Sharding and zones

In TeselaDB you do not need a shard key: each collection is split into ranges by size and load. If your application already uses shard keys or zones, the MongoDB commands work the same.

Shard key

sh.shardCollection("shop.orders", { customer: 1, _id: 1 });

shardCollection (ranged, hashed or compound) reorders the collection so each document is stored by its shard key. reshardCollection and refineCollectionShardKey change it online.

Uniqueness

_id is unique across the whole cluster and a unique index does not need the shard key as a prefix. In MongoDB it is only unique within each shard.

Zones

A zone restricts the replicas of some shard key intervals to some nodes, for example to keep the data of European customers on EU machines. The shard name of each node is the one listShards shows:

sh.addShardToZone("<shard>", "eu");
sh.updateZoneKeyRange("shop.orders", { region: "eu" }, { region: "eu~" }, "eu");

Chunks and balancer

split, moveChunk, mergeChunks, balancerStart, balancerStop and the config database (config.chunks, config.shards) have MongoDB's shape. Each node appears as a shard in listShards.