SQL/MP Glossary

Glossary
Compaq NonStop™ SQL/MP Glossary—429832-001
Glossary-10
exclusive access
exclusive access. See repeatable access.
exclusive lock. A lock exclusion mode in which only the holder of the lock can access the
locked data, except with browse access. Contrast with shared lock
.
execution characteristics. The characteristics of an SQL statement’s execution plan that
have no effect on the statement’s semantics. Examples include a plan’s performance,
node autonomy, resource use, and locking strategy.
execution plan. An execution method, including the semantics and execution characteristics,
for a single compiled SQL statement. The SQL compiler stores the execution plan in the
program file during explicit compilation, and the SQL executor uses the plan to execute
the SQL statement at run time. Compiled programs typically include many plans. Each
plan can be operable or inoperable, optimal or not optimal, and valid or invalid.
execution-time name resolution. The resolution of a name of an SQL object or catalog in an
SQL statement performed at statement execution time rather than at SQL load time or
during explicit SQL compilation.
executor. The NonStop SQL/MP component that executes compiled SQL statements that
access database tables, views, or catalogs. The executor executes a DML statement by
using the query execution plan chosen by the optimizer, and it executes a DDL
statement by sending a request to the catalog manager to update the appropriate catalog
tables and to make or to modify the object. If necessary, the executor calls the SQL
compiler to recompile an invalid program or statement.
executor predicate. A predicate that must be evaluated by the executor.
executor server process. See ESP (executor server process)
.
EXPLAIN plan. See query execution plan
.
explicit correlation name. A correlation name specified in the FROM clause of a SELECT
statement as an alternate name for a table or a view. Contrast with implicit correlation
name.
explicit SQL compilation. The SQL compilation of a program initiated by running the SQL
compiler (SQLCOMP). The SQL compiler generates a program file and marks the file
as SQL sensitive and SQL valid. Contrast with automatic SQL recompilation.
exploded record format. A COBOL-like layout of all values in a row in the form of a fixed-
length record in which each VARCHAR column is padded with spaces to its maximum
length and preceded by its logical length (not including the filler spaces). Filler spaces
also precede values of data type VARCHAR, NUMERIC, SMALLINT, INTEGER,
LARGEINT, and PIC COMP when needed to align the values on word boundaries.
Contrast with packed record format
.
expression. A representation of a value. An expression has a data type and can have an
associated character set or collation.