SQL/MP Glossary

Glossary
Compaq NonStop™ SQL/MP Glossary—429832-001
Glossary-14
hybrid hash join
hybrid hash join. A hash join method that retains as much as possible of the inner table in
memory but divides rows of both inner and outer tables into clusters that reside on disk
and can be processed in memory. Ordering is not preserved. See also simple hash join.
implicit correlation name. A table or view name for which no correlation name is specified
in the FROM clause of a SELECT statement. Contrast with explicit correlation name
.
index. An alternate access path (alternate key) to a table that differs from the primary access
path (primary key) defined for the table at creation time. A NonStop SQL/MP index,
stored in a file, includes columns for the primary key and the alternate key.
index predicate. A predicate evaluated on rows in an index by the disk process or the file
system.
indicator variable. A numeric variable associated with a column that allows null values. A
host language program uses an indicator variable to indicate whether a column contains
a null value.
inner join. A query that concatenates rows from all tables and views named in the FROM
clause of a SELECT statement and discards all rows that do not satisfy the predicates
specified in a WHERE or ON clause. Contrast with outer join
.
inner query. A subquery nested within a statement or another subquery. See also outer query
and subquery.
inner table. In the evaluation of a join, the table that the optimizer accesses last.
inoperable execution plan. An execution plan whose execution would cause an error,
incorrect query results, or the corruption of the database. An inoperable execution plan
is semantically incorrect and must be recompiled before it can execute correctly.
Contrast with operable execution plan
.
Inspect product. An interactive source-level and machine-level debugger that enables users
to interrupt and resume program execution and to display and modify variables.
integrity. See data integrity
or integrity constraint.
integrity constraint. A condition that must be met before rows can be inserted or columns
updated in the table for which the constraint is defined. This condition helps to maintain
data integrity. See also constraint
and data integrity.
INTERVAL data type. A data type for year-month and day-time values that represent
intervals of time. INTERVAL data consists of formatted values for one or more of the
following fields: either YEAR, MONTH, and DAY or HOUR, MINUTE, SECOND, and
FRACTION.
INTERVAL literal. A literal that has the INTERVAL data type.