SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
D-20
DDL (Data Definition Language) Statements
You cannot use DCOMPRESS on a file with a clustering key. You cannot use the
COLLATE option on a key column if you will be using DCOMPRESS.

The file system compresses keys by eliminating the leading characters duplicated
from one key to the next and replacing them with a one-byte count of the duplicate
characters:
Key compression can actually require an additional byte per record. It saves the
most space when many key values have similar beginnings.

Relative and entry-sequenced files always have the NO DCOMPRESS attribute,
although key compression has no effect on them.
DDL (Data Definition Language) Statements
DDL (Data Definition Language) is the set of SQL statements that define, delete, or
modify the SQL definition of an object or catalog. They can also change the
authorization to use an object or catalog.
DDL Statements
Series of Uncompressed
Keys
Same Keys,
Compressed
JONES, JANE 0JONES, JANE
JONES, JOHN 8OHN
JONES, SAM 7SAM
Statement Description (page 1 of 2)
ALTER CATALOG
Statement
Alters security for a catalog
ALTER COLLATION
Statement
Renames or alters security for a collation
ALTER INDEX
Statement
Renames, adds, drops, or moves partitions, or alters security or
other attributes of an index
ALTER PROGRAM
Statement
Renames or alters security of an SQL program in a Guardian file
ALTER TABLE
Statement
Renames, alters security of file attributes, or enables or disables
similarity checks for a table; also adds columns to a table and
adds, drops, or moves partitions of a table
ALTER VIEW
Statement
Renames, alters security, or enables or disables similarity checks
for a view; also adds column headings to a view
COMMENT Statement
Writes a comment about an SQL object to a catalog
CONTINUE Statement
Specifies a COMMIT option for a DDL operation ready to enter its
final phase
CREATE CATALOG
Statement
Creates a catalog