On Thu, Apr 2, 2020 at 8:44 AM Jürgen Purtz <juer...@purtz.de> wrote:
> +1 and many thanks to Alvaros edits. > > I did some of the grunt work Alvaro alluded to in v6, and the results are attached and they build, which means there are no invalid links. Notes: * no definition wordings were changed * added a linkend to all remaining glossterms that do not immediately follow a glossentry * renamed id glossary-temporary-tables to glossary-temporary-table * temporarily re-added an id for glossary-row as we have many references to that. unsure if we should use the term Tuple in all those places or say Row while linking to glossary-tuple, or something else * temporarily re-added an id for glossary-segment, glossary-wal-segment, glossary-analytic-function, as those were also referenced and will need similar decisions made * added a stub entry for glossary-unique-index, unsure if it should have a definition on it's own, or we split it into unique and index. * I noticed several cases where a glossterm is used twice in a definition, but didn't de-term them * I'm curious about how we should tag a term when using it in its own definition. same as anywhere else?
From 4603ce04306e77f5508bb207b42e5dec1425e7c5 Mon Sep 17 00:00:00 2001 From: coreyhuinker <corey.huin...@gmail.com> Date: Thu, 2 Apr 2020 15:32:43 -0400 Subject: [PATCH] glossary v7 --- doc/src/sgml/filelist.sgml | 1 + doc/src/sgml/glossary.sgml | 1589 ++++++++++++++++++++++++++++++++++++ doc/src/sgml/postgres.sgml | 1 + 3 files changed, 1591 insertions(+) create mode 100644 doc/src/sgml/glossary.sgml diff --git a/doc/src/sgml/filelist.sgml b/doc/src/sgml/filelist.sgml index 1043d0f7ab..cf21ef857e 100644 --- a/doc/src/sgml/filelist.sgml +++ b/doc/src/sgml/filelist.sgml @@ -170,6 +170,7 @@ <!ENTITY limits SYSTEM "limits.sgml"> <!ENTITY acronyms SYSTEM "acronyms.sgml"> +<!ENTITY glossary SYSTEM "glossary.sgml"> <!ENTITY color SYSTEM "color.sgml"> <!ENTITY features-supported SYSTEM "features-supported.sgml"> diff --git a/doc/src/sgml/glossary.sgml b/doc/src/sgml/glossary.sgml new file mode 100644 index 0000000000..edfcf9d725 --- /dev/null +++ b/doc/src/sgml/glossary.sgml @@ -0,0 +1,1589 @@ +<appendix id="glossary"> + <title>Glossary</title> + <para> + This is a list of terms and their meaning in the context of + <productname>PostgreSQL</productname> and relational database + systems in general. + </para> + + <glosslist> + <glossentry id="glossary-aggregate"> + <glossterm>Aggregate Function</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-function">function</glossterm> that + combines (<firstterm>aggregates</firstterm>) multiple input values, + for example by counting, averaging or adding, + yielding a single output value. + </para> + <para> + For more information, see + <xref linkend="functions-aggregate"/>. + </para> + <glossseealso otherterm="glossary-window-function" /> + </glossdef> + </glossentry> + + <glossentry id="glossary-analyze"> + <glossterm>Analyze (operation)</glossterm> + <glossdef> + <para> + The process of collecting statistics from data in + <glossterm linkend="glossary-table">tables</glossterm> + and other <glossterm linkend="glossary-relation">relations</glossterm> + to help the <glossterm linkend="glossary-planner">query planner</glossterm> + to make decisions about how to execute + <glossterm linkend="glossary-query">queries</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-analytic-function"> + <glossterm>Analytic Function</glossterm> + <glosssee otherterm="glossary-window-function" /> + </glossentry> + + <glossentry id="glossary-atomic"> + <glossterm>Atomic</glossterm> + <glossdef> + <para> + In reference to a <glossterm linkend="glossary-datum">datum</glossterm>: + the fact that its value that cannot be broken down into smaller + components. + </para> + </glossdef> + <glossdef> + <para> + In reference to a + <glossterm linkend="glossary-transaction">database transaction</glossterm>: + see <glossterm linkend="glossary-atomicity">atomicity</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-atomicity"> + <glossterm>Atomicity</glossterm> + <glossdef> + <para> + The property of a <glossterm linkend="glossary-transaction">transaction</glossterm> + that either all its operations complete as a single unit or none do. + This is one of the <acronym>ACID</acronym> properties. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-attribute"> + <glossterm>Attribute</glossterm> + <glossdef> + <para> + An element with a certain name and data type found within a + <glossterm linkend="glossary-tuple">tuple</glossterm> or + <glossterm linkend="glossary-table">table</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-autovacuum"> + <glossterm>Autovacuum</glossterm> + <glossdef> + <para> + Background processes that routinely perform + <glossterm linkend="glossary-vacuum">Vacuum</glossterm> and <glossterm linkend="glossary-analyze">Analyze</glossterm> + operations. + </para> + <para> + For more information, see + <xref linkend="routine-vacuuming"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-backend"> + <glossterm>Backend (process)</glossterm> + <glossdef> + <para> + Processes of an <glossterm linkend="glossary-instance">Instance</glossterm> which act on behalf of + client <glossterm linkend="glossary-connection">Connection</glossterm>s and handle their requests. + </para> + <para> + (Don't confuse this term with the similar terms + <glossterm linkend="glossary-background-worker">Background Worker</glossterm> or + <glossterm linkend="glossary-background-writer">Background Writer</glossterm>). + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-background-worker"> + <glossterm>Background Worker (process)</glossterm> + <glossdef> + <para> + Individual processes within an <glossterm linkend="glossary-instance">Instance</glossterm>, which + run system- or user-supplied code. A typical use case is a process + which handles parts of an <acronym>SQL</acronym> query to take + advantage of parallel execution on servers with multiple + <acronym>CPU</acronym>s. + </para> + <para> + For more information, see + <xref linkend="bgworker"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-background-writer"> + <glossterm>Background Writer (process)</glossterm> + <glossdef> + <para> + A process that continuously writes dirty pages from + <glossterm linkend="glossary-shared-memory">Shared Memory</glossterm> to the file system. + It wakes up periodically, but + works only for a short period in order to distribute its expensive + <acronym>I/O</acronym> activity over time, instead of generating fewer + larger <acronym>I/O</acronym> peaks which could block other processes. + </para> + <para> + For more information, see + <xref linkend="runtime-config-resource"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-cast"> + <glossterm>Cast</glossterm> + <glossdef> + <para> + A conversion of a <glossterm linkend="glossary-cast">Datum</glossterm> from its current data + type to another data type. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-catalog"> + <glossterm>Catalog</glossterm> + <glossdef> + <para> + The <acronym>SQL</acronym> standard uses this term to + indicate what is called a <glossterm linkend="glossary-database">Database</glossterm> in + <productname>PostgreSQL</productname>'s terminology. + </para> + <para> + This should not be confused with the + <glossterm linkend="glossary-system-catalog">System Catalog</glossterm>. + </para> + <para> + For more information, see + <xref linkend="manage-ag-overview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-check-constraint"> + <glossterm>Check Constraint</glossterm> + <glossdef> + <para> + A type of <glossterm linkend="glossary-constraint">Constraint</glossterm> defined on a + <glossterm linkend="glossary-relation">Relation</glossterm> which restricts the values allowed in + one or more <glossterm linkend="glossary-attribute">Attribute</glossterm>s. The + <glossterm linkend="glossary-check-constraint">Check Constraint</glossterm> can make reference to any + attribute in the <glossterm linkend="glossary-relation">Relation</glossterm>, but cannot reference + other <glossterm linkend="glossary-row">Row</glossterm>s of the same + relation or other relations. + </para> + <para> + For more information, see + <xref linkend="ddl-constraints"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-checkpointer"> + <glossterm>Checkpointer (process)</glossterm> + <glossdef> + <para> + A process that writes dirty pages to the file system and creates a special + checkpoint WAL record. This process is initiated when predefined + conditions are met, such as a specified amount of time has passed, or + a certain volume of records has been written. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-checkpoint"> + <glossterm>Checkpoint</glossterm> + <glossdef> + <para> + A point in time when all older dirty pages of the + <glossterm linkend="glossary-shared-memory">Shared Memory</glossterm>, all older <glossterm linkend="glossary-wal-record">WAL Record</glossterm>s, + and a special <firstterm>Checkpoint record</firstterm> + have been written and flushed to disk. + </para> + <para> + For more information, see + <xref linkend="sql-checkpoint"/>. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Class</glossterm> + <glosssee otherterm="glossary-relation" /> + </glossentry> + + <glossentry id="glossary-cluster"> + <glossterm>Cluster</glossterm> + <glossdef> + <para> + A group of <glossterm linkend="glossary-database">Database</glossterm>s plus their + <glossterm linkend="glossary-global-sql-object">Global SQL Object</glossterm>s. The + <glossterm linkend="glossary-cluster">Cluster</glossterm> is managed by exactly one + <glossterm linkend="glossary-instance">Instance</glossterm>. A newly created + <glossterm linkend="glossary-cluster">Cluster</glossterm> will have three + <glossterm linkend="glossary-database">Database</glossterm>s created automatically. They are + <literal>template0</literal>, <literal>template1</literal>, and + <literal>postgres</literal>. It is expected that an application will + create one or more additional <glossterm linkend="glossary-database">Database</glossterm>s aside + from these three. + </para> + <para> + Don't confuse the <productname>PostgreSQL</productname>-specific term + <glossterm linkend="glossary-cluster">Cluster</glossterm> with the SQL command + <literal>CLUSTER</literal>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-column"> + <glossterm>Column</glossterm> + <glossdef> + <para> + An <glossterm linkend="glossary-attribute">Attribute</glossterm> found in a + <glossterm linkend="glossary-table">Table</glossterm> or <glossterm linkend="glossary-view">View</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-commit"> + <glossterm>Commit</glossterm> + <glossdef> + <para> + The act of finalizing a <glossterm linkend="glossary-transaction">transaction</glossterm> + within the <glossterm linkend="glossary-database">Database</glossterm>, which makes it visible to other + transactions and assures its + <glossterm linkend="glossary-durability">durability</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-commit"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-concurrency"> + <glossterm>Concurrency</glossterm> + <glossdef> + <para> + The concept that multiple independent operations happen within the + <glossterm linkend="glossary-database">Database</glossterm> at the same time. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-connection"> + <glossterm>Connection</glossterm> + <glossdef> + <para> + An established line of communication between a client process + and a <glossterm linkend="glossary-backend">backend</glossterm>, + usually over a network. + </para> + <para> + For more information, see + <xref linkend="runtime-config-connection"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-consistency"> + <glossterm>Consistency</glossterm> + <glossdef> + <para> + The property that the data in the <glossterm linkend="glossary-database">database</glossterm> + is always in compliance with its own rules such as <glossterm linkend="glossary-table">Table</glossterm> + structure, <glossterm linkend="glossary-constraint">Constraint</glossterm>s, + <glossterm linkend="glossary-unique">uniqueness</glossterm>, etc. + This is one of the <acronym>ACID</acronym> properties. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-constraint"> + <glossterm>Constraint</glossterm> + <glossdef> + <para> + A restriction on the values of data allowed within a + <glossterm linkend="glossary-table">Table</glossterm>. + </para> + <para> + For more information, see + <xref linkend="ddl-constraints"/>. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Data Area</glossterm> + <glosssee otherterm="glossary-data-directory" /> + </glossentry> + + <glossentry id="glossary-data-directory"> + <glossterm>Data Directory</glossterm> + <glossdef> + <para> + The base directory on the filesystem of a + <glossterm linkend="glossary-server">Server</glossterm> that contains all data files and + subdirectories associated with a <glossterm linkend="glossary-cluster">Cluster</glossterm> with + the exception of <glossterm linkend="glossary-tablespace">Tablespace</glossterm>s. The environment + variable <literal>PGDATA</literal> often — but not always — + refers to the <glossterm linkend="glossary-data-directory">Data Directory</glossterm>. + </para> + <para> + For more information, see + <xref linkend="storage-file-layout"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-database"> + <glossterm>Database</glossterm> + <glossdef> + <para> + A named collection of <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s. + </para> + <para> + For more information, see + <xref linkend="manage-ag-overview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Database Server</glossterm> + <glosssee otherterm="glossary-instance" /> + </glossentry> + + <glossentry id="glossary-datum"> + <glossterm>Datum</glossterm> + <glossdef> + <para> + The internal representation of one value of a <acronym>SQL</acronym> + data type. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-delete"> + <glossterm>Delete</glossterm> + <glossdef> + <para> + A <acronym>SQL</acronym> command which removes + <glossterm linkend="glossary-row">Row</glossterm>s from a given <glossterm linkend="glossary-table">Table</glossterm> + or <glossterm linkend="glossary-relation">Relation</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-delete"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-durability"> + <glossterm>Durability</glossterm> + <glossdef> + <para> + The assurance that once a <glossterm linkend="glossary-transaction">transaction</glossterm> + has been <glossterm linkend="glossary-commit">Committed</glossterm>, the changes remain even after + a system failure or crash. + This is one of the <acronym>ACID</acronym> properties. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-file-segment"> + <glossterm>File Segment</glossterm> + <glossdef> + <para> + A physical file which stores data for a given + <glossterm linkend="glossary-heap">Heap</glossterm> or <glossterm linkend="glossary-index">Index</glossterm> object. + <glossterm linkend="glossary-file-segment">File Segment</glossterm>s are limited in size by a + configuration value and if that size is exceeded, it will be split + into multiple physical files. + </para> + <para> + For more information, see + <xref linkend="storage-file-layout"/>. + </para> + <para> + (Don't confuse this term with the similar term + <glossterm linkend="glossary-wal-segment">WAL Segment</glossterm>). + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-foreign-data-wrapper"> + <glossterm>Foreign Data Wrapper</glossterm> + <glossdef> + <para> + A means of representing data that is not contained in the local + <glossterm linkend="glossary-database">Database</glossterm> so that it appears as if were in local + <glossterm linkend="glossary-table">Table</glossterm>(s). With a Foreign Data Wrapper it is + possible to define a <glossterm linkend="glossary-foreign-server">Foreign Server</glossterm> and + <glossterm linkend="glossary-foreign-table">Foreign Table</glossterm>s. + </para> + <para> + For more information, see + <xref linkend="sql-createforeigndatawrapper"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-foreign-key"> + <glossterm>Foreign Key</glossterm> + <glossdef> + <para> + A type of <glossterm linkend="glossary-constraint">Constraint</glossterm> defined on one or more + <glossterm linkend="glossary-column">Column</glossterm>s in a <glossterm linkend="glossary-table">Table</glossterm> which + requires the value(s) in those <glossterm linkend="glossary-column">Column</glossterm>s to + identify exactly one <glossterm linkend="glossary-row">Row</glossterm> in another (or the same) + <glossterm linkend="glossary-table">Table</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-foreign-server"> + <glossterm>Foreign Server</glossterm> + <glossdef> + <para> + A named collection of <glossterm linkend="glossary-foreign-table">Foreign Table</glossterm>s which all + use the same <glossterm linkend="glossary-foreign-data-wrapper">Foreign Data Wrapper</glossterm> and have + other configuration values in common. + </para> + <para> + For more information, see + <xref linkend="sql-createserver"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-foreign-table"> + <glossterm>Foreign Table</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-relation">Relation</glossterm> which appears to have + <glossterm linkend="glossary-row">Row</glossterm>s and <glossterm linkend="glossary-column">Column</glossterm>s similar + to a regular <glossterm linkend="glossary-table">Table</glossterm>, but will forward requests + for data through its <glossterm linkend="glossary-foreign-data-wrapper">Foreign Data Wrapper</glossterm>, + which will return <glossterm linkend="glossary-result-set">Result Set</glossterm>s structured + according to the definition of the <glossterm linkend="glossary-foreign-table">Foreign Table</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-createforeigntable"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-function"> + <glossterm>Function</glossterm> + <glossdef> + <para> + Any defined transformation of data. Many functions are already defined + within <productname>PostgreSQL</productname> itself, but user-defined + ones can also be added. + </para> + <para> + For more information, see + <xref linkend="sql-createfunction"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-global-sql-object"> + <glossterm>Global SQL Object</glossterm> + <glossdef> + <para> + <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s which do not belong to a specific + <glossterm linkend="glossary-schema">Schema</glossterm>. + </para> + <para> + Objects that exist at the <glossterm linkend="glossary-database">Database</glossterm> level + include Extensions such as + <glossterm linkend="glossary-foreign-data-wrapper">Foreign Data Wrapper</glossterm>s. + </para> + <para> + Objects that exist at the <glossterm linkend="glossary-cluster">Cluster</glossterm> level + include <glossterm linkend="glossary-role">Role</glossterm>s, + <glossterm linkend="glossary-tablespace">Tablespace</glossterm>s, + <glossterm linkend="glossary-replication">Replication</glossterm> origins, and subscriptions + for logical replication. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-grant"> + <glossterm>Grant</glossterm> + <glossdef> + <para> + A <acronym>SQL</acronym> command that is used to allow + <glossterm linkend="glossary-user">User</glossterm>s or <glossterm linkend="glossary-role">Role</glossterm>s to access + specific objects within the <glossterm linkend="glossary-database">Database</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-grant"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-heap"> + <glossterm>Heap</glossterm> + <glossdef> + <para> + Contains the values of <glossterm linkend="glossary-row">Row</glossterm> attributes + (i.e. the data). The <glossterm linkend="glossary-heap">Heap</glossterm> is realized within + <glossterm linkend="glossary-database">Database</glossterm> files. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Host</glossterm> + <glosssee otherterm="glossary-server" /> + </glossentry> + + <glossentry id="glossary-index"> + <glossterm>Index</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-relation">Relation</glossterm> that contains data derived from a + <glossterm linkend="glossary-table">Table</glossterm> (or <glossterm linkend="glossary-relation">Relation</glossterm> types + such as a <glossterm linkend="glossary-materialized-view">Materialized View</glossterm>). Its internal + structure supports fast retrieval of and access to the original + data. + </para> + <para> + For more information, see + <xref linkend="sql-createindex"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-insert"> + <glossterm>Insert</glossterm> + <glossdef> + <para> + A <acronym>SQL</acronym> command used to add new data into a + <glossterm linkend="glossary-table">Table</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-insert"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-instance"> + <glossterm>Instance</glossterm> + <glossdef> + <para> + An <glossterm linkend="glossary-instance">Instance</glossterm> is a group of processes plus their + common <glossterm linkend="glossary-shared-memory">Shared Memory</glossterm> running on a single + <glossterm linkend="glossary-server">Server</glossterm>. The <glossterm linkend="glossary-instance">Instance</glossterm> + handles all key features of a <acronym>DBMS</acronym>: read and write + access to files and shared memory, assurance of + the <acronym>ACID</acronym> paradigm, <acronym>MVCC</acronym>, + <glossterm linkend="glossary-connection">Connection</glossterm>s to client programs, backup, + recovery, replication, privileges, etc. + </para> + <para> + An <glossterm linkend="glossary-instance">Instance</glossterm> manages exactly one + <glossterm linkend="glossary-cluster">Cluster</glossterm>. + </para> + <para> + Many <glossterm linkend="glossary-instance">Instance</glossterm>s can run on the same server as + long as their <acronym>TCP/IP</acronym> ports do not conflict. + Different instances on a server may use the + same or different versions of <productname>PostgreSQL</productname>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-isolation"> + <glossterm>Isolation</glossterm> + <glossdef> + <para> + The property that the effects of a transaction are not visible to + <glossterm linkend="glossary-concurrency">concurrent transactions</glossterm> + before it commits. + This is one of the <acronym>ACID</acronym> properties. + </para> + <para> + For more information, see <xref linkend="transaction-iso" />. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-join"> + <glossterm>Join</glossterm> + <glossdef> + <para> + A <acronym>SQL</acronym> keyword used in <command>SELECT</command> statements for + combining data from multiple <glossterm linkend="glossary-relation">Relation</glossterm>s. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-key"> + <glossterm>Key</glossterm> + <glossdef> + <para> + A means of identifying a <glossterm linkend="glossary-row">Row</glossterm> within a + <glossterm linkend="glossary-table">Table</glossterm> or <glossterm linkend="glossary-relation">Relation</glossterm> by + values contained within one or more <glossterm linkend="glossary-attribute">Attribute</glossterm>s + in that <glossterm linkend="glossary-table">Table</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-lock"> + <glossterm>Lock</glossterm> + <glossdef> + <para> + A mechanism that allows a process to limit or prevent simultaneous + access to a resource. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-log-file"> + <glossterm>Log File</glossterm> + <glossdef> + <para> + <glossterm>Log File</glossterm>s contain human-readable text lines about + events. Examples include login failures, long-running queries, etc. + </para> + <para> + For more information, see + <xref linkend="logfile-maintenance"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-logger"> + <glossterm>Logger (process)</glossterm> + <glossdef> + <para> + If activated, the + <glossterm linkend="glossary-logger">Logger</glossterm> process + writes information about database events into the current + <glossterm linkend="glossary-log-file">Log File</glossterm>. When reaching certain time- or + volume-dependent criteria, a new log file is created. + Also called <firstterm>syslogger</firstterm>. + </para> + <para> + For more information, see + <xref linkend="runtime-config-logging"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-log-record"> + <glossterm>Log Record</glossterm> + <glossdef> + <para> + Archaic term for a <glossterm linkend="glossary-wal-record">WAL Record</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-logged"> + <glossterm>Logged</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-table">Table</glossterm> is considered + <glossterm linkend="glossary-logged">Logged</glossterm> if changes to it are sent to the + <glossterm linkend="glossary-wal">WAL Log</glossterm>. By default, all regular + <glossterm linkend="glossary-table">Table</glossterm>s are <glossterm linkend="glossary-logged">Logged</glossterm>. A + table can be specified as <glossterm linkend="glossary-unlogged">Unlogged</glossterm> either at + creation time or via the <command>ALTER TABLE</command> command. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Master (server)</glossterm> + <glosssee otherterm="glossary-primary-server" /> + </glossentry> + + <glossentry id="glossary-materialized"> + <glossterm>Materialized</glossterm> + <glossdef> + <para> + The act of storing information rather than just the method of accessing + the information. This term is used in <glossterm linkend="glossary-materialized-view">Materialized + View</glossterm>s, meaning that the data derived from the + <glossterm linkend="glossary-view">View</glossterm> is actually stored on disk separately from + the sources of that data. When using the term + <glossterm linkend="glossary-materialized">Materialized</glossterm> to refer to + multi-step queries, it means that the data of a given step is stored + in memory, but that storage may spill over onto disk. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-materialized-view"> + <glossterm>Materialized View</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-relation">Relation</glossterm> that is defined in the same way that + a <glossterm linkend="glossary-view">View</glossterm> is, but stores data in the same way + that a <glossterm linkend="glossary-table">Table</glossterm> does. It cannot be modified via + <command>INSERT</command>, <command>UPDATE</command>, or + <command>DELETE</command> operations. + </para> + <para> + For more information, see + <xref linkend="sql-creatematerializedview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-null"> + <glossterm>Null</glossterm> + <glossdef> + <para> + A concept of non-existence that is a central tenet of Relational + Database Theory. It represents the absence of value. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>Optimizer</glossterm> + <glosssee otherterm="glossary-planner" /> + </glossentry> + + <glossentry id="glossary-partition"> + <glossterm>Partition</glossterm> + <glossdef> + <para> + In reference to a <glossterm linkend="glossary-table">Table</glossterm>: + A <glossterm linkend="glossary-table">Table</glossterm> that can be queried directly, + or via a partitioned table, which is a collection of + sub-tables, each capable of holding one defined + subset of information that does not overlap with any other + table in the collection. + </para> + <para> + In reference to a <glossterm linkend="glossary-analytic-function">Analytic Function</glossterm>: + a partition is a definition that identifies which neighboring + <glossterm linkend="glossary-row">Row</glossterm>s can be considered by the + function. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-postmaster"> + <glossterm>Postmaster (process)</glossterm> + <glossdef> + <para> + The very first process of an <glossterm linkend="glossary-instance">Instance</glossterm>. It + starts and manages the other auxiliary processes and creates + <glossterm linkend="glossary-backend">backend processes</glossterm> + on demand. + </para> + <para> + For more information, see + <xref linkend="server-start"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-primary-server"> + <glossterm>Primary (server)</glossterm> + <glossdef> + <para> + When two or more <glossterm linkend="glossary-database">Database</glossterm>s are linked via + <glossterm linkend="glossary-replication">Replication</glossterm>, the <glossterm linkend="glossary-server">Server</glossterm> + that is considered the authoritative source of information is called + the <firstterm>Primary</firstterm>, + also known as a <firstterm>master</firstterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-primary-key"> + <glossterm>Primary Key</glossterm> + <glossdef> + <para> + A special case of a <glossterm linkend="glossary-unique-index">Unique Index</glossterm> defined on a + <glossterm linkend="glossary-table">Table</glossterm> or other <glossterm linkend="glossary-relation">Relation</glossterm> + that also guarantees that all of the <glossterm linkend="glossary-attribute">Attribute</glossterm>s + within the <glossterm linkend="glossary-primary-key">Primary Key</glossterm> do not have + <glossterm linkend="glossary-null">Null</glossterm> values. As the name implies, there can be + only one <glossterm linkend="glossary-primary-key">Primary Key</glossterm> per + table, though it is possible to have multiple + unique indexes that also have no null-capable attributes. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-procedure"> + <glossterm>Procedure</glossterm> + <glossdef> + <para> + A defined set of instructions for manipulating data within a + <glossterm linkend="glossary-database">Database</glossterm>. A <glossterm linkend="glossary-procedure">Procedure</glossterm> can + be written in a variety of programming languages. They may seem + similar to <glossterm linkend="glossary-function">Function</glossterm>s, but are different in that + they must be invoked via the <command>CALL</command> command rather + than the <command>SELECT</command> or <command>PERFORM</command> + commands, and they are allowed to make transactional statements such + as <command>COMMIT</command> and <command>ROLLBACK</command>. + </para> + <para> + For more information, see + <xref linkend="sql-createprocedure"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-query"> + <glossterm>Query</glossterm> + <glossdef> + <para> + A request sent by a client to a <glossterm linkend="glossary-backend">backend</glossterm>, + usually to return results or to modify data on the database. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-planner"> + <glossterm>Query Planner</glossterm> + <glossdef> + <para> + The part of <productname>PostgreSQL</productname> that is devoted to + determining (<firstterm>planning</firstterm>) the most efficient way to + execute <glossterm linkend="glossary-query">queries</glossterm>. + Also known as <firstterm>query optimizer</firstterm>, + <firstterm>optimizer</firstterm>, or simply <firstterm>planner</firstterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-record"> + <glossterm>Record</glossterm> + <glosssee otherterm="glossary-tuple" /> + </glossentry> + + <glossentry> + <glossterm>Recycling</glossterm> + <glosssee otherterm="glossary-wal-file" /> + </glossentry> + + <glossentry id="glossary-referential-integrity"> + <glossterm>Referential Integrity</glossterm> + <glossdef> + <para> + A means of restricting data in one <glossterm linkend="glossary-relation">Relation</glossterm> + by a <glossterm linkend="glossary-foreign-key">Foreign Key</glossterm> + so that it must have matching data in another + <glossterm linkend="glossary-relation">Relation</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-relation"> + <glossterm>Relation</glossterm> + <glossdef> + <para> + The generic term for all objects in a <glossterm linkend="glossary-database">Database</glossterm> + that have a name and a list of <glossterm linkend="glossary-attribute">Attribute</glossterm>s + defined in a specific order. <glossterm linkend="glossary-table">Table</glossterm>s, + <glossterm linkend="glossary-view">View</glossterm>s, <glossterm linkend="glossary-foreign-table">Foreign Table</glossterm>s, + <glossterm linkend="glossary-materialized-view">Materialized View</glossterm>s, and + <glossterm linkend="glossary-index">Index</glossterm>es are all relations. + </para> + <para> + <firstterm>Class</firstterm> is an archaic synonym for + <firstterm>relation</firstterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-replica"> + <glossterm>Replica</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-database">Database</glossterm> that is paired with a + <glossterm linkend="glossary-primary-server">primary</glossterm> + database and is maintaining a copy of some or + all of the primary <glossterm linkend="glossary-database">Database</glossterm>'s data. The foremost + reasons for doing this are to allow for greater access to that data, + and to maintain availability of the data in the event that the + <glossterm linkend="glossary-primary-server">primary</glossterm> becomes unavailable. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-replication"> + <glossterm>Replication</glossterm> + <glossdef> + <para> + The act of reproducing data on one <glossterm linkend="glossary-server">Server</glossterm> onto + another server called a <glossterm linkend="glossary-replica">Replica</glossterm>. This can take the + form of <firstterm>physical replication</firstterm>, where all file + changes from one server are copied verbatim, + or <firstterm>logical replication</firstterm> where a defined subset + of data changes are conveyed using a higher-level representation. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-result-set"> + <glossterm>Result Set</glossterm> + <glossdef> + <para> + A data structure transmitted from a <glossterm linkend="glossary-backend">Backend Process</glossterm> to + client program upon the completion of a <acronym>SQL</acronym> + command, usually a <command>SELECT</command> but it can be an + <command>INSERT</command>, <command>UPDATE</command>, or + <command>DELETE</command> command if the <literal>RETURNING</literal> + clause is specified. The data structure consists of zero or more + <glossterm linkend="glossary-row">Row</glossterm>s with the same ordered set of + <glossterm linkend="glossary-attribute">Attribute</glossterm>s. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-revoke"> + <glossterm>Revoke</glossterm> + <glossdef> + <para> + A command to prevent access to a named set of + <glossterm linkend="glossary-database">Database</glossterm> objects for a named list of + <glossterm linkend="glossary-user">User</glossterm>s and <glossterm linkend="glossary-role">Role</glossterm>s. + </para> + <para> + For more information, see + <xref linkend="sql-revoke"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-role"> + <glossterm>Role</glossterm> + <glossdef> + <para> + A collection of access privileges to the + <glossterm linkend="glossary-database">Database</glossterm>. <glossterm linkend="glossary-role">Role</glossterm>s are + themselves a privilege that can be granted to other roles. This is + often done for convenience or to ensure completeness when multiple + <glossterm linkend="glossary-user">User</glossterm>s need the same privileges. + </para> + <para> + For more information, see + <xref linkend="sql-createrole"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-rollback"> + <glossterm>Rollback</glossterm> + <glossdef> + <para> + A command to undo all of the operations performed since the beginning + of a <glossterm linkend="glossary-transaction">Transaction</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-rollback"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-row"> + <glossterm>Row</glossterm> + <glosssee otherterm="glossary-tuple" /> + </glossentry> + + <glossentry id="glossary-savepoint"> + <glossterm>Savepoint</glossterm> + <glossdef> + <para> + A special mark inside the sequence of steps in a + <glossterm linkend="glossary-transaction">Transaction</glossterm>. Data modifications after this + point in time may be reverted to the time of the savepoint. + </para> + <para> + For more information, see + <xref linkend="sql-savepoint"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-schema"> + <glossterm>Schema</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-schema">Schema</glossterm> is a namespace for + <glossterm linkend="glossary-sql-object">SQL object</glossterm>s, which all reside in the same + <glossterm linkend="glossary-database">database</glossterm>. Each + <glossterm linkend="glossary-sql-object">SQL object</glossterm> must reside in exactly one + <glossterm linkend="glossary-schema">Schema</glossterm>. + </para> + <para> + In general, the names of <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s in the + schema are unique — even across different types of objects. The lone + exception is the case of <glossterm linkend="glossary-unique">Unique</glossterm> + <glossterm linkend="glossary-constraint">Constraint</glossterm>s, in which case there + <emphasis>must</emphasis> be a <glossterm linkend="glossary-unique-index">Unique Index</glossterm> + with the same name and <glossterm linkend="glossary-schema">Schema</glossterm> as the + <glossterm linkend="glossary-constraint">Constraint</glossterm>. There is no restriction on reusing + a name in multiple <glossterm linkend="glossary-schema">Schema</glossterm>s. + </para> + <para> + Many <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s reside in the default + <glossterm linkend="glossary-schema">Schema</glossterm> <literal>public</literal>, but it is + expected that more schemas are created to hold application-specific + <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s. + </para> + <para> + More generically, the term <glossterm linkend="glossary-schema">Schema</glossterm> is used to + mean all data descriptions (<glossterm linkend="glossary-table">Table</glossterm> definitions, + <glossterm linkend="glossary-constraint">Constraint</glossterm>s, comments) for a given + <glossterm linkend="glossary-database">Database</glossterm>. + </para> + <para> + For more information, see + <xref linkend="ddl-schemas"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-segment"> + <glossterm linkend="glossary-segment">Segment</glossterm> + <glosssee otherterm="glossary-file-segment" /> + </glossentry> + + <glossentry id="glossary-select"> + <glossterm>Select</glossterm> + <glossdef> + <para> + The <acronym>SQL</acronym> command used to query a <glossterm linkend="glossary-database">Database</glossterm>. + Normally, <command>SELECT</command>s are not expected to modify the + <glossterm linkend="glossary-database">Database</glossterm> in any way, but it is possible that + <glossterm linkend="glossary-function">Function</glossterm>s invoked within the query could have + side effects that do modify data. + </para> + <para> + For more information, see + <xref linkend="sql-select"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-serializable"> + <glossterm>Serializable</glossterm> + <glossdef> + <para> + Transactions defined as <literal>SERIALIZABLE</literal> are unable to + see changes made within other transactions. In effect, for the + initializing session the entire <glossterm linkend="glossary-database">Database</glossterm> + appears to be frozen for the duration of the + <glossterm linkend="glossary-transaction">Transaction</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-server"> + <glossterm>Server</glossterm> + <glossdef> + <para> + A computer on which <productname>PostgreSQL</productname> + <glossterm linkend="glossary-instance">instances</glossterm> run. + The term <firstterm>server</firstterm> denotes real hardware, a + container, or a Virtual Machine. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-session"> + <glossterm>Session</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-connection">Connection</glossterm> to the <glossterm linkend="glossary-database">Database</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-sequence"> + <glossterm>Sequence</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-database">Database</glossterm> object which represents the + mathematical concept of a numerical integral sequence. It can be + thought of as a <glossterm linkend="glossary-table">Table</glossterm> with exactly one + <glossterm linkend="glossary-row">Row</glossterm> and one <glossterm linkend="glossary-column">Column</glossterm>. The + value stored is known as the current value. A + <glossterm linkend="glossary-sequence">Sequence</glossterm> has a defined direction (usually + increasing) and an interval step (usually 1). Whenever the + <literal>NEXTVAL</literal> pseudo-column of a + <glossterm linkend="glossary-sequence">Sequence</glossterm> is accessed, the current value is moved + in the defined direction by the defined interval step, that value + is returned to the invoking query, and the current value of the + sequence is updated to reflect the new value. The value can be updated + multiple times in a single query, the net effect being that each row + selected will have a different value. Values taken from a + <glossterm linkend="glossary-sequence">Sequence</glossterm> are never reverted, even in the case of + a <glossterm linkend="glossary-rollback">Rollback</glossterm>, which means that the + <glossterm linkend="glossary-sequence">Sequence</glossterm> will never generate the same number twice, + which makes it useful for generating + <glossterm linkend="glossary-primary-key">Primary Key</glossterm> values. + </para> + <para> + For more information, see + <xref linkend="sql-createsequence"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-shared-memory"> + <glossterm>Shared Memory</glossterm> + <glossdef> + <para> + <acronym>RAM</acronym> which is used by the processes common to an + <glossterm linkend="glossary-instance">Instance</glossterm>. It mirrors parts of + <glossterm linkend="glossary-database">Database</glossterm> files, provides an area for + <glossterm linkend="glossary-wal-record">WAL Record</glossterm>s, and stores additional common + information. Note that <glossterm linkend="glossary-shared-memory">Shared Memory</glossterm> belongs to + the complete <glossterm linkend="glossary-instance">Instance</glossterm>, not to a single + <glossterm linkend="glossary-database">Database</glossterm>. + </para> + <para> + <glossterm linkend="glossary-shared-memory">Shared Memory</glossterm> is organized into pages. If a + page is modified, it is called a dirty page until it is written back + to the file system. + </para> + <para> + For more information, see + <xref linkend="runtime-config-resource-memory"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-sql-object"> + <glossterm>SQL Object</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-table">Table</glossterm>, <glossterm linkend="glossary-view">View</glossterm>, + <glossterm linkend="glossary-materialized-view">Materialized View</glossterm>, + <glossterm linkend="glossary-index">Index</glossterm>, <glossterm linkend="glossary-constraint">Constraint</glossterm>, + <glossterm linkend="glossary-sequence">Sequence</glossterm>, <glossterm linkend="glossary-function">Function</glossterm>, + <glossterm linkend="glossary-procedure">Procedure</glossterm>, <glossterm linkend="glossary-trigger">Trigger</glossterm>, + data type, or operator. Every <glossterm linkend="glossary-sql-object">SQL Object</glossterm> + belongs to exactly one <glossterm linkend="glossary-schema">Schema</glossterm>. + </para> + <para> + For more information, see + <xref linkend="manage-ag-overview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-stats-collector"> + <glossterm>Stats Collector</glossterm> + <glossdef> + <para> + This process collects statistical information about the + <glossterm linkend="glossary-cluster">Cluster</glossterm>'s activities. + </para> + <para> + For more information, see + <xref linkend="monitoring-stats"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-system-catalog"> + <glossterm>System Catalog</glossterm> + <glossdef> + <para> + A collection of <glossterm linkend="glossary-table">Table</glossterm>s and + <glossterm linkend="glossary-view">View</glossterm>s which describe the structure of all + <acronym>SQL</acronym> objects of the <glossterm linkend="glossary-database">Database</glossterm> + and the <glossterm linkend="glossary-global-sql-object">Global SQL Object</glossterm>s of the + <glossterm linkend="glossary-cluster">Cluster</glossterm>. The <glossterm linkend="glossary-system-catalog">System + Catalog</glossterm> resides in the schema + <literal>pg_catalog</literal>. Main parts are mirrored as + <glossterm linkend="glossary-view">View</glossterm>s in the <glossterm linkend="glossary-schema">Schema</glossterm> + <literal>information_schema</literal>. + </para> + <para> + For more information, see + <xref linkend="ddl-schemas"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-table"> + <glossterm>Table</glossterm> + <glossdef> + <para> + A collection of <glossterm linkend="glossary-tuple">Tuple</glossterm>s (also known as + <glossterm linkend="glossary-row">Row</glossterm>s or <glossterm linkend="glossary-record">Record</glossterm>s) having + a common data structure (the same number of + <glossterm linkend="glossary-attribute">Attribute</glossterm>s, in the same order, having the same + name and type per position). A <glossterm linkend="glossary-table">Table</glossterm> is the + most common form of <glossterm linkend="glossary-relation">Relation</glossterm> in + <productname>PostgreSQL</productname>. + </para> + <para> + For more information, see + <xref linkend="sql-createtable"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-tablespace"> + <glossterm>Tablespace</glossterm> + <glossdef> + <para> + A named location on the server filesystem. All <glossterm linkend="glossary-sql-object">SQL Object</glossterm>s + which require storage beyond their definition in the + <glossterm linkend="glossary-system-catalog">System Catalog</glossterm> + must belong to a single tablespace. + </para> + <para> + For more information, see + <xref linkend="manage-ag-tablespaces"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-temporary-table"> + <glossterm>Temporary Table</glossterm> + <glossdef> + <para> + <glossterm linkend="glossary-table">Table</glossterm>s that exist either for the lifetime of a + <glossterm linkend="glossary-session">Session</glossterm> or a + <glossterm linkend="glossary-transaction">Transaction</glossterm>, as specified at the time of creation. The + data in them is not visible to other sessions, + and is not <glossterm linkend="glossary-logged">Logged</glossterm>. + <glossterm linkend="glossary-temporary-table">Temporary Table</glossterm>s are often used to store + intermediate data for a multi-step operation. + </para> + <para> + For more information, see + <xref linkend="sql-createtable"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-transaction"> + <glossterm>Transaction</glossterm> + <glossdef> + <para> + A combination of commands that must act as a single + <glossterm linkend="glossary-atomic">Atomic</glossterm> command: they all succeed or all fail + as a single unit, and their effects are not visible to other + <glossterm linkend="glossary-session">Session</glossterm>s until + the <glossterm linkend="glossary-transaction">Transaction</glossterm> is complete. + </para> + <para> + For more information, see + <xref linkend="transaction-iso"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-trigger"> + <glossterm>Trigger</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-function">Function</glossterm> which can be defined to execute + whenever a certain operation (<command>INSERT</command>, + <command>UPDATE</command>, <command>DELETE</command>, + <command>TRUNCATE</command>) is applied to a <glossterm linkend="glossary-relation">Relation</glossterm>. + A <glossterm linkend="glossary-trigger">Trigger</glossterm> + executes within the same <glossterm linkend="glossary-transaction">Transaction</glossterm> as the + statement which invoked it, and if the <glossterm linkend="glossary-function">Function</glossterm> + fails, then the invoking statement also fails. + </para> + <para> + For more information, see + <xref linkend="sql-createtrigger"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-tuple"> + <glossterm>Tuple</glossterm> + <glossdef> + <para> + A collection of <glossterm linkend="glossary-attribute">Attribute</glossterm>s in a fixed order. + That order may be defined by the <glossterm linkend="glossary-table">Table</glossterm> where + the <glossterm linkend="glossary-tuple">Tuple</glossterm> is found, in which case the + <glossterm linkend="glossary-tuple">Tuple</glossterm> is often called a + <glossterm linkend="glossary-row">Row</glossterm> or <glossterm linkend="glossary-record">Record</glossterm>. It may + also be defined by the structure of a + <glossterm linkend="glossary-result-set">Result Set</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-unique"> + <glossterm>Unique</glossterm> + <glossdef> + <para> + The condition of having no duplicate values in the same + <glossterm linkend="glossary-column">Column</glossterm> of a <glossterm linkend="glossary-relation">Relation</glossterm>. + Often used in the concept of + <glossterm linkend="glossary-unique-index">Unique Index</glossterm>es. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-unlogged"> + <glossterm>Unlogged</glossterm> + <glossdef> + <para> + Changes to an unlogged <glossterm linkend="glossary-relation">Relation</glossterm> are not + reflected in the <glossterm linkend="glossary-wal">WAL Log</glossterm>. This disables + replication and crash recovery for these relations. + </para> + <para> + The primary use of unlogged tables is for storing + transient work data that must be shared across processes. + </para> + <para> + <glossterm linkend="glossary-temporary-table">Temporary Table</glossterm>s are always unlogged. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-update"> + <glossterm>Update</glossterm> + <glossdef> + <para> + A <acronym>SQL</acronym> command used to modify <glossterm linkend="glossary-row">Row</glossterm>s + that may already exist in a specified <glossterm linkend="glossary-table">Table</glossterm>. + It cannot create or remove rows. + </para> + <para> + For more information, see + <xref linkend="sql-update"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-user"> + <glossterm>User</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-role">Role</glossterm> that has the <literal>LOGIN</literal> + privilege is said to be a <glossterm linkend="glossary-user">User</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-user-mapping"> + <glossterm>User Mapping</glossterm> + <glossdef> + <para> + The translation of login credentials in the local + <glossterm linkend="glossary-database">Database</glossterm> to credentials in a remote data system + defined by a <glossterm linkend="glossary-foreign-data-wrapper">Foreign Data Wrapper</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-createusermapping"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-vacuum"> + <glossterm>Vacuum</glossterm> + <glossdef> + <para> + The process of removing outdated <acronym>MVCC</acronym> + <glossterm linkend="glossary-tuple">Tuple</glossterm>s from a <glossterm linkend="glossary-heap">Heap</glossterm> or + <glossterm linkend="glossary-index">Index</glossterm>. This can be initiated through the use of + the <command>VACUUM</command> command, but can also be handled automatically + via <glossterm linkend="glossary-autovacuum">Autovacuum</glossterm> processes. + </para> + <para> + For more information, see + <xref linkend="sql-vacuum"/> . + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-view"> + <glossterm>View</glossterm> + <glossdef> + <para> + A <glossterm linkend="glossary-relation">Relation</glossterm> that is defined by a + <command>SELECT</command> statement, but has no storage of its own. + Any time a query references a <glossterm linkend="glossary-view">View</glossterm>, the + definition of the <glossterm linkend="glossary-view">View</glossterm> is substituted into the + query as if the user had typed that subquery instead of the name of + the <glossterm linkend="glossary-view">View</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-createview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-archiver"> + <glossterm>WAL Archiver (process)</glossterm> + <glossdef> + <para> + A process that saves copies of <glossterm linkend="glossary-wal-file">WAL File</glossterm>s + for the purposes of creating backups or keeping + <glossterm linkend="glossary-replica">Replica</glossterm>s current. + </para> + <para> + For more information, see + <xref linkend="continuous-archiving"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-file"> + <glossterm>WAL File</glossterm> + <glossdef> + <para> + Each of the numerically-numbered files that provide storage space for + <glossterm linkend="glossary-wal">WAL</glossterm>. + The files are all of the same predefined size + and are written in sequential order, interspersing changes + as they occur in multiple simultaneous sessions. + If the system crashes, the files are read in order, and each of the + changes are replayed to restore the system to the state as it was + before the crash. + </para> + <para> + Each WAL file can be released after a + <glossterm linkend="glossary-checkpoint">checkpoint</glossterm> + writes all the changes in it to the corresponding data files. + Releasing the file can be done either by deleting it, or by changing its + name so that it will be used in the future, which is called + <firstterm>recycling</firstterm>. + </para> + + <para> + For more information, see + <xref linkend="wal-internals"/>. + </para> + </glossdef> + </glossentry> + + <glossentry> + <glossterm>WAL</glossterm> + <glosssee otherterm="glossary-wal" /> + </glossentry> + + <glossentry id="glossary-wal-record"> + <glossterm>WAL Record</glossterm> + <glossdef> + <para> + A low-level description of an individual data change. + It contains sufficient information for the data change to be + re-executed (<firstterm>replayed</firstterm>) in case a system failure + causes the change to be lost. + WAL records use a non-printable binary format. + </para> + <para> + For more information, see + <xref linkend="wal-internals"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-segment"> + <glossterm>WAL Segment</glossterm> + <glosssee otherterm="glossary-wal-file" /> + </glossentry> + + <glossentry id="glossary-wal-writer"> + <glossterm linkend="glossary-wal-writer">WAL Writer (process)</glossterm> + <glossdef> + <para> + A process that writes <glossterm linkend="glossary-wal-record">WAL records</glossterm> + from <glossterm id="linkend-shared-memory">shared memory</glossterm> to + <glossterm id="linkend-wal-file">WAL files</glossterm>. + </para> + <para> + For more information, see + <xref linkend="runtime-config-wal"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-window-frame"> + <glossterm>Window frame</glossterm> + <glossdef> + <para> + In a result set, a subset of neighboring rows that match some user + specified criteria form a window frame. + For example, in a query that returns employees across several departments, + the employees from each specific department can form one window frame. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-window-function"> + <glossterm>Window Function</glossterm> + <glossdef> + <para> + A type of <glossterm linkend="glossary-function">function</glossterm> whose + result is based on values found in + <glossterm linkend="glossary-tuple">rows</glossterm> of the same + <glossterm linkend="glossary-window-frame">window frame</glossterm>. + All <glossterm linkend="glossary-aggregate">aggregate functions</glossterm> + can be used as window functions, but window functions can also be + used to, for example, give ranks to each of the rows in the window frame. + Also known as <firstterm>analytic functions</firstterm>. + </para> + <para> + For more information, see + <xref linkend="tutorial-window"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal"> + <glossterm>Write-Ahead Log</glossterm> + <glossdef> + <para> + The journal that keeps track of the changes in the + <glossterm linkend="glossary-instance">Instance</glossterm> as user- and system-invoked + operations take place. It comprises many individual + <glossterm linkend="glossary-wal-record">WAL records</glossterm> written + sequentially to <glossterm linkend="glossary-wal-file">WAL files</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-unique-index"> + <glossterm>Unique Index</glossterm> + <glossdef> + <para> + TODO - we never defined this and we might just use the component glossterms "unique" and "index" + </para> + </glossdef> + </glossentry> + </glosslist> +</appendix> diff --git a/doc/src/sgml/postgres.sgml b/doc/src/sgml/postgres.sgml index 1f7bd32878..ba3d626102 100644 --- a/doc/src/sgml/postgres.sgml +++ b/doc/src/sgml/postgres.sgml @@ -278,6 +278,7 @@ &docguide; &limits; &acronyms; + &glossary; &color; </part> -- 2.20.1
