SQL/MP Glossary

Glossary
Compaq NonStop™ SQL/MP Glossary—429832-001
Glossary-15
invalid object
invalid object. A table, view, index, or collation that is unusable because its file label is not
consistent with its catalog entries, or because the object contains data that does not
satisfy constraints on the object or that is inconsistent with a related object.
invalid program. A program that is marked as SQL invalid because an invalidating
operation occurred to at least one of its execution plans. NonStop SQL/MP marks the
program as invalid in its file label (if available) and in the PROGRAMS table in the
catalog. See also invalidating operation
.
invalidating operation. An operation that causes an execution plan to become invalid and
consequently the program file that contains the plan to be marked as invalid. Any of the
following operations can be invalidating:
•
A DDL operation performed on an SQL object. NonStop SQL marks any programs
that reference the changed object as invalid.
•
An operation performed on the program file itself. For example, copying a program
file invalidates the new file and marks it as not SQL sensitive. In addition, host-
language compiling, binding, or accelerating a registered SQL program deletes it
from the catalog it is registered in if the new version of the program is written to the
same object file that held the previous version.
•
A change after explicit SQL compilation to a DEFINE referenced by an SQL
statement in the program.
In some cases, the similarity check and the SQLCOMP CHECK INOPERABLE
PLANS option can prevent the invalidation of a program.
ISO 8859/N character set. Nine single-byte (8-bit) character sets (ISO 8859/1 through ISO
8859/9). The ASCII (7-bit) character set is a subset of each of these character sets.
join. A database operation that combines two or more tables into a single logical table so that
data can be selected from all the tables at once. Types of joins include inner join, left
join, and outer join. Join methods include hash join, merge join, and nested join.
join predicate. A predicate that identifies and compares columns in a join operation.
Kanji character set. A double-byte character set for the Japanese language, also known as
the Shift-JIS character set.
key predicate. A predicate that specifies begin-key conditions, end-key conditions, or both to
narrow the range of searching for single-table and join queries. Such conditions reduce
the number of rows fetched; this reduction of physical I/Os can improve performance.
key prefix. A leading (leftmost) contiguous set of columns in the key.
key-sequenced file. A file in which each new record is stored in sequence by primary-key
value. Rows of a table stored in a key-sequenced file can be updated or deleted. Contrast
with entry-sequenced file
and relative file. See also key-sequenced table.