How Adaptive Server distributes partitions on devices

When you issue an alter table...partition command, Adaptive Server creates the specified number of partitions in the table and distributes those partitions over the database devices in the table’s segment. Adaptive Server assigns partitions to devices so that they are distributed evenly across the devices in the segment.

Table 5-1 illustrates how Adaptive Server assigns 5 partitions to 3, 5, and 12 devices, respectively.

**Table 5-1: Assigning partitions to segments**
Partition ID	Device (D) Assignments for Segment With
Partition ID	3 Devices	5 Devices	12 Devices
Partition 1	D1	D1	D1, D6, D11
Partition 2	D2	D2	D2, D7, D12
Partition 3	D3	D3	D3, D8, D11
Partition 4	D1	D4	D4, D9, D12
Partition 5	D2	D5	D5, D10, D11

Matching the number of partitions to the number of devices in the segment provides the best I/O performance for parallel queries.

You can partition tables that use the text, image, or Java off-row data types. However, the columns themselves are not partitioned—they remain on a single page chain.