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Custom Sharding With Vitess

Vitess supports a variety of predefined sharding algorithms that can suit different needs. This is achieved by associating a Vindex with your main sharding column. A Vindex essentially provides a mapping function that converts your column value to a keyspace_id. This keyspace_id is then used to decide the target shard. A full description of VSchema and Vindexes can be found here. However, such predefined vindexes will work only if you intend to shard your system using Vitess. What if you're already sharded? Would it be possible to make Vitess accommodate your sharding scheme? This blog intends to cover such a use case.
Vitess is indeed capable of accommodating any sharding scheme because of its pluggable Vindex API. In fact, all the predefined vindexes of Vitess are plug-ins themselves. In order for Vitess to accommodate your sharding scheme, all you have to do is define a Vindex that performs such a mapping.

Use Case
The following example is inspired from my conversations with Simon …