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OutputsManual ChaptersPG18Outputs When VERBOSE is specified, ANALYZE emits progress messages to indicate which table is currently being processed. Various statistics about the tables are printed as well.Outputs OutputsManual ChaptersPG18Outputs On successful completion, a COPY command returns a command tag of the form COPY count The count is the number of rows copied. Note psql will print this command tag only if the comman…Outputs OutputsManual ChaptersPG18Outputs On successful completion, a DELETE command returns a command tag of the form DELETE count The count is the number of rows deleted. Note that the number may be less than the number of…Outputs OutputsManual ChaptersPG18Outputs The command tag returned by EXECUTE is that of the prepared statement, and not EXECUTE.Outputs OutputsManual ChaptersPG18Outputs The command's result is a textual description of the plan selected for the statement, optionally annotated with execution statistics. Section 14.1 describes the information provided.Outputs OutputsManual ChaptersPG18Outputs On successful completion, a FETCH command returns a command tag of the form FETCH count The count is the number of rows fetched (possibly zero). Note that in psql, the command tag wi…Outputs OutputsManual ChaptersPG18Outputs On successful completion, an INSERT command returns a command tag of the form INSERT oid count The count is the number of rows inserted or updated. oid is always 0 (it used to be the…Outputs OutputsManual ChaptersPG18Outputs On successful completion, a MERGE command returns a command tag of the form MERGE total_count The total_count is the total number of rows changed (whether inserted, updated, or delet…Outputs OutputsManual ChaptersPG18Outputs On successful completion, a MOVE command returns a command tag of the form MOVE count The count is the number of rows that a FETCH command with the same parameters would have returne…Outputs OutputsManual ChaptersPG18Outputs On successful completion, an UPDATE command returns a command tag of the form UPDATE count The count is the number of rows updated, including matched rows whose values did not change…Outputs OutputsManual ChaptersPG18Outputs When VERBOSE is specified, VACUUM emits progress messages to indicate which table is currently being processed. Various statistics about the tables are printed as well.Outputs OverloadingManual ChaptersPG18Overloading PostgreSQL allows function overloading; that is, the same name can be used for several different functions so long as they have distinct input argument types. Whether or not you …Overloading OverviewManual ChaptersPG1852.1. Overview Table 52.1 lists the system catalogs. More detailed documentation of each catalog follows below. Most system catalogs are copied from the template database during database cre…Overview OverviewManual ChaptersPG185.12.1. Overview Partitioning refers to splitting what is logically one large table into smaller physical pieces. Partitioning can provide several benefits: Query performance can be improved…Overview OverviewManual ChaptersPG1834.4.1. Overview Passing data between the C program and the SQL statements is particularly simple in embedded SQL. Instead of having the program paste the data into the statement, which enta…Overview OverviewManual ChaptersPG1865.6.1. Overview PostgreSQL includes an implementation of persistent on-disk hash indexes, which are fully crash recoverable. Any data type can be indexed by a hash index, including data typ…Overview OverviewManual ChaptersPG1823.1.1. Overview Locale support is automatically initialized when a database cluster is created using initdb. initdb will initialize the database cluster with the locale setting of its execu…Overview OverviewManual ChaptersPG1847.8.1. Overview Logical decoding can be used to build synchronous replication solutions with the same user interface as synchronous replication for streaming replication. To do this, the st…Overview OverviewManual ChaptersPG1822.1. Overview A small number of objects, like role, database, and tablespace names, are defined at the cluster level and stored in the pg_global tablespace. Inside the cluster are multiple …Overview OverviewManual ChaptersPG18F.31.1. Overview pgrowlocks(text) returns setof record The parameter is the name of a table. The result is a set of records, with one row for each locked row within the table. The output col…Overview OverviewManual ChaptersPG1841.1. Overview PL/pgSQL is a loadable procedural language for the PostgreSQL database system. The design goals of PL/pgSQL were to create a loadable procedural language that can be used to c…Overview OverviewManual ChaptersPG1842.1. Overview PL/Tcl offers most of the capabilities a function writer has in the C language, with a few restrictions, and with the addition of the powerful string processing libraries that…Overview OverviewManual ChaptersPG1854.1. Overview The protocol has separate phases for startup and normal operation. In the startup phase, the frontend opens a connection to the server and authenticates itself to the satisfac…Overview OverviewManual ChaptersPG187.1. Overview The process of retrieving or the command to retrieve data from a database is called a query. In SQL the SELECT command is used to specify queries. The general syntax of the SEL…Overview OverviewManual ChaptersPG18E.6.1. Overview PostgreSQL 18 contains many new features and enhancements, including: An asynchronous I/O (AIO) subsystem that can improve performance of sequential scans, bitmap heap scans,…Overview OverviewManual ChaptersPG18F.40.1. Overview This module integrates with SELinux to provide an additional layer of security checking above and beyond what is normally provided by PostgreSQL. From the perspective of SEL…Overview OverviewManual ChaptersPG1810.1. Overview SQL is a strongly typed language. That is, every data item has an associated data type which determines its behavior and allowed usage. PostgreSQL has an extensible type syste…Overview OverviewManual ChaptersPG1853.1. Overview Table 53.1 lists the system views. More detailed documentation of each catalog follows below. Except where noted, all the views described here are read-only. Table 53.1. Syste…Overview Overview of Event Trigger BehaviorManual ChaptersPG1838.1. Overview of Event Trigger Behavior An event trigger fires whenever the event with which it is associated occurs in the database in which it is defined. Currently, the supported events …Overview of Event Trigger Behavior Overview of PostgreSQL InternalsManual ChaptersPG18Chapter 51. Overview of PostgreSQL Internals Author This chapter originated as part of [sim98] Stefan Simkovics' Master's Thesis prepared at Vienna University of Technology under the directi…Overview of PostgreSQL Internals Overview of Trigger BehaviorManual ChaptersPG1837.1. Overview of Trigger Behavior A trigger is a specification that the database should automatically execute a particular function whenever a certain type of operation is performed. Trigge…Overview of Trigger Behavior Packaging Related Objects into an ExtensionManual ChaptersPG1836.17. Packaging Related Objects into an Extension A useful extension to PostgreSQL typically includes multiple SQL objects; for example, a new data type will require new functions, new oper…Packaging Related Objects into an Extension Page-Level LocksManual ChaptersPG1813.3.3. Page-Level Locks In addition to table and row locks, page-level share/exclusive locks are used to control read/write access to table pages in the shared buffer pool. These locks are …Page-Level Locks pageinspect — low-level inspection of database pagesManual ChaptersPG18F.23. pageinspect — low-level inspection of database pages The pageinspect module provides functions that allow you to inspect the contents of database pages at a low level, which is useful …pageinspect — low-level inspection of database pages PAM AuthenticationManual ChaptersPG1820.13. PAM Authentication This authentication method operates similarly to password except that it uses PAM (Pluggable Authentication Modules) as the authentication mechanism. The default PA…PAM Authentication Parallel AggregationManual ChaptersPG1815.3.3. Parallel Aggregation PostgreSQL supports parallel aggregation by aggregating in two stages. First, each process participating in the parallel portion of the query performs an aggrega…Parallel Aggregation Parallel AppendManual ChaptersPG1815.3.4. Parallel Append Whenever PostgreSQL needs to combine rows from multiple sources into a single result set, it uses an Append or MergeAppend plan node. This commonly happens when imple…Parallel Append Parallel JoinsManual ChaptersPG1815.3.2. Parallel Joins Just as in a non-parallel plan, the driving table may be joined to one or more other tables using a nested loop, hash join, or merge join. The inner side of the join m…Parallel Joins Parallel Labeling for Functions and AggregatesManual ChaptersPG1815.4.1. Parallel Labeling for Functions and Aggregates The planner cannot automatically determine whether a user-defined function or aggregate is parallel safe, parallel restricted, or paral…Parallel Labeling for Functions and Aggregates Parallel Plan TipsManual ChaptersPG1815.3.5. Parallel Plan Tips If a query that is expected to do so does not produce a parallel plan, you can try reducing parallel_setup_cost or parallel_tuple_cost. Of course, this plan may tu…Parallel Plan Tips