SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
L-11
Limits

Partitions per index or key-sequenced table, format 2 enabled partition array
Typically, if the primary key of the index or key-sequenced table is between 10 and
50 bytes, the maximum number of partitions allowed can be from approximately
800 (for the smaller key size) down to 390 (for the larger key size).
If the key of an index is between 10 and 50 bytes, the maximum number of index
partitions is typically between approximately 620 (for keys of 10 bytes) and 238 (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.
When you create or alter a table or index with a large number of partitions, the
PARTNS catalog table and associated IXPART01 index might become full. To
correct the situation, distribute object and partition definitions across multiple
catalogs.
Actual limits depend upon the definition of the SQL tables and indexes, but the
PARTNS and IXPART01 catalog tables can contain approximately 500,000 rows.
Each table or index with N partitions stores N**2 rows of information in the
PARTNS catalog table. Thus, three tables of 400 partitions each can be defined in
a single catalog.
DDL and DML operations on tables or indexes that have large numbers of
partitions might return file-system error 31 or 34 because of insufficient memory in
the process file segment (PFS) used by the SQL file system. Actual limits depend
upon the definition of the SQL tables and indexes and the SQL statement being
executed, but memory limitations typically appear when a table or index has 400 or
more partitions.