SQL/MX 3.1 Installation and Management Guide (H06.23+, J06.12+)

Reorganizing SQL/MX Tables and Maintaining Data
HP NonStop SQL/MX Release 3.1 Installation and Management Guide—663852-001
10-30
Using import to Load Partitions
Managing Indexes to Improve import Performance
A given table with one or more indexes takes much longer to load with import than
does the same table without indexes.
When you perform an
import operation on an SQL/MX table with indexes, you should
first drop all indexes, and then re-create them after the operation completes:
1. Perform a SHOWDDL command on the table and save the SHOWDDL output.
2. Drop all indexes on the table.
3. Perform all required
import operations on the table.
4. After the
import operations complete, refer to the SHOWDDL output to locate all
the CREATE INDEX statements. Update the CREATE INDEX statements and add
the NO POPULATE option.
5. Re-create the indexes.
6. Run POPULATE INDEX to load the data into the indexes.
For information about CREATE INDEX and the NO POPULATE option, see the
SQL/MX Reference Manual.
Managing Triggers to Improve import Performance
Triggers degrade import performance by causing triggered actions to be performed
during the operation. When you perform an
import operation on a table with triggers,
use the
import -D option to disable all triggers. After the data has been inserted,
import automatically enables the disabled triggers.
Managing Data Types to Improve import Performance
import requires additional processing for all date time (DATE, TIME, and
TIMESTAMP), numeric, and decimal data types.
import reads the format file, extracts
the value of the input file, and converts it to a form recognized by NonStop SQL/MX.
For numeric and decimal data types,
import converts the value to the scale and
precision required by NonStop SQL/MX.
Using import to Load Partitions

For range-partitioned tables, you can load the data from a single input file or
several input files into a table’s range partitions. The data in the input file or files
must first be ordered by the table’s range partitioning key.
To perform a parallel
import from a single input file or a serial import from
multiple input files, use the
-F option to specify the number of rows to be skipped
at the beginning of the input file. Use the
-C option to specify the number of rows
to be imported after the skipping occurs. You can use the
-F and -C options to
instruct
import to use the specified rows to load a particular range partition. You