# Cloud Bigtable

This tutorial explains what is a Cloud Bigtable in GCP.

Cloud Bigtable is a sparsely populated table that can scale to billions of rows and thousands of columns, enabling you to store terabytes or even petabytes of data. A single value in each row is indexed; this value is known as the row key. Bigtable is ideal for storing large amounts of single-keyed data with low latency.

Things to retain:

• A Bigtable is managed by an instance. A Bigtable instance is a container for data.

• The Instances have one or more clusters (we cannot have 2 clusters in the same zone).

• Each cluster has at least 1 node.

• A Table belongs to an instance and not to the cluster or node.

• Storage Type dictates where the data is stored i.e. SSD or HDD. Choice of SSD or HDD storage for the instance is permanent.

• Clusters handle the requests sent to a single Bigtable instance.

• Each cluster belongs to a single Bigtable instance, and an instance can have up to 4 clusters.

• Bigtable instances with only 1 cluster do not use replication.

• If multiple clusters within an instance, Bigtable automatically starts replicating the data by keeping separate copies of the data in each of the clusters’ zones and synchronizing updates between the copies.

• Each cluster in an instance has 1 or more nodes, which are the compute resources that Bigtable uses to manage the data.

• Each node in the cluster handles a subset of the requests to the cluster.

• Bigtable separates the Compute from the Storage. Data is never stored in nodes themselves.

• Behind the scenes, Bigtable splits all the data in a table into separate tablets. Tablets are stored on disk, separate from the nodes but in the same zone as the nodes. A tablet is associated with a single node.

• A Bigtable cluster can be scaled by adding nodes which would increase

  • the number of simultaneous requests that the cluster can handle
  • the maximum throughput of the cluster.