NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
L-11
Limits
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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.
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The bigger your partitions are, the fewer you can specify.
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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.
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Predicates per query
The maximum number of predicates allowed in a NonStop SQL/MP query is
approximately 290. The exact limit depends on the combination of predicates and
column data types.
This is a Guardian operating system limitation.
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Prepared statements
You can have up to 20 prepared statements in an SQLCI session. (Programs can
have more prepared statements.)
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Primary key
See Syskeys
on page S-90, Clustering Keys on page C-26, or User-Defined Keys on
page U-17.
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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.) A header is 32 bytes for key-sequenced
tables and 22 bytes for relative and entry-sequenced tables. In addition, there are
two bytes overhead for each row in a block.
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Statement length
The maximum length of a NonStop SQL/MP statement is 32,767 characters,
including blanks.
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Subquery nesting
Queries can be nested a maximum of 16 levels, including the outermost query.
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SYSKEY value
The value range allowed for a SYSKEY (system-defined primary key) is 0 through
4,294,963,199 for the 4-byte primary key used in a table with relative or entry-
sequenced file organization; the range is 0 through 2**63-1 for the 8-byte primary
key (actually, a timestamp) used in a table with key-sequenced file organization.
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Tables per query