</glossentry>
<glossentry id="glossary-aggregate">
- <glossterm>Aggregate function</glossterm>
+ <glossterm>Aggregate function (routine)</glossterm>
<glossdef>
<para>
A <glossterm linkend="glossary-function">function</glossterm> that
</glossdef>
</glossentry>
+ <glossentry>
+ <glossterm>Analytic function</glossterm>
+ <glosssee otherterm="glossary-window-function" />
+ </glossentry>
+
<glossentry id="glossary-analyze">
<glossterm>Analyze (operation)</glossterm>
<glossdef>
(Don't confuse this term with the <literal>ANALYZE</literal> option
to the <xref linkend="sql-explain"/> command.)
</para>
+ <para>
+ For more information, see
+ <xref linkend="sql-analyze"/>.
+ </para>
</glossdef>
</glossentry>
- <glossentry>
- <glossterm>Analytic function</glossterm>
- <glosssee otherterm="glossary-window-function" />
- </glossentry>
-
<glossentry id="glossary-atomic">
<glossterm>Atomic</glossterm>
<glossdef>
<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>.
+ <glossterm linkend="glossary-tuple">tuple</glossterm>.
</para>
</glossdef>
</glossentry>
<glosssee otherterm="glossary-data-directory" />
</glossentry>
- <glossentry id="glossary-data-directory">
- <glossterm>Data directory</glossterm>
+ <glossentry id="glossary-database">
+ <glossterm>Database</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 an
- <glossterm linkend="glossary-instance">instance</glossterm> (with the
- exception of <glossterm linkend="glossary-tablespace">tablespaces</glossterm>).
- The environment variable <literal>PGDATA</literal> is commonly used to
- refer to the
- <glossterm linkend="glossary-data-directory">data directory</glossterm>.
- </para>
- <para>
- An <glossterm linkend="glossary-instance">instance</glossterm>'s storage
- space comprises the data directory plus any additional tablespaces.
+ A named collection of
+ <glossterm linkend="glossary-sql-object">local SQL objects</glossterm>.
</para>
<para>
For more information, see
- <xref linkend="storage-file-layout"/>.
+ <xref linkend="manage-ag-overview"/>.
</para>
</glossdef>
</glossentry>
- <glossentry id="glossary-database">
- <glossterm>Database</glossterm>
+ <glossentry id="glossary-db-cluster">
+ <glossterm>Database cluster</glossterm>
<glossdef>
<para>
- A named collection of
- <glossterm linkend="glossary-sql-object">SQL objects</glossterm>.
+ A collection of databases and global SQL objects,
+ and their common static and dynamic metadata.
+ Sometimes referred to as a
+ <firstterm>cluster</firstterm>.
</para>
<para>
- For more information, see
- <xref linkend="manage-ag-overview"/>.
+ In <productname>PostgreSQL</productname>, the term
+ <firstterm>cluster</firstterm> is also sometimes used to refer to an instance.
+ (Don't confuse this term with the SQL command <command>CLUSTER</command>.)
</para>
</glossdef>
</glossentry>
<glosssee otherterm="glossary-instance" />
</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-db-cluster">database cluster</glossterm>
+ (with the exception of
+ <glossterm linkend="glossary-tablespace">tablespaces</glossterm>,
+ and optionally <glossterm linkend="glossary-wal">WAL</glossterm>).
+ The environment variable <literal>PGDATA</literal> is commonly used to
+ refer to the data directory.
+ </para>
+ <para>
+ A <glossterm linkend="glossary-db-cluster">cluster</glossterm>'s storage
+ space comprises the data directory plus any additional tablespaces.
+ </para>
+ <para>
+ For more information, see
+ <xref linkend="storage-file-layout"/>.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry id="glossary-data-page">
<glossterm>Data page</glossterm>
<glossdef>
</glossentry>
<glossentry id="glossary-foreign-table">
- <glossterm>Foreign table</glossterm>
+ <glossterm>Foreign table (relation)</glossterm>
<glossdef>
<para>
A <glossterm linkend="glossary-relation">relation</glossterm> which appears to have
</glossentry>
<glossentry id="glossary-function">
- <glossterm>Function</glossterm>
+ <glossterm>Function (routine)</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.
+ A type of routine that receives zero or more arguments, returns zero or more
+ output values, and is constrained to run within one transaction.
+ Functions are invoked as part of a query, for example via
+ <command>SELECT</command>.
+ Certain functions can return
+ <glossterm linkend="glossary-result-set">sets</glossterm>; those are
+ called <firstterm>set-returning functions</firstterm>.
+ </para>
+ <para>
+ Functions can also be used for
+ <glossterm linkend="glossary-trigger">triggers</glossterm> to invoke.
</para>
<para>
For more information, see
</glossentry>
<glossentry id="glossary-index">
- <glossterm>Index</glossterm>
+ <glossterm>Index (relation)</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>).
+ or <glossterm linkend="glossary-materialized-view">materialized view</glossterm>.
Its internal structure supports fast retrieval of and access to the original
data.
</para>
<glossterm>Instance</glossterm>
<glossdef>
<para>
- A set of databases and accompanying global SQL objects that are stored in
- the same <glossterm linkend="glossary-data-directory">data directory</glossterm>
- in a single <glossterm linkend="glossary-server">server</glossterm>.
- If running, one
+ A group of backend and auxiliary processes that communicate using
+ a common shared memory area. One
<glossterm linkend="glossary-postmaster">postmaster process</glossterm>
- manages a group of backend and auxiliary processes that communicate
- using a common <glossterm linkend="glossary-shared-memory">shared memory</glossterm>
- area. Many instances can run on the same
+ manages the instance; one instance manages exactly one
+ <glossterm linkend="glossary-db-cluster">database cluster</glossterm>
+ with all its databases. Many instances can run on the same
<glossterm linkend="glossary-server">server</glossterm>
as long as their <acronym>TCP</acronym> ports do not conflict.
</para>
The instance handles all key features of a <acronym>DBMS</acronym>:
read and write access to files and shared memory,
assurance of the <acronym>ACID</acronym> properties,
- <glossterm linkend="glossary-connection">connections</glossterm> to client processes,
+ <glossterm linkend="glossary-connection">connections</glossterm> to
+ <glossterm linkend="glossary-client">client processes</glossterm>,
privilege verification, crash recovery, replication, etc.
</para>
- <para>
- In <productname>PostgreSQL</productname>, the term
- <firstterm>cluster</firstterm> is also sometimes used to refer to an instance.
- (Don't confuse this term with the SQL command <command>CLUSTER</command>.)
- </para>
</glossdef>
</glossentry>
<glossterm>Join</glossterm>
<glossdef>
<para>
- An <acronym>SQL</acronym> keyword used in <command>SELECT</command> statements for
- combining data from multiple <glossterm linkend="glossary-relation">relations</glossterm>.
+ An operation and <acronym>SQL</acronym> keyword used in
+ <glossterm linkend="glossary-query">queries</glossterm>
+ for combining data from multiple
+ <glossterm linkend="glossary-relation">relations</glossterm>.
</para>
</glossdef>
</glossentry>
<para>
A means of identifying a <glossterm linkend="glossary-tuple">row</glossterm> within a
<glossterm linkend="glossary-table">table</glossterm> or
- <glossterm linkend="glossary-relation">relation</glossterm> by
+ other <glossterm linkend="glossary-relation">relation</glossterm> by
values contained within one or more
<glossterm linkend="glossary-attribute">attributes</glossterm>
- in that table.
+ in that relation.
</para>
</glossdef>
</glossentry>
</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>
</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>
<glossterm>Master (server)</glossterm>
<glosssee otherterm="glossary-primary-server" />
</glossentry>
<glossentry id="glossary-materialized-view">
- <glossterm>Materialized view</glossterm>
+ <glossterm>Materialized view (relation)</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
+ defined by a <command>SELECT</command> statement
+ (just like a <glossterm linkend="glossary-view">view</glossterm>),
+ 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>
One of several disjoint (not overlapping) subsets of a larger set.
</para>
+ </glossdef>
+ <glossdef>
<para>
In reference to a
<glossterm linkend="glossary-partitioned-table">partitioned table</glossterm>:
</glossdef>
<glossdef>
<para>
- In reference to a <glossterm linkend="glossary-window-function">window function</glossterm>:
+ In reference to a <glossterm linkend="glossary-window-function">window function</glossterm>
+ in a <glossterm linkend="glossary-query">query</glossterm>,
a partition is a user-defined criterion that identifies which neighboring
- <glossterm linkend="glossary-tuple">rows</glossterm> can be considered by the
- function.
+ <glossterm linkend="glossary-tuple">rows</glossterm>
+ of the <glossterm linkend="glossary-result-set">query's result set</glossterm>
+ can be considered by the function.
</para>
</glossdef>
</glossentry>
<glossentry id="glossary-partitioned-table">
- <glossterm>Partitioned table</glossterm>
+ <glossterm>Partitioned table (relation)</glossterm>
<glossdef>
<para>
A <glossterm linkend="glossary-relation">relation</glossterm> that is
</glossdef>
</glossentry>
- <glossentry id="glossary-primary-server">
- <glossterm>Primary (server)</glossterm>
- <glossdef>
- <para>
- When two or more <glossterm linkend="glossary-database">databases</glossterm>
- 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>
</glossdef>
</glossentry>
+ <glossentry id="glossary-primary-server">
+ <glossterm>Primary (server)</glossterm>
+ <glossdef>
+ <para>
+ When two or more <glossterm linkend="glossary-database">databases</glossterm>
+ 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-procedure">
- <glossterm>Procedure</glossterm>
+ <glossterm>Procedure (routine)</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 are
- similar to <glossterm linkend="glossary-function">functions</glossterm>,
- 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
+ A type of routine.
+ Their distinctive qualities are that they do not return values,
+ and that they are allowed to make transactional statements such
as <command>COMMIT</command> and <command>ROLLBACK</command>.
+ They are invoked via the <command>CALL</command> command.
</para>
<para>
For more information, see
<glossterm linkend="glossary-index">indexes</glossterm> are all relations.
</para>
<para>
+ More generically, a relation is a set of tuples; for example,
+ the result of a query is also a relation.
+ </para>
+ <para>
+ In <productname>PostgreSQL</productname>,
<firstterm>Class</firstterm> is an archaic synonym for
<firstterm>relation</firstterm>.
</para>
<glossterm>Result set</glossterm>
<glossdef>
<para>
- A data structure transmitted from a
- <glossterm linkend="glossary-backend">backend process</glossterm> to
- a <glossterm linkend="glossary-client">client</glossterm> upon the
- completion of an <acronym>SQL</acronym>
- command, usually a <command>SELECT</command> but it can be an
+ A <glossterm linkend="glossary-relation">relation</glossterm> transmitted
+ from a <glossterm linkend="glossary-backend">backend process</glossterm>
+ to a <glossterm linkend="glossary-client">client</glossterm> upon the
+ completion of an <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-tuple">rows</glossterm> with the same ordered set of
- <glossterm linkend="glossary-attribute">attributes</glossterm>.
+ clause is specified.
+ </para>
+ <para>
+ The fact that a result set is a relation means that a query can be used
+ in the definition of another query, becoming a
+ <firstterm>subquery</firstterm>.
+ </para>
+ </glossdef>
+ <glossdef>
+ <para>
</para>
</glossdef>
</glossentry>
</glossdef>
</glossentry>
+ <glossentry id="glossary-routine">
+ <glossterm>Routine</glossterm>
+ <glossdef>
+ <para>
+ A defined set of instructions stored in the database system
+ that can be invoked for execution.
+ A routine can be written in a variety of programming
+ languages. Routines can be
+ <glossterm linkend="glossary-function">functions</glossterm>
+ (including set-returning functions and
+ <glossterm linkend="glossary-trigger">trigger functions</glossterm>),
+ <glossterm linkend="glossary-aggregate">aggregate functions</glossterm>,
+ and <glossterm linkend="glossary-procedure">procedures</glossterm>.
+ </para>
+ <para>
+ Many routines are already defined within <productname>PostgreSQL</productname>
+ itself, but user-defined ones can also be added.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry>
<glossterm>Row</glossterm>
<glosssee otherterm="glossary-tuple" />
Each SQL object must reside in exactly one schema.
</para>
<para>
- The names of SQL objects of the same type in the same schema are enforced
- to be unique.
- There is no restriction on reusing a name in multiple schemas.
- </para>
- <para>
- All system-defined SQL objects reside in schema <literal>pg_catalog</literal>,
- and commonly many user-defined SQL objects reside in the default schema
- <literal>public</literal>,
- but it is common and recommended that other schemas are created to hold
- application-specific SQL objects.
+ All system-defined SQL objects reside in schema <literal>pg_catalog</literal>.
</para>
</glossdef>
<glossdef>
</glossdef>
</glossentry>
+ <glossentry id="glossary-sequence">
+ <glossterm>Sequence (relation)</glossterm>
+ <glossdef>
+ <para>
+ A type of relation that is used to generate values.
+ Typically the generated values are sequential non-repeating numbers.
+ They are commonly used to generate surrogate
+ <glossterm linkend="glossary-primary-key">primary key</glossterm>
+ values.
+ </para>
+ </glossdef>
+ </glossentry>
+
<!-- XXX should define all other isolation levels (and improve this definition)
<glossentry id="glossary-serializable">
<glossterm>Serializable (isolation level)</glossterm>
</glossdef>
</glossentry>
- <glossentry id="glossary-sequence">
- <glossterm>Sequence</glossterm>
- <glossdef>
- <para>
- A type of relation that is used to generate values.
- Typically the generated values are sequential non-repeating numbers.
- They are commonly used to generate surrogate
- <glossterm linkend="glossary-primary-key">primary key</glossterm>
- values.
- </para>
- </glossdef>
- </glossentry>
-
<glossentry id="glossary-shared-memory">
<glossterm>Shared memory</glossterm>
<glossdef>
</glossdef>
</glossentry>
- <glossentry>
- <glossterm>Standby (server)</glossterm>
- <glosssee otherterm="glossary-replica" />
- </glossentry>
-
<glossentry id="glossary-sql-object">
- <glossterm>SQL Object</glossterm>
+ <glossterm>SQL object</glossterm>
<glossdef>
<para>
Any object that can be created with a <command>CREATE</command>
command. Most objects are specific to one database, and are commonly
known as <firstterm>local objects</firstterm>.
- <glossterm linkend="glossary-role">Roles</glossterm>,
- <glossterm linkend="glossary-tablespace">tablespaces</glossterm>,
- replication origins, subscriptions for logical replication, and
- databases themselves are not local SQL objects since they exist
- entirely outside of any specific database;
- they are called <firstterm>global objects</firstterm>.
</para>
<para>
Most local objects belong to a specific
- <glossterm linkend="glossary-schema">schema</glossterm> in their containing database.
+ <glossterm linkend="glossary-schema">schema</glossterm> in their
+ containing database, such as
+ <glossterm linkend="glossary-relation">relations</glossterm> (all types),
+ <glossterm linkend="glossary-function">routines</glossterm> (all types),
+ data types, etc.
+ The names of such objects of the same type in the same schema
+ are enforced to be unique.
+ </para>
+ <para>
There also exist local objects that do not belong to schemas; some examples are
<glossterm linkend="glossary-extension">extensions</glossterm>,
<glossterm linkend="glossary-cast">data type casts</glossterm>, and
<glossterm linkend="glossary-foreign-data-wrapper">foreign data wrappers</glossterm>.
- </para>
+ The names of such objects of the same type are enforced to be unique
+ within the database.
+ </para>
+ <para>
+ Other object types, such as
+ <glossterm linkend="glossary-role">roles</glossterm>,
+ <glossterm linkend="glossary-tablespace">tablespaces</glossterm>,
+ replication origins, subscriptions for logical replication, and
+ databases themselves are not local SQL objects since they exist
+ entirely outside of any specific database;
+ they are called <firstterm>global objects</firstterm>.
+ The names of such objects are enforced to be unique within the whole
+ database cluster.
+ </para>
<para>
For more information, see
<xref linkend="manage-ag-overview"/>.
</glossdef>
</glossentry>
+ <glossentry>
+ <glossterm>Standby (server)</glossterm>
+ <glosssee otherterm="glossary-replica" />
+ </glossentry>
+
<glossentry id="glossary-stats-collector">
<glossterm>Stats collector</glossterm>
<glossdef>
which require storage beyond their definition in the
<glossterm linkend="glossary-system-catalog">system catalog</glossterm>
must belong to a single tablespace.
- Initially, an instance contains a single usable tablespace which is
- used as the default one for all SQL objects, called <literal>pg_default</literal>.
+ Initially, a database cluster contains a single usable tablespace which is
+ used as the default for all SQL objects, called <literal>pg_default</literal>.
</para>
<para>
For more information, see
</glossdef>
</glossentry>
+ <glossentry id="glossary-tps">
+ <glossterm>Transactions per second (TPS)</glossterm>
+ <glossdef>
+ <para>
+ Average number of transactions that are executed per second,
+ totalled across all sessions active for a measured run.
+ This is used as a measure of the performance characteristics of
+ an instance.
+ </para>
+ </glossdef>
+ </glossentry>
+
<glossentry id="glossary-trigger">
<glossterm>Trigger</glossterm>
<glossdef>
A collection of <glossterm linkend="glossary-attribute">attributes</glossterm>
in a fixed order.
That order may be defined by the <glossterm linkend="glossary-table">table</glossterm>
+ (or other <glossterm linkend="glossary-relation">relation</glossterm>)
where the tuple is contained, in which case the tuple is often called a
<firstterm>row</firstterm>. It may also be defined by the structure of a
result set, in which case it is sometimes called a <firstterm>record</firstterm>.
</glossentry>
<glossentry id="glossary-wal-writer">
- <glossterm>WAL writer (process)</glossterm>
- <glossdef>
- <para>
- A process that writes <glossterm linkend="glossary-wal-record">WAL records</glossterm>
- from <glossterm linkend="glossary-shared-memory">shared memory</glossterm> to
- <glossterm linkend="glossary-wal-file">WAL files</glossterm>.
- </para>
- <para>
- For more information, see
- <xref linkend="runtime-config-wal"/>.
- </para>
- </glossdef>
+ <glossterm>WAL writer (process)</glossterm>
+ <glossdef>
+ A process that writes <glossterm linkend="glossary-wal-record">WAL records</glossterm>
+ from <glossterm linkend="glossary-shared-memory">shared memory</glossterm> to
+ <glossterm linkend="glossary-wal-file">WAL files</glossterm>.
+ </para>
+ For more information, see
+ <xref linkend="runtime-config-wal"/>.
+ </para>
+ </glossdef>
</glossentry>
<glossentry id="glossary-window-function">
- <glossterm>Window function</glossterm>
+ <glossterm>Window function (routine)</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-partition">partition</glossterm>.
+ A type of <glossterm linkend="glossary-function">function</glossterm>
+ used in a <glossterm linkend="glossary-query">query</glossterm>
+ that applies to a <glossterm linkend="glossary-partition">partition</glossterm>
+ of the query's <glossterm linkend="glossary-result-set">result set</glossterm>;
+ the function's result is based on values found in
+ <glossterm linkend="glossary-tuple">rows</glossterm> of the same partition or frame.
+ </para>
+ <para>
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 partition.
<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.
+ <glossterm linkend="glossary-db-cluster">database cluster</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>.
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