SQL/MX Glossary

Glossary

HP NonStop SQL/MX Glossary—523732-002

Glossary-28

program independence

program independence. The ability to change an application without changing the

database. Contrast with data independence.

programmatic SQL. The SQL statements and directives that can be embedded in a host-

language program; the application programming interface for SQL/MX. Contrast with

MXCI.

publish. To insert rows of data into a queue or channel by using an INSERT or UPDATE

statement.

query. Generally, a request for data from the database; specifically, the execution of a

SELECT statement, which requests columns and rows from one or more tables and

views. In the context of the SQL/MX optimizer, a query is a request for data access

through any DML statement.

query execution plan. See access plan and execution plan.

query expression. A syntactical element that defines a derived table. A derived table can

be used as a table reference in the FROM clause of a SELECT statement. See also

table reference.

query optimization. The selection by the optimizer of the best available query execution

plan for each DML statement, including the access path, join order, type of join, sort

strategy, and so forth.

query plan caching. A feature of the SQL/MX compiler that provides the ability to cache

the plans of certain queries.

queue. A database table used by applications specifying stream access to dequeue newly

published entries. The entries are removed from the table. Only a single subscriber

receives a new entry.

range partitioning. A method of distributing records among partitions based on ranges of

key values. With range partitioning, you define key ranges for each partition, and each

record is assigned to the partition whose range includes the value of its partitioning

key. Compare with hash partitioning.

range of INTERVAL fields. The subset of fields, called an INTERVAL qualifier, that

compose a value of type INTERVAL. The range can include either year-month or day-

time fields, but not both. Some sample ranges are YEAR, DAY TO HOUR, and

MINUTE TO SECOND.

RDF. See Remote Duplicate Database Facility (RDF).