Oracle9i™ Development by Example

Hash Partitioning

Hash partitioning is similar to range partitioning except that the partition key is hashed and the rows spread evenly across the assigned tablespaces. This kind of partitioning is convenient when the distribution of the rows might not be even, or no well-defined grouping of the key fields exists (as in the situation of the date field in the range partitioning example). Figure 15.2 illustrates how the tablespaces might appear for a hash-partitioned table, and Listing 15.3 shows the syntax needed to support the example in Figure 15.2. Notice no MAXVALUE clause exists with hash partitioning.

Figure 15.2. ST_SALES hash partitioned table.

NOTE

Hashing algorithm— Takes a key field and applies a calculation to it that always equals ...