SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
L-6
Limits
Limits
NonStop SQL/MP has limits on the size and number of objects, on the size of columns,
on file attributes, and on other items you use with NonStop SQL/MP.
SQL uses information stored in file labels and special records in the disk volume
directory that contain information about a table, view, partition, or catalog. As a result,
some limits depend on the size of file labels, which have a block size of 4096.
NonStop SQL/MP limits are summarized in this alphabetic list of items:

Base tables per view
A view definition can include a maximum of 16 base tables in a FROM clause.

Block size
The largest allowed block size is 4096 bytes.

Clustering key length
The sum of the column lengths for the columns of the key cannot exceed 247
bytes. SQL appends an 8-byte SYSKEY column to the columns specified for the
clustering key, making the maximum actual physical key length 255.

Column heading
The SQLCI report writer imposes a maximum of 50 lines on a column heading. Any
new-line character following the 49th one is text and does not create a new line.
Column headings are defined with the HEADING clause of the CREATE or ALTER
statements for a table or view.

Columns per index
The maximum number of columns allowed for an index is 254 minus the number of
columns in the primary key of the underlying table.

Columns per table
The maximum number of columns allowed per table depends on the column
definitions with these restrictions:

The sum of the lengths of the columns in a row must not exceed the maximum
row length (see the Row length item later in this subsection). In determining the
column length for a varying-length character column, use the maximum
declared length plus two bytes. For example, suppose that you declare a
VARCHAR column of the maximum row length. The limit for the number of
columns in this situation is one.
For each column that can contain null values, add two bytes to the column
length.

The description of the table must fit in the file label. The number of columns
that fits depends on the data types of the columns and on the presence of