From f087e44fe4db7996880cf4df982297018d444363 Mon Sep 17 00:00:00 2001 From: Corey Huinker Date: Wed, 12 Feb 2020 04:17:59 +0000 Subject: [PATCH] add glossary page with initial definitions --- doc/src/sgml/filelist.sgml | 1 + doc/src/sgml/glossary.sgml | 540 +++++++++++++++++++++++++++++++++++++ doc/src/sgml/postgres.sgml | 1 + 3 files changed, 542 insertions(+) create mode 100644 doc/src/sgml/glossary.sgml diff --git a/doc/src/sgml/filelist.sgml b/doc/src/sgml/filelist.sgml index 3da2365ea9..504c8a6326 100644 --- a/doc/src/sgml/filelist.sgml +++ b/doc/src/sgml/filelist.sgml @@ -170,6 +170,7 @@ + diff --git a/doc/src/sgml/glossary.sgml b/doc/src/sgml/glossary.sgml new file mode 100644 index 0000000000..1b881690fa --- /dev/null +++ b/doc/src/sgml/glossary.sgml @@ -0,0 +1,540 @@ + + + + Glossary + + This is a list of terms and their definitions in the context of PostgreSQL and databases in general. + + + + Aggregate + + + The act of combining a defined collection of data values into a single value that may not be the same type as the original values. Aggregate functions are most often used with Grouping operations which define the separate sets of data by the common values shared within those sets. + + + + + + Analytic + + + A function whose computed value can reference values found in nearby rows of the same result set. + + + + + + Atomic + + + When referring to the value of an attribute or datum: cannot be broken up into smaller components. + + + When referring to an operation: An event that cannot be partially completed; it must either completely succeed or completely fail. A series of SQL statements can be combined into a transaction, and that transaction is described as atomic. + + + + + + Attribute + + + A typed data element found within a tuple or relation or table. + + + + + + BYTEA + + + A data type for storing binary data. It is roughly analogous to the BLOB data type in other database products. + + + + + + Cast + + + The act of converting of a datum from its current data type to another data type. + + + + + + Check Constraint + + + A type of constraint defined for a relation which restricts the values allowed in one or more attributes. The check constraint can make reference to any attribute in the relation, but cannot reference other rows of the same relation or other relations. + + + + + + Column + + + An attribute found in a table or view. + + + + + + Commit + + + The act of finalizing a transaction within the database. + + + + + + Concurrency + + + The concept that multiple independent operations can be happening within the database at the same time. + + + + + + Constraint + + + A method of restricting the values of data allowed within a relation. Constraints can currently be of the following types: Check Constraint, Unique Constraint, and Exclusion Constraint. + + + + + + Datum + + + The internal representation of a SQL datatype. + + + + + + Delete + + + A SQL command that removes rows from a given table or relation. + + + + + + Exclusion Constraint + + + Exclusion constraints define both a set of columns for matching rows, and rules where values in one row would conflict with values in another. + + + + + + Foreign Data Wrapper + + + A means of representing data outside the local database so that it appears as if it were in local tables. With a Foreign Data Wrapper it is possible to define a Foreign Server and Foreign Tables. + + + + + + Foreign Key + + + A type of constraint defined on one or more columns in a table which requires the value in those columns to uniquely identify a row in the specified table. + + + + + + Foreign Server + + + A named collection of Foreign Tables which all use the same Foreign Data Wrapper and have other configured attributes in common. + + + + + + Foreign Table + + + A relation which appears to have rows and columns like a regular table, but when queried will instead forward the request for data through its Foreign Data Wrapper, which will return results structured according to the definition of the Foreign Table. + + + + + + Function + + + Any pre-defined transformation of data. Many functions are already defined within PostgreSQL itself, but user-defined functions can be added. + + + + + + Grant + + + A SQL command that is used to enable users or roles to access specific objects within the database. + + + + + + Index + + + A relation that contains data derived from a table (or a relation such as a materialized view) that stores the data in a way that makes specific values easier to retrieve. + + + + + + Insert + + + A SQL command used to add new data into a table. + + + + + + Join + + + A technique used with SELECT statements to correlate data in one data set (usually a table) with the data set already defined up to the current point in the SELECT statement. + + + + + + Key + + + A means of identifying a row within a table or relation using values contained within one or more attributes in that table. + + + + + + Lock + + + A mechanism that enables one process to perform actions on a defined object or set of rows within that object while preventing other processes from querying and/or modifying them. + + + + + + Logged + + + A table is considered logged if changes to the table are sent to the WAL. By default, all regular tables are logged. A table can be defined as unlogged either at creation time or via the ALTER TABLE command. The primary use of unlogged tables is for storing transient work data that must be shared across processes, but with a final result stored in logged tables. Temporary tables are always unlogged. + + + + + + Master + + + The server that is considered the authoritative source of information for databases that are linked via replication. + + + + + + Materialized + + + The state of being stored information rather than just a defined means of accessing the information. This term is used in Materialized Views, meaning that the data derived from the view is actually stored on disk separate from the sources of that data. When materialized is used in describing multi-step queries, it means that the data of a given step is stored (in memory, but that storage may spill over onto disk). + + + + + + Materialized View + + + A relation that is defined in the same way that a view is, but it stores data in the same way that a table does. It cannot be modified via INSERT, UPDATE, or DELETE operations. + + + + + + Null + + + A concept of non-existence that is a central tenet of relational database theory. It represents the absence of value. + + + + + + Partition + + + A member of a collection of tables organized to act as if it were itself a single unified table. Each partition is defined to hold a specific subset of data for the partitioned table that cannot overlap with any other partition in that partitioned table. Therefore, no row of data can belong in more than one partition. + + + Partitions have a name and can be queried directly through that name, but they can also be queried implicitly by querying the name of the partitioned table. + + + + + + Primary Key + + + A unique index defined on a table or other relation that also guarantees that all of the attributes within the Primary Key do not have null values. As the name implies, there can be only one Primary Key per table, though it is possible to have multiple unique indexes that also have no null-capable attributes. + + + + + + Procedure + + + A defined set of instructions for manipulating data within a database. Procedures can be written in a variety of programming languages. They may appear like 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 like COMMIT and ROLLBACK. + + + + + + Record + + + A data structure that consists of one or more attributes in a defined order. A record that belongs to a table or other relation is more commonly called a row. + + + + + + Referential Integrity + + + The means of restricting data in one relation so that it must have matching data in another relation. + + + + + + Relation + + + The generic term for all objects in a database that have a name and a list of attributes defined in a specific order. Tables, views, foreign tables, materialized views and indexes are all Relations. + + + + + + Replica + + + A database that is paired with a master database and maintains a copy of some or all of the master database'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 master becomes unavailable. + + + + + + Revoke + + + A command to reduce access to a named set of database objects for a named list of users and roles. + + + + + + Role + + + A collection of access privileges for the database. Roles are themselves a privilege that can be granted to other roles. This is often done for convenience or to ensure completeness when multiple users need the same privileges. + + + + + + Rollback + + + A command to undo all of the operations performed since the beginning of a transaction. + + + + + + Row + + + A tuple or record found within a relation or result set. This term is often used interchangably with Tuple and Record. + + + + + + Schema + + + A named collection of database objects organized to facilitate clarity or security. Most often used in the same way a namespace is used in programming languages. All objects belong to exactly one schema, most commonly public, the default schema. + + + More generically, the term Schema is used to mean all data descriptions (table definitions, constraints, comments) for a given database. + + + + + + Select + + + The command used to query a database. Normally, SELECT commands are not expected to modify the database in any way, but it is possible that Functions invoked within the query could have side effects that do modify data. + + + + + + Serializable + + + Database sessions in a transaction defined as SERIALIZABLE are unable to see changes made to the database by other sessions. In effect, the entire database appears to be frozen in time for the duration of the transaction. + + + + + + Session + + + A connection to the database. Can also be used to describe a series of commands that were issued in the life cycle of a particular connection to the database. + + + + + + Table + + + A collection of tuples (also known as rows or records) having a common data structure (the same number of columns, in the same order, having the same type). A table is the most common form of relation in PostgreSQL. + + + + + + Temporary + + + Temporary tables are tables that exist either for the lifetime of a session or a transaction, as defined at creation time. The data in them is not visible to other sessions, and is not logged. Temporary tables are most often used to store intermediate data for a multi-step data transformation. + + + + + + Transaction + + + A combination of one or more commands that must act as a single atomic command: they all succeed or fail together, and their effects are not visible to other sessions until the transaction is complete. + + + + + + Trigger + + + A function which can be defined to execute whenever a certain operation (INSERT, UPDATE, or DELETE) is applied to that relation. A trigger executes within the same transaction as the statement which invoked it, and if the function fails then the invoking statement also fails. + + + + + + Tuple + + + A collection of attributes in a fixed order. That order may be defined by the table where the Tuple is found, in which case the Tuple is often called a row or record. It may also be defined by the structure of a result set. + + + + + + Unique + + + The state of having a set of columns with no matching values in the same relation. Most often used in the concept of unique indexes. + + + + + + Unique Constraint + + + A rule that defines a set of columns for which no two rows in the table can share the same set of values. + + + + + + Unlogged + + + A relation that is unlogged will not have changes reflected in the WAL, which would enable those changes to be duplicated on a replica, and also enables the change to survive a database crash. + + + + + + Update + + + A command used to modify rows that already exist in a specified table. It cannot create rows nor can it remove them. + + + + + + User + + + A specific case of a role that is entitled to access (log into) the database. + + + + + + User Mapping + + + The translation of user credentials in the local database to credentials in a remote data system defined by a Foreign Data Wrapper. + + + + + + View + + + A relation that is defined by a SELECT statement, but has no storage of its own. Any time a query references a View, the definition of the View is substituted into the query as if the user had typed that subquery instead of the name of the View. + + + + + + Window Function + + + A type of function similar to an aggregate in that it can derive its value from a set of rows in a result set, but still retaining the original source data. + + + + + diff --git a/doc/src/sgml/postgres.sgml b/doc/src/sgml/postgres.sgml index e59cba7997..2183e33bea 100644 --- a/doc/src/sgml/postgres.sgml +++ b/doc/src/sgml/postgres.sgml @@ -278,6 +278,7 @@ &docguide; &limits; &acronyms; + &glossary; -- 2.17.1