SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
L-7
Limits
default values. File label restrictions can reduce the maximum number of
columns allowed to as few as 128.

Columns per view
The maximum number of columns allowed for a view is between 200 and 400,
depending on the size of the column definitions. The size of the column definitions
depends on the data types of the columns and the complexity and number of
operators that define the selection of rows. The descriptions of the columns of the
view must fit in a file label.

Comments
A comment line in a catalog table cannot exceed 132 characters. The maximum
number of lines allowed is 10,000.

Constraint definition
The search condition that defines a constraint must be less than 3,000 bytes.
The code generated for the combined search conditions of all constraints
associated with a table must be less than 31,000 bytes.

Cursors
One object file can have up to a billion cursors. Assuming 300 bytes for each SQL
statement object, 4 megabytes would hold 12,000 cursors. If the cursor definitions
are complex or have large names, or there are many input or output variables, the
limit becomes smaller.

Data length
Fixed-length character data has a minimum length of one character. Varying-length
character data has a minimum length of 0 characters, but the length field is two
bytes. The maximum length of a character column depends on the file organization
of the table that contains the column, on whether the character set associated with
the column is a single or double-byte character set, and on whether the data type
specifies a fixed of varying length.
A column that allows null values requires two extra bytes.
For clustering keys and system-defined primary keys, SQL requires 8 bytes for a
system-defined key called SYSKEY.
A string literal can be as long as a character column. For more information, see
Data Types on page D-1.
Data Type Key-Sequenced Relative or Entry-Sequenced
Single-byte unvarying 4061 4072
Single-byte VARYING 4059 4070
Double-byte unvarying 2030 2036
Double-byte VARYING 2029 2035