SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
L-9
Limits
SQL defines a lock limit for the number of row locks that a program can own. The
limit is internal to SQL/MP software. If a program exceeds the limit and the locks
cannot be upgraded to table locks, the program receives an error message.

MAXEXTENTS
The maximum number of extents allowed is 944 for a Format 1 partition. This
number is decreased if the extent size (primary or secondary) is very large, such
as a secondary extent size of 2,000 pages.
For Format 2 partitions, the maximum number of extents allowed is 919. This
number can change per RVU and without notice.

Partition size
For Format 1 partitions, the maximum partition size that SQL/MP software can
support is approximately 2.1465 gigabytes. This number is determined by using
this formula: 2**31 - 1 - 1 megabyte. The 1 megabyte of space is for internal use.
The formula for applying the limit to a partition is:
PRIM + ( SEC * (MAXEXT -1) ) <= 2.1465 gigabytes
where
PRIM
is the primary extent size in bytes
SEC
is the secondary extent size in bytes
MAXEXT
is the maximum number of extents
For Format 2 partitions, the maximum partition size is limited to the size of the disk,
up to one terabyte.

Partitions per index or table, extended partition array
Typically, if the primary key of the index or table is between 10 and 50 bytes, the
maximum number of partitions allowed ranges from approximately 900 (for the
smaller key size) down to 400 (for the larger key size).
The maximum number of index partitions depends on the key size; if the primary
key of a key-sequenced table is between approximately 10 and 50 bytes and the
index key size is also between 10 and 50 bytes, the maximum number of partitions
typically ranges from 674 (for keys of 10 bytes) to 246 (for keys of 50 bytes).
The actual calculation of the limit is complex and depends on such factors as disk
label space and the message size of the NonStop operating system.