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Tablet

As explained in ScyllaDB in Action

A tablet is a ScyllaDB data-partitioning unit intended to replace vnode-based replication and support finer-grained distribution.

A tablet is a ScyllaDB data-partitioning unit that extends intra-node sharding. It contains a memtable and a collection of SSTables; each shard can contain multiple tablets, while each node still has one shard per CPU core. section 8.3.4 section 8.5

Tablets are intended to replace vnode-based replication and make topology changes more responsive. A tablet load balancer uses Raft to coordinate placement, allowing new nodes to join and take traffic before migration finishes. section 8.3.4

Tablet-based operations change cluster behavior in several practical ways:

  • Adding a node migrates tablets from existing nodes instead of requiring the new node to wait for a complete bootstrap. section 8.3.4
  • An underloaded node can begin relieving a stressed cluster immediately after joining. section 8.3.4
  • The load balancer can also move tablets away from overloaded nodes because tablets are the unit of many cluster operations. section 8.3.4

Expanding a stressed cluster

With vnode-based replication, nodes join serially and require manual orchestration while data bootstraps. With tablets, a new node becomes online immediately, takes traffic, and then receives migrated tablets from more-loaded nodes. section 8.3.4

How ScyllaDB in Action covers it

How deep it goes
Defines tablet contents and explains load-balanced migration, but stops short of detailed configuration or implementation procedures.
Examples
Uses node expansion, stressed-cluster relief, tablet migration, and architecture figures contrasting tablets with vnode-based replication.
What it assumes
Assumes familiarity with nodes, shards, memtables, SSTables, and vnode-based replication while defining tablet structure directly.
What you can do after
Evaluate how tablet-based replication changes node expansion, traffic handling, and load redistribution.
How it connects
Connects tablets with vnode-based replication, sharding, SSTables, Raft, and load balancing.
Cover of ScyllaDB in Action
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of ScyllaDB in Action. The section links point to the parts of the book it draws on.