] name [ * ] [, ...] [ IN lockmode MODE ] [ NOWAIT ] where lockmode is one of: ACCESS SHARE | ROW SHARE | ROW EXCLUSIVE | SHARE UPDATE…LOCK Lock ManagementManual ChaptersPG1819.12. Lock Management deadlock_timeout (integer) # This is the amount of time to wait on a lock before checking to see if there is a deadlock condition. The check for deadlock is relatively…Lock Management Locking and IndexesManual ChaptersPG1813.7. Locking and Indexes Though PostgreSQL provides nonblocking read/write access to table data, nonblocking read/write access is not currently offered for every index access method impleme…Locking and Indexes Log File MaintenanceManual ChaptersPG1824.3. Log File Maintenance It is a good idea to save the database server's log output somewhere, rather than just discarding it via /dev/null. The log output is invaluable when diagnosing pr…Log File Maintenance Log-Shipping Standby ServersManual ChaptersPG1826.2. Log-Shipping Standby Servers Continuous archiving can be used to create a high availability (HA) cluster configuration with one or more standby servers ready to take over operations if…Log-Shipping Standby Servers Logical DecodingManual ChaptersPG1847.2.1. Logical Decoding Logical decoding is the process of extracting all persistent changes to a database's tables into a coherent, easy to understand format which can be interpreted witho…Logical Decoding Logical DecodingManual ChaptersPG18Chapter 47. Logical Decoding PostgreSQL provides infrastructure to stream the modifications performed via SQL to external consumers. This functionality can be used for a variety of purposes,…Logical Decoding Logical Decoding ConceptsManual ChaptersPG1847.2. Logical Decoding ConceptsLogical Decoding Concepts Logical Decoding ExamplesManual ChaptersPG1847.1. Logical Decoding Examples The following example demonstrates controlling logical decoding using the SQL interface. Before you can use logical decoding, you must set wal_level to logica…Logical Decoding Examples Logical Decoding Output PluginsManual ChaptersPG1847.6. Logical Decoding Output Plugins An example output plugin can be found in the contrib/test_decoding subdirectory of the PostgreSQL source tree.Logical Decoding Output Plugins Logical Decoding Output WritersManual ChaptersPG1847.7. Logical Decoding Output Writers It is possible to add more output methods for logical decoding. For details, see src/backend/replication/logical/logicalfuncs.c. Essentially, three func…Logical Decoding Output Writers Logical Decoding SQL InterfaceManual ChaptersPG1847.4. Logical Decoding SQL Interface See Section 9.28.6 for detailed documentation on the SQL-level API for interacting with logical decoding. Synchronous replication (see Section 26.2.8) is…Logical Decoding SQL Interface Logical OperatorsManual ChaptersPG189.1. Logical Operators The usual logical operators are available: boolean AND boolean → boolean boolean OR boolean → boolean NOT boolean → boolean SQL uses a three-valued logic system with t…Logical Operators Logical ReplicationManual ChaptersPG18Chapter 29. Logical Replication Logical replication is a method of replicating data objects and their changes, based upon their replication identity (usually a primary key). We use the term …Logical Replication Logical ReplicationManual ChaptersPG18E.6.3.1.8. Logical Replication Allow the values of generated columns to be logically replicated (Shubham Khanna, Vignesh C, Zhijie Hou, Shlok Kyal, Peter Smith) § § § § If the publication sp…Logical Replication Logical Replication ApplicationsManual ChaptersPG18E.6.3.7.3. Logical Replication Applications Add pg_createsubscriber option --all to create logical replicas for all databases (Shubham Khanna) § Add pg_createsubscriber option --clean to rem…Logical Replication Applications Logical Replication FailoverManual ChaptersPG1829.3. Logical Replication Failover To allow subscriber nodes to continue replicating data from the publisher node even when the publisher node goes down, there must be a physical standby cor…Logical Replication Failover Logical Replication Message FormatsManual ChaptersPG1854.9. Logical Replication Message Formats This section describes the detailed format of each logical replication message. These messages are either returned by the replication slot SQL inter…Logical Replication Message Formats Logical Replication Protocol Message FlowManual ChaptersPG1854.5.3. Logical Replication Protocol Message Flow With the exception of the START_REPLICATION command and the replay progress messages, all information flows only from the backend to the fro…Logical Replication Protocol Message Flow Logical Replication Protocol MessagesManual ChaptersPG1854.5.2. Logical Replication Protocol Messages The individual protocol messages are discussed in the following subsections. Individual messages are described in Section 54.9. All top-level pr…Logical Replication Protocol Messages Logical Streaming Replication ParametersManual ChaptersPG1854.5.1. Logical Streaming Replication Parameters Using the START_REPLICATION command, pgoutput accepts the following options: proto_version Protocol version. Currently versions 1, 2, 3, and …Logical Streaming Replication Parameters Logical Streaming Replication ProtocolManual ChaptersPG1854.5. Logical Streaming Replication Protocol This section describes the logical replication protocol, which is the message flow started by the START_REPLICATION SLOT slot_name LOGICAL replic…Logical Streaming Replication Protocol loginManual ChaptersPG1838.1.1. login The login event occurs when an authenticated user logs into the system. Any bug in a trigger procedure for this event may prevent successful login to the system. Such bugs may …login LOOPManual ChaptersPG1841.6.5.1. LOOP [ <<label>> ] LOOP statements END LOOP [ label ]; LOOP defines an unconditional loop that is repeated indefinitely until terminated by an EXIT or RETURN statement. The optiona…LOOP Looping through a Cursor's ResultManual ChaptersPG1841.7.4. Looping through a Cursor's Result There is a variant of the FOR statement that allows iterating through the rows returned by a cursor. The syntax is: [ <<label>> ] FOR recordvar IN b…Looping through a Cursor's Result Looping through ArraysManual ChaptersPG1841.6.7. Looping through Arrays The FOREACH loop is much like a FOR loop, but instead of iterating through the rows returned by an SQL query, it iterates through the elements of an array valu…Looping through Arrays Looping through Query ResultsManual ChaptersPG1841.6.6. Looping through Query Results Using a different type of FOR loop, you can iterate through the results of a query and manipulate that data accordingly. The syntax is: [ <<label>> ] FO…Looping through Query Results ltree — hierarchical tree-like data typeManual ChaptersPG18F.22. ltree — hierarchical tree-like data type This module implements a data type ltree for representing labels of data stored in a hierarchical tree-like structure. Extensive facilities for…ltree — hierarchical tree-like data type LWLocksManual ChaptersPG1836.10.12. LWLocksLWLocks macaddrManual ChaptersPG188.9.4. macaddr The macaddr type stores MAC addresses, known for example from Ethernet card hardware addresses (although MAC addresses are used for other purposes as well). Input is accepted …macaddr