On Sun, Mar 29, 2020 at 5:29 AM Jürgen Purtz <juer...@purtz.de> wrote:
> On 27.03.20 21:12, Justin Pryzby wrote: > > On Fri, Mar 20, 2020 at 11:32:25PM +0100, Jürgen Purtz wrote: > >>>> + <glossterm>Archiver</glossterm> > >>> Can you change that to archiver process ? > >> I prefer the short term without the addition of 'process' - concerning > >> 'Archiver' as well as the other cases. But I'm not an native English > >> speaker. > > I didn't like it due to lack of context. > > > > What about "wal archiver" ? > > > > It occured to me when I read this. > > > https://www.postgresql.org/message-id/20200327.163007.128069746774242774.horikyota.ntt%40gmail.com > > > "WAL archiver" is ok for me. In the current documentation we have 2 > places with "WAL archiver" and 4 with "archiver"-only > (high-availability.sgml, monitoring.sgml). > > "backend process" is an exception to the other terms because the > standalone term "backend" is sensibly used in diverse situations. > > Kind regards, Jürgen > I've taken Alvarao's fixes and done my best to incorporate the feedback into a new patch, which Roger's (tech writer) reviewed yesterday. The changes are too numerous to list, but the highlights are: New definitions: * All four ACID terms * Vacuum (split off from Autovacuum) * Tablespace * WAL Archiver (replaces Archiver) Changes to existing terms: * Implemented most wording changes recommended by Justin * all remaining links were either made into xrefs or edited out of existence * de-tagged most second uses of of a term within a definition Did not do * Addressed the " Process" suffix suggested by Justin. There isn't consensus on these changes, and I'm neutral on the matter * change the Cast definition. I think it's important to express that a cast has a FROM datatype as well as a TO * anything host/server related as I couldn't see a consensus reached Other thoughts: * Trivial definitions that are just see-other-definition are ok with me, as the goal of this glossary is to aid in discovery of term meanings, so knowing that two terms are interchangable is itself helpful It is my hope that this revision represents the final _structural_ change to the glossary. New definitions and edits to existing definitions will, of course, go on forever.
From 8a163603102f51a3eddfb05c51baf3b840c5d7f7 Mon Sep 17 00:00:00 2001 From: coreyhuinker <corey.huin...@gmail.com> Date: Mon, 30 Mar 2020 13:08:27 -0400 Subject: [PATCH] glossary v4 --- doc/src/sgml/filelist.sgml | 1 + doc/src/sgml/glossary.sgml | 1551 ++++++++++++++++++++++++++++++++++++ doc/src/sgml/postgres.sgml | 1 + 3 files changed, 1553 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..eab14f3c9b --- /dev/null +++ b/doc/src/sgml/glossary.sgml @@ -0,0 +1,1551 @@ +<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-aggregating"> + <glossterm>Aggregating</glossterm> + <glossdef> + <para> + The act of combining a collection of data (input) values into + a single output value, which may not be of the same type as the + input values. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-aggregate"> + <glossterm>Aggregate Function</glossterm> + <glossdef> + <para> + A <glossterm>Function</glossterm> that combines multiple input values, + for example by counting, averaging or adding them all together, + yielding a single output value. + </para> + <para> + For more information, see + <xref linkend="functions-aggregate"/>. + </para> + <para> + See also <glossterm>Window Function</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-analytic"> + <glossterm>Analytic</glossterm> + <glossdef> + <para> + A <glossterm>Function</glossterm> whose computed value can reference + values found in nearby <glossterm>Row</glossterm>s of the same + <glossterm>Result Set</glossterm>. + </para> + <para> + For more information, see + <xref linkend="tutorial-window"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-atomic"> + <glossterm>Atomic</glossterm> + <glossdef> + <para> + In reference to the value of an <glossterm>Attribute</glossterm> or + <glossterm>Datum</glossterm>: an item that cannot be broken down + into smaller components. + </para> + <para> + In reference to an operation: an event that cannot be completed in + part; it must either entirely succeed or entirely fail. For + example, a series of <acronym>SQL</acronym> statements can be + combined into a <glossterm>Transaction</glossterm>, and that + transaction is said to be atomic. + <glossterm>Atomic</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-atomicity"> + <glossterm>Atomicity</glossterm> + <glossdef> + <para> + One of the <acronym>ACID</acronym> properties. This is the state of + being <glossterm>Atomic</glossterm> in the operational/transactional sense. + </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>Tuple</glossterm> or <glossterm>Table</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-autovacuum"> + <glossterm>Autovacuum</glossterm> + <glossdef> + <para> + <glossterm>Background Worker</glossterm> processes that routinely + perform <glossterm>Vacuum</glossterm> operations. + </para> + <para> + For more information, see + <xref linkend="routine-vacuuming"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-backend-process"> + <glossterm>Backend Process</glossterm> + <glossdef> + <para> + Processes of an <glossterm>Instance</glossterm> which act on behalf of + client <glossterm>Connection</glossterm>s and handle their requests. + </para> + <para> + (Don't confuse this term with the similar terms <glossterm>Background + Worker</glossterm> or <glossterm>Background Writer</glossterm>). + </para> + </glossdef> + </glossentry> + +<!-- + <glossentry id="glossary-backend-server"> + <glossterm>Backend Server</glossterm> + <glossdef> + <para> + See <glossterm>Instance</glossterm>. + </para> + </glossdef> + </glossentry> +--> + + <glossentry id="glossary-background-worker"> + <glossterm>Background Worker</glossterm> + <glossdef> + <para> + Individual processes within an <glossterm>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</glossterm> + <glossdef> + <para> + A process that continuously writes dirty pages from + <glossterm>Shared Memory</glossterm> to the file system. + It wakes up periodically, but + works only for a short period in order to distribute 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>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>Database</glossterm> in + <productname>PostgreSQL</productname>'s terminology. + </para> + <para> + This should not be confused with the + <glossterm>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>Constraint</glossterm> defined on a + <glossterm>Relation</glossterm> which restricts the values allowed in + one or more <glossterm>Attribute</glossterm>s. The <glossterm>Check + Constraint</glossterm> can make reference to any + attribute in the + <glossterm>Relation</glossterm>, but cannot reference other + <glossterm>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</glossterm> + <glossdef> + <para> + A process that writes dirty pages and <glossterm>WAL + Record</glossterm>s to the file system and creates a special + checkpoint 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 have been collected. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-checkpoint"> + <glossterm>Checkpoint</glossterm> + <glossdef> + <para> + A point in time when all older dirty pages of the + <glossterm>Shared Memory</glossterm>, all older <glossterm>WAL Record</glossterm>s, + and a special <glossterm>Checkpoint record</glossterm> have been written + and flushed to disk. + </para> + <para> + For more information, see + <xref linkend="sql-checkpoint"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-cluster"> + <glossterm>Cluster</glossterm> + <glossdef> + <para> + A group of <glossterm>Database</glossterm>s plus their + <glossterm>Global SQL Object</glossterm>s. The + <glossterm>Cluster</glossterm> is managed by exactly one + <glossterm>Instance</glossterm>. A newly created + <glossterm>Cluster</glossterm> will have three + <glossterm>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>Database</glossterm>s aside + from these three. + </para> + <para> + Don't confuse the <productname>PostgreSQL</productname>-specific term + <glossterm>Cluster</glossterm> with the SQL command + <literal>CLUSTER</literal>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-column"> + <glossterm>Column</glossterm> + <glossdef> + <para> + An <glossterm>Attribute</glossterm> found in a + <glossterm>Table</glossterm> or <glossterm>View</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-commit"> + <glossterm>Commit</glossterm> + <glossdef> + <para> + The act of finalizing a <glossterm>Transaction</glossterm> within the + <glossterm>Database</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>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 server process. If the two involved processes reside on the + same <glossterm>Server</glossterm>, then the connection can either use + <acronym>TCP/IP</acronym> or Unix-domain sockets. Otherwise, + only <acronym>TCP/IP</acronym> can be used. + </para> + <para> + For more information, see + <xref linkend="runtime-config-connection"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-consistency"> + <glossterm>Consistency</glossterm> + <glossdef> + <para> + One of the <acronym>ACID</acronym> properties. This means that the database + is always in compliance with its own rules such as <glossterm>Table</glossterm> + structure, <glossterm>Constraint</glossterm>s, + <glossterm>Uniqueness</glossterm>, etc. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-constraint"> + <glossterm>Constraint</glossterm> + <glossdef> + <para> + A restriction on the values of data allowed within a + <glossterm>Table</glossterm>. + </para> + <para> + For more information, see + <xref linkend="ddl-constraints"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-data-area"> + <glossterm>Data Area</glossterm> + <glossdef> + <para> + See <glossterm>Data Directory</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-data-directory"> + <glossterm>Data Directory</glossterm> + <glossdef> + <para> + The base directory on the filesystem of a + <glossterm>Server</glossterm> that contains all data files and + subdirectories associated with a <glossterm>Cluster</glossterm> with + the exception of <glossterm>Tablespace</glossterm>s. The environment + variable <literal>PGDATA</literal> often — but not always — + refers to the <glossterm>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>SQL Object</glossterm>s. + </para> + <para> + For more information, see + <xref linkend="manage-ag-overview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-database-server"> + <glossterm>Database Server</glossterm> + <glossdef> + <para> + See <glossterm>Instance</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-datum"> + <glossterm>Datum</glossterm> + <glossdef> + <para> + The internal representation 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>Row</glossterm>s from a given <glossterm>Table</glossterm> + or <glossterm>Relation</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-delete"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-durability"> + <glossterm>Durability</glossterm> + <glossdef> + <para> + One of the <acronym>ACID</acronym> properties. This is the assurance that once a + <glossterm>Transaction</glossterm> has been <glossterm>Committed</glossterm>, the + data will remain even after a system failure or crash. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-file-segment"> + <glossterm>File Segment</glossterm> + <glossdef> + <para> + A physical file which stores data for a given + <glossterm>Heap</glossterm> or <glossterm>Index</glossterm> object. + <glossterm>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>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>Database</glossterm> so that it appears as if were in local + <glossterm>Table</glossterm>(s). With a Foreign Data Wrapper it is + possible to define a <glossterm>Foreign Server</glossterm> and + <glossterm>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>Constraint</glossterm> defined on one or more + <glossterm>Column</glossterm>s in a <glossterm>Table</glossterm> which + requires the value(s) in those <glossterm>Column</glossterm>s to + identify exactly one <glossterm>Row</glossterm> in the specified + <glossterm>Table</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-foreign-server"> + <glossterm>Foreign Server</glossterm> + <glossdef> + <para> + A named collection of <glossterm>Foreign Table</glossterm>s which all + use the same <glossterm>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>Relation</glossterm> which appears to have + <glossterm>Row</glossterm>s and <glossterm>Column</glossterm>s similar + to a regular <glossterm>Table</glossterm>, but will forward requests + for data through its <glossterm>Foreign Data Wrapper</glossterm>, + which will return <glossterm>Result Set</glossterm>s structured + according to the definition of the <glossterm>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 + <glossterm>Function</glossterm>s 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>SQL Object</glossterm>s which do not belong to a specific + <glossterm>Schema</glossterm>. + </para> + <para> + Objects that exist at the <glossterm>Database</glossterm> level + include Extensions such as + <glossterm>Foreign Data Wrapper</glossterm>s. + </para> + <para> + Objects that exist at the <glossterm>Cluster</glossterm> level + include <glossterm>Role</glossterm>s, + <glossterm>Tablespace</glossterm>s, + <glossterm>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>User</glossterm>s or <glossterm>Role</glossterm>s to access + specific objects within the <glossterm>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>Row</glossterm> attributes + (i.e. the data). The <glossterm>Heap</glossterm> is realized within + <glossterm>Database</glossterm> files. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-host"> + <glossterm>Host</glossterm> + <glossdef> + <para> + See <glossterm>Server</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-index"> + <glossterm>Index</glossterm> + <glossdef> + <para> + A <glossterm>Relation</glossterm> that contains data derived from a + <glossterm>Table</glossterm> (or <glossterm>Relation</glossterm> types + such as a <glossterm>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>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>Instance</glossterm> is a group of processes plus their + common <glossterm>Shared Memory</glossterm> running on a single + <glossterm>Server</glossterm>. The <glossterm>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>Connection</glossterm>s to client programs, backup, + recovery, replication, privileges, etc. + </para> + <para> + An <glossterm>Instance</glossterm> manages exactly one + <glossterm>Cluster</glossterm>. + </para> + <para> + Many <glossterm>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> + One of the <acronym>ACID</acronym> properties. This means that concurrently running + <glossterm>Transaction</glossterm>s affect the database exactly as if they had been + executed sequentially. + </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>Relation</glossterm>s. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-key"> + <glossterm>Key</glossterm> + <glossdef> + <para> + A means of identifying a <glossterm>Row</glossterm> within a + <glossterm>Table</glossterm> or <glossterm>Relation</glossterm> by + values contained within one or more <glossterm>Attribute</glossterm>s + in that <glossterm>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-log-writer"> + <glossterm>Log Writer</glossterm> + <glossdef> + <para> + If activated and parameterized, the + <glossterm>Log Writer</glossterm> process + writes information about database events into the current + <glossterm>Log File</glossterm>. When reaching certain time- or + volume-dependent criteria, a new log file is created. + </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>WAL Record</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-logged"> + <glossterm>Logged</glossterm> + <glossdef> + <para> + A <glossterm>Table</glossterm> is considered + <glossterm>Logged</glossterm> if changes to it are sent to the + <glossterm>WAL Log</glossterm>. By default, all regular + <glossterm>Table</glossterm>s are <glossterm>Logged</glossterm>. A + table can be specified as <glossterm>Unlogged</glossterm> either at + creation time or via the <command>ALTER TABLE</command> command. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-master"> + <glossterm>Master</glossterm> + <glossdef> + <para> + When two or more <glossterm>Database</glossterm>s are linked via + <glossterm>Replication</glossterm>, the <glossterm>Server</glossterm> + that is considered the authoritative source of information is called + the <glossterm>Master</glossterm>. + </para> + </glossdef> + </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>Materialized + View</glossterm>s, meaning that the data derived from the + <glossterm>View</glossterm> is actually stored on disk separately from + the sources of that data. When using the term + <glossterm>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>Relation</glossterm> that is defined in the same way that + a <glossterm>View</glossterm> is, but stores data in the same way + that a <glossterm>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 id="glossary-partition"> + <glossterm>Partition</glossterm> + <glossdef> + <para> + A <glossterm>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> + When referring to an <glossterm>Analytic</glossterm> + <glossterm>Function</glossterm>: a partition is a definition + that identifies which neighboring + <glossterm>Row</glossterm>s can be considered by the + function. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-postmaster"> + <glossterm>Postmaster</glossterm> + <glossdef> + <para> + The very first process of an <glossterm>Instance</glossterm>. It + starts the other processes and creates + <glossterm>Backend Process</glossterm>es on demand. + </para> + <para> + For more information, see + <xref linkend="server-start"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-primary-key"> + <glossterm>Primary Key</glossterm> + <glossdef> + <para> + A special case of a <glossterm>Unique Index</glossterm> defined on a + <glossterm>Table</glossterm> or other <glossterm>Relation</glossterm> + that also guarantees that all of the <glossterm>Attribute</glossterm>s + within the <glossterm>Primary Key</glossterm> do not have + <glossterm>Null</glossterm> values. As the name implies, there can be + only one <glossterm>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>Database</glossterm>. A <glossterm>Procedure</glossterm> can + be written in a variety of programming languages. They may seem + similar to <glossterm>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-record"> + <glossterm>Record</glossterm> + <glossdef> + <para> + See <glossterm>Tuple</glossterm>. + </para> + <para> + A single <glossterm>Row</glossterm> of a <glossterm>Table</glossterm> + or other <glossterm>Relation</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-referential-integrity"> + <glossterm>Referential Integrity</glossterm> + <glossdef> + <para> + A means of restricting data in one <glossterm>Relation</glossterm> + so that it must have matching data in another + <glossterm>Relation</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-relation"> + <glossterm>Relation</glossterm> + <glossdef> + <para> + The generic term for all objects in a <glossterm>Database</glossterm> + that have a name and a list of <glossterm>Attribute</glossterm>s + defined in a specific order. <glossterm>Table</glossterm>s, + <glossterm>View</glossterm>s, <glossterm>Foreign Table</glossterm>s, + <glossterm>Materialized View</glossterm>s, and + <glossterm>Index</glossterm>es are all + <glossterm>Relation</glossterm>s. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-replica"> + <glossterm>Replica</glossterm> + <glossdef> + <para> + A <glossterm>Database</glossterm> that is paired with a + <glossterm>Master</glossterm> + database and is maintaining a copy of some or + all of the Master <glossterm>Database</glossterm>'s data. The primary + 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>Master</glossterm> becomes unavailable. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-replication"> + <glossterm>Replication</glossterm> + <glossdef> + <para> + The act of reproducing data on one <glossterm>Server</glossterm> onto + another server called a <glossterm>Replica</glossterm>. This can take the + form of Physical <glossterm>Replication</glossterm>, where all file + changes from one server are copied verbatim, + or Logical <glossterm>Replication</glossterm> where a defined subset + of data changes are conveyed. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-result-set"> + <glossterm>Result Set</glossterm> + <glossdef> + <para> + A data structure transmitted from a <glossterm>Server</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>Row</glossterm>s with the same ordered set of + <glossterm>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>Database</glossterm> objects for a named list of + <glossterm>User</glossterm>s and <glossterm>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>Database</glossterm>. <glossterm>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>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>Transaction</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-rollback"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-row"> + <glossterm>Row</glossterm> + <glossdef> + <para> + See <glossterm>Tuple</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-savepoint"> + <glossterm>Savepoint</glossterm> + <glossdef> + <para> + A special mark inside the sequence of steps in a + <glossterm>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>Schema</glossterm> is a namespace for + <glossterm>SQL object</glossterm>s, which all reside in the same + <glossterm>database</glossterm>. Each <glossterm>SQL + object</glossterm> must reside in exactly one + <glossterm>Schema</glossterm>. + </para> + <para> + In general, the names of <glossterm>SQL Object</glossterm>s in the + schema are unique — even across different types of objects. The lone + exception is the case of <glossterm>Unique</glossterm> + <glossterm>Constraint</glossterm>s, in which case there + <emphasis>must</emphasis> be a <glossterm>Unique Index</glossterm> + with the same name and <glossterm>Schema</glossterm> as the + <glossterm>Constraint</glossterm>. There is no restriction on reusing + a name in multiple <glossterm>Schema</glossterm>s. + </para> + <para> + Many <glossterm>SQL Object</glossterm>s reside in the default + <glossterm>Schema</glossterm> <literal>public</literal>, but it is + expected that more schemas are created to hold application-specific + <glossterm>SQL Object</glossterm>s. + </para> + <para> + More generically, the term <glossterm>Schema</glossterm> is used to + mean all data descriptions (<glossterm>Table</glossterm> definitions, + <glossterm>Constraint</glossterm>s, comments) for a given + <glossterm>Database</glossterm>. + </para> + <para> + For more information, see + <xref linkend="ddl-schemas"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-segment"> + <glossterm>Segment</glossterm> + <glossdef> + <para> + See <glossterm>File Segment</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-select"> + <glossterm>Select</glossterm> + <glossdef> + <para> + The command used to query a <glossterm>Database</glossterm>. Normally, + <command>SELECT</command>s are not expected to modify the + <glossterm>Database</glossterm> in any way, but it is possible that + <glossterm>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>Database</glossterm> + appears to be frozen for the duration of the + <glossterm>Transaction</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-server"> + <glossterm>Server</glossterm> + <glossdef> + <para> + The term <glossterm>Server</glossterm> denotes real hardware, a + container, or a Virtual Machine. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-session"> + <glossterm>Session</glossterm> + <glossdef> + <para> + A <glossterm>Connection</glossterm> to the <glossterm>Database</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-sequence"> + <glossterm>Sequence</glossterm> + <glossdef> + <para> + A <glossterm>Database</glossterm> object which represents the + mathematical concept of a numerical integral sequence. It can be + thought of as a <glossterm>Table</glossterm> with exactly one + <glossterm>Row</glossterm> and one <glossterm>Column</glossterm>. The + value stored is known as the current value. A + <glossterm>Sequence</glossterm> has a defined direction (usually + increasing) and an interval step (usually 1). Whenever the + <literal>NEXTVAL</literal> pseudo-column of a + <glossterm>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>Sequence</glossterm> are never reverted, even in the case of + a <glossterm>Rollback</glossterm>, which means that the + <glossterm>Sequence</glossterm> will never generate the same number twice, + which makes it useful for generating + <glossterm>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>Instance</glossterm>. It mirrors parts of + <glossterm>Database</glossterm> files, provides an area for + <glossterm>WAL Record</glossterm>s, and stores additional common + information. Note that <glossterm>Shared Memory</glossterm> belongs to + the complete <glossterm>Instance</glossterm>, not to a single + <glossterm>Database</glossterm>. + </para> + <para> + <glossterm>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>Table</glossterm>, <glossterm>View</glossterm>, + <glossterm>Materialized View</glossterm>, + <glossterm>Index</glossterm>, <glossterm>Constraint</glossterm>, + <glossterm>Sequence</glossterm>, <glossterm>Function</glossterm>, + <glossterm>Procedure</glossterm>, <glossterm>Trigger</glossterm>, + data type, or operator. Every <glossterm>SQL Object</glossterm> + belongs to exactly one <glossterm>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>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>Table</glossterm>s and + <glossterm>View</glossterm>s which describe the structure of all + <acronym>SQL</acronym> objects of the <glossterm>Database</glossterm> + and the <glossterm>Global SQL Object</glossterm>s of the + <glossterm>Cluster</glossterm>. The <glossterm>System + Catalog</glossterm> resides in the schema + <literal>pg_catalog</literal>. Main parts are mirrored as + <glossterm>View</glossterm>s in the <glossterm>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>Tuple</glossterm>s (also known as + <glossterm>Row</glossterm>s or <glossterm>Record</glossterm>s) having + a common data structure (the same number of + <glossterm>Attribute</glossterm>s, in the same order, having the same + name and type per position). A <glossterm>Table</glossterm> is the + most common form of <glossterm>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>SQL Object</glossterm>s + which require storage beyond their definition in the + <glossterm>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-tables"> + <glossterm>Temporary Table</glossterm> + <glossdef> + <para> + <glossterm>Table</glossterm>s that exist either for the lifetime of a + <glossterm>Session</glossterm> or a + <glossterm>Transaction</glossterm>, as specified at the time of creation. The + data in them is not visible to other sessions, + and is not <glossterm>Logged</glossterm>. + <glossterm>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>Atomic</glossterm> command: they all succeed or all fail + as a single unit, and their effects are not visible to other + <glossterm>Session</glossterm>s until + the <glossterm>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>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>Relation</glossterm>. + A <glossterm>Trigger</glossterm> + executes within the same <glossterm>Transaction</glossterm> as the + statement which invoked it, and if the <glossterm>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>Attribute</glossterm>s in a fixed order. + That order may be defined by the <glossterm>Table</glossterm> where + the <glossterm>Tuple</glossterm> is found, in which case the + <glossterm>Tuple</glossterm> is often called a + <glossterm>Row</glossterm> or <glossterm>Record</glossterm>. It may + also be defined by the structure of a + <glossterm>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>Relation</glossterm>. Often used in the concept of + <glossterm>Unique Index</glossterm>es. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-unlogged"> + <glossterm>Unlogged</glossterm> + <glossdef> + <para> + Changes to an unlogged <glossterm>Relation</glossterm> are not + reflected in the <glossterm>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>Temporary Table</glossterm>s are always unlogged. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-update"> + <glossterm>Update</glossterm> + <glossdef> + <para> + A command used to modify <glossterm>Row</glossterm>s that may already + exist in a specified <glossterm>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>Role</glossterm> that has the <literal>LOGIN</literal> + privilege is said to be a <glossterm>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>Database</glossterm> to credentials in a remote data system + defined by a <glossterm>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>Tuple</glossterm>s from a <glossterm>Heap</glossterm> or + <glossterm>Index</glossterm>. This can be initiated through the use of + the <command>VACUUM</command> command, but can also be handled automatically + via <glossterm>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>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>View</glossterm>, the + definition of the <glossterm>View</glossterm> is substituted into the + query as if the user had typed that subquery instead of the name of + the <glossterm>View</glossterm>. + </para> + <para> + For more information, see + <xref linkend="sql-createview"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-archiver"> + <glossterm>WAL Archiver</glossterm> + <glossdef> + <para> + A process that saves copies of <glossterm>WAL File</glossterm>s, + for the purposes of creating backups or keeping + <glossterm>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> + <glossterm>WAL Record</glossterm>s are continously written to the end + of the current <glossterm>WAL File</glossterm>. WAL files + as well as WAL records belong + to the complete <glossterm>Cluster</glossterm>, not to a single + <glossterm>Database</glossterm>. After a WAL file + is full, a new WAL file is + created, or, under certain conditions, one of the previous + <glossterm>WAL File</glossterm>s is renamed and reused. + </para> + <para> + The sequence of <glossterm>WAL Record</glossterm>s + represents the sequence of changes that have taken place in the + <glossterm>Cluster</glossterm>. + </para> + <para> + For more information, see + <xref linkend="wal-internals"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-log"> + <glossterm>WAL Log</glossterm> + <glossdef> + <para> + See <glossterm>WAL File</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-record"> + <glossterm>WAL Record</glossterm> + <glossdef> + <para> + A <glossterm>WAL Record</glossterm> contains either new or changed + <glossterm>Heap</glossterm> or <glossterm>Index</glossterm> data or + information about a <command>COMMIT</command>, + <command>ROLLBACK</command>, <command>SAVEPOINT</command>, or + <glossterm>Checkpointer</glossterm> operation. 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> + <glossdef> + <para> + See <glossterm>WAL File</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-segment-file"> + <glossterm>WAL Segment File</glossterm> + <glossdef> + <para> + See <glossterm>WAL File</glossterm>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-wal-writer"> + <glossterm>WAL Writer</glossterm> + <glossdef> + <para> + This process writes <glossterm>WAL Record</glossterm>s from + <glossterm>Shared Memory</glossterm> to + <glossterm>WAL File</glossterm>s. + </para> + <para> + For more information, see + <xref linkend="runtime-config-wal"/>. + </para> + </glossdef> + </glossentry> + + <glossentry id="glossary-window-function"> + <glossterm>Window Function</glossterm> + <glossdef> + <para> + A type of <glossterm>Function</glossterm> similar to an + <glossterm>Aggregate</glossterm> in that it can derive its value from a + set of <glossterm>Row</glossterm>s in a <glossterm>Result + Set</glossterm>, while retaining the original source data. + </para> + <para> + For more information, see + <xref linkend="tutorial-window"/>. + </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
