SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
L-12
Limits

Partitions per relative or entry-sequenced table
This type of limit on partitions for a table is affected by the same restrictions that
apply to key-sequenced tables with standard partition arrays. Additional restrictions
also apply because of dependencies on the number and size of extents and on
primary key values.
These details can help you estimate the maximum number of partitions allowed for
relative or entry-sequenced tables:

When you partition a table, NonStop SQL/MP evenly distributes all possible
rows (identified by primary key value) into the partitions in both primary and
secondary extents using the MAXEXTENTS attribute value to determine the
number of extents and the EXTENTS attribute to determine extent sizes.
(Relative files have SYSKEY values that begin at 0 and increment by 1.
Entry-sequenced files have SYSKEY values based on the block number.)

SQL assigns rows to partitions until it either runs out of primary key values or
runs out of space declared for the table. You cannot specify partitions that
would require primary key values greater than 4,294,963,199.

The bigger your partitions are, the fewer you can specify.

When you define a partition for a relative or entry-sequenced table, you do not
specify the range of rows to be stored in the partition. SQL determines where
rows are stored.

Predicates per query
The maximum number of predicates allowed in an SQL/MP query is approximately
290, a Guardian operating system limitation. The exact limit depends on the
combination of predicates and column data types.

Prepared statements
You can have up to 20 prepared statements in an SQLCI session. (Programs can
have more prepared statements.)

Primary key
See Syskeys on page S-90, Clustering Keys on page C-28, or User-Defined Keys
on page U-16.

Row length
Row length is the sum of the lengths of the columns of a table. For each column
that can contain null values, add 2 bytes to the column length when computing this
sum. The length of a varying-length character column is its maximum declared
length plus 2 bytes.
The maximum row length is the block size minus space for a file header. (The
BLOCKSIZE attribute controls block size.)