SQL/MX Glossary

HP NonStop SQL/MX Glossary—523732-002
Glossary-1
Glossary
A
3GL. Third-generation language. A high-level programming language such as C or Java.
4GL. A nonprocedural, high-level language, such as structured query language (SQL), that
is used for database management systems.
aborted transaction. A transaction that was backed out (undone). See also transaction
access option. A DML statement option that affects the consistency of data accessed by
the statement execution. See also read uncommitted access, read committed access,
serializable access, repeatable read access.
access path. The method by which data is accessed. SQL/MX provides primary access
and alternate index access. Primary access can be sequential (entire base table
scanned) or keyed (rows read based on clustering key value). Alternate index access
can be index only (all columns required by the query are included in the index) or
access to the base table through an index.
access plan. A database access method for a single compiled DML statement. The
EXPLAIN function is a table-valued stored function that generates a result table
describing an access plan for the statement. See also execution plan.
alias mapping. A mapping from a logical object name to a physical NonStop operating
system location. Alias mappings allow three-part logical names to identify SQL/MP
tables and views. In Release 1.8 and earlier releases, this mapping was stored in a
special SQL/MP table created by SQL/MX called MPALIAS. Starting with Release 2.0,
mappings are created in existing catalogs and schemas and are stored in SQL/MX
metadata as SQL/MX aliases that consist of the catalog, schema, and name. See also
object name and MPALIAS table.
alternate key. See index.
anchor file. A simple text file with ASCII tokens that identifies the volume where the system
metadata resides. The anchor file resides in the NonStop operating system space
$SYSTEM.ZSQLMX.MXANCHOR.
ANSI external name. A name defined when objects are created or altered. ANSI SQL
objects have both external and internal names. When objects are created or altered in
A B C D E F G H I J K L
M N O P Q R S T U V W