- Aggregate function
+ Aggregate function (routine)
A function that
+
+ Analytic function
+
+
+
Analyze (operation)
(Don't confuse this term with the ANALYZE option
to the command.)
+ For more information, see
+ .
+
-
- Analytic function
-
-
-
Atomic
An element with a certain name and data type found within a
- tuple or
- table.
+ tuple.
- -directory">
- Data directory
+ base">
+ Database
- The base directory on the filesystem of a
- server that contains all
- data files and subdirectories associated with an
- instance (with the
- exception of tablespaces).
- The environment variable PGDATA is commonly used to
- refer to the
- data directory.
-
- An instance's storage
- space comprises the data directory plus any additional tablespaces.
+ A named collection of
+ local SQL objects.
For more information, see
- storage-file-layout"/>.
+ manage-ag-overview"/>.
- atabase">
- Database
+ b-cluster">
+ Database cluster
- A named collection of
- SQL objects.
+ A collection of databases and global SQL objects,
+ and their common static and dynamic metadata.
+ Sometimes referred to as a
+ cluster.
- For more information, see
- .
+ In
PostgreSQL, the term
+ cluster is also sometimes used to refer to an instance.
+ (Don't confuse this term with the SQL command CLUSTER.)
+
+ Data directory
+
+ The base directory on the filesystem of a
+ server that contains all
+ data files and subdirectories associated with a
+ database cluster
+ (with the exception of
+ tablespaces,
+ and optionally WAL).
+ The environment variable PGDATA is commonly used to
+ refer to the data directory.
+
+ A cluster's storage
+ space comprises the data directory plus any additional tablespaces.
+
+ For more information, see
+ .
+
+
+
+
Data page
- Foreign table
+ Foreign table (relation)
A relation which appears to have
- Function
+ Function (routine)
- Any defined transformation of data. Many functions are already defined
- within
PostgreSQL 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
+ SELECT.
+ Certain functions can return
+ sets; those are
+ called set-returning functions.
+
+ Functions can also be used for
+ triggers to invoke.
For more information, see
- Index
+ Index (relation)
A relation that contains
data derived from a table
- (or relation types
- such as a materialized view).
+ or materialized view.
Its internal structure supports fast retrieval of and access to the original
data.
Instance
- A set of databases and accompanying global SQL objects that are stored in
- the same data directory
- in a single server.
- If running, one
+ A group of backend and auxiliary processes that communicate using
+ a common shared memory area. One
postmaster process
- manages a group of backend and auxiliary processes that communicate
- using a common shared memory
- area. Many instances can run on the same
+ manages the instance; one instance manages exactly one
+ database cluster
+ with all its databases. Many instances can run on the same
server
as long as their
TCP ports do not conflict.
The instance handles all key features of a
DBMS:
read and write access to files and shared memory,
assurance of the
ACID properties,
- connections to client processes,
+ connections to
+ client processes,
privilege verification, crash recovery, replication, etc.
- In
PostgreSQL, the term
- cluster is also sometimes used to refer to an instance.
- (Don't confuse this term with the SQL command CLUSTER.)
-
Join
- An
SQL keyword used in
SELECT statements for
- combining data from multiple relations.
+ An operation and
SQL keyword used in
+ queries
+ for combining data from multiple
+ relations.
A means of identifying a row within a
table or
- relation by
+ other relation by
values contained within one or more
attributes
- in that table.
+ in that relation.
-
- Log record
-
- Archaic term for a WAL record.
-
-
-
-
Logged
+
+ Log record
+
+ Archaic term for a WAL record.
+
+
+
+
Master (server)
- Materialized view
+ Materialized view (relation)
A relation that is
- defined in the same way that a view
- is, but stores data in the same way that a
+ defined by a SELECT statement
+ (just like a view),
+ but stores data in the same way that a
table does. It cannot be
modified via INSERT, UPDATE, or
DELETE operations.
One of several disjoint (not overlapping) subsets of a larger set.
+
+
In reference to a
partitioned table:
- In reference to a window function:
+ In reference to a window function
+ in a query,
a partition is a user-defined criterion that identifies which neighboring
- rows can be considered by the
- function.
+ rows
+ of the query's result set
+ can be considered by the function.
- Partitioned table
+ Partitioned table (relation)
A relation that is
-
- Primary (server)
-
- When two or more databases
- are linked via replication,
- the server
- that is considered the authoritative source of information is called
- the primary,
- also known as a master.
-
-
-
-
Primary key
+
+ Primary (server)
+
+ When two or more databases
+ are linked via replication,
+ the server
+ that is considered the authoritative source of information is called
+ the primary,
+ also known as a master.
+
+
+
+
- Procedure
+ Procedure (routine)
- A defined set of instructions for manipulating data within a
- database.
- A procedure can
- be written in a variety of programming languages. They are
- similar to functions,
- but are different in that they must be invoked via the CALL
- command rather than the SELECT or PERFORM
- 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 COMMIT and ROLLBACK.
+ They are invoked via the CALL command.
For more information, see
indexes are all relations.
+ More generically, a relation is a set of tuples; for example,
+ the result of a query is also a relation.
+
Class is an archaic synonym for
relation.
Result set
- A data structure transmitted from a
- backend process to
- a client upon the
- command, usually a SELECT but it can be an
+ A relation transmitted
+ from a backend process
+ to a client upon the
+ completion of an
SQL command, usually a+ SELECT but it can be an
INSERT, UPDATE, or
DELETE command if the RETURNING
- clause is specified. The data structure consists of zero or more
- rows with the same ordered set of
- attributes.
+ clause is specified.
+
+ The fact that a result set is a relation means that a query can be used
+ in the definition of another query, becoming a
+ subquery.
+
+
+
+
+ Routine
+
+ 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
+ functions
+ (including set-returning functions and
+ trigger functions),
+ aggregate functions,
+ and procedures.
+
+ Many routines are already defined within
PostgreSQL+ itself, but user-defined ones can also be added.
+
+
+
+
Row
Each SQL object must reside in exactly one schema.
- 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.
-
- All system-defined SQL objects reside in schema pg_catalog,
- and commonly many user-defined SQL objects reside in the default schema
- public,
- 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 pg_catalog.
+
+ Sequence (relation)
+
+ 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
+ primary key
+ values.
+
+
+
+
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