Administration Guide › Set Up Distribution and Routing › Horizontal Partitioning › Specify Horizontal Partitioning

More information:

set dsa prefix—Define the Prefix of a DSA

Specify Horizontal Partitioning

Specify horizontal partitioning to partition a namespace amongst DSAs.

Follow these steps:

1. Select the attribute whose value you will use to partition the namespace.

   If there are multiple attributes, specify the asterisk (*) character instead of an attribute, as in the following example:

   <c AU><ou Users><* "[hash1(3)=0]">
   

2. Select a horizontal portioning hash that has the most even distribution of data to prevent unbalanced partitions. The following hashing algorithms are supported:
   • hash1—Uses a sum of the uppercase ASCII values as the hash
   • hash2—Uses a CRC-16 hashing algorithm
3. For each DSA in the partitioning, append the string that determines the partition hashing to the prefix.

   You specify the prefix in the knowledge, so use either DXmanager or the set dsa prefix command.

4. Ensure each data DSA has disable-client-binds set to true.

   This ensures requests to go through the router.

Example: Configuration for Horizontal Partition

The configuration of the DSAs is set up as follows:

• Router prefix: <c AU> <ou Users>
• DSA_A prefix: <c AU> <ou Users> <guid "[hash1(3)=0]" >
• DSA_B prefix: <c AU> <ou Users> <guid "[hash1(3)=1]" >
• DSA_C prefix: <c AU> <ou Users> <guid "[hash1(3)=2]" >

From a client point of view all entries appear in the namespace <c AU> <ou Users>.

When the router receives a request, the router applies the specified hash function (hash1) to the specified attribute value (guid) in the request. If the result is zero, it routes the request to DSA_A. If the result is one, it routes the request to DSA_B, and so on.