Skip to content

Update sharding-introduction.txt #1119

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

Update sharding-introduction.txt #1119

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 8 additions & 8 deletions source/core/sharding-introduction.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -61,23 +61,23 @@ clusters <sharded cluster>`.
.. include:: /images/sharded-cluster-production-architecture.rst

Sharded cluster has the following components: :term:`shards <shard>`,
:term:`routers <mongos>` and :term:`config servers <config database>`.
:term:`query routers <mongos>` and :term:`config servers <config database>`.

**Shards** store the data. To provide high availability and data
consistency, in a production sharded cluster, each shard is a
:term:`replica set` [#dev-only-shard-deployment]_. For more
information on replica sets, see :doc:`Replica Sets
</core/replication>`.

**Routers**, or :program:`mongos` instances, interface with client
**Query Routers**, or :program:`mongos` instances, interface with client
applications and direct operations to the appropriate shard or
shards. The router processes and targets operations to shards and then
shards. The query router processes and targets operations to shards and then
returns results to the clients. A sharded cluster can contain more
than one router to divide the client request load. A client sends
requests to one routers. Most sharded cluster have many routers.
than one query router to divide the client request load. A client sends
requests to one query router. Most sharded cluster have many query routers.

**Config servers** store the cluster's metadata. This data contains a
mapping of the cluster's data set to the shards. The router uses this
mapping of the cluster's data set to the shards. The query router uses this
metadata to target operations to specific shards. Production sharded
clusters have *exactly* 3 config servers.

Expand Down Expand Up @@ -138,7 +138,7 @@ Performance Distinctions between Range and Hash Based Partitioning
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Range based partitioning supports more efficient range queries. Given
a range query on the shard key, the router can easily determine which
a range query on the shard key, the query router can easily determine which
chunks overlap that range and route the query to only those shards
that contain these chunks.

Expand Down Expand Up @@ -185,7 +185,7 @@ Balancing

The :ref:`balancer <sharding-balancing-internals>` is a background
process that manages chunk migrations. The balancer runs in all of the
routers in a cluster.
query routers in a cluster.

When the distribution of a sharded collection in a cluster is uneven,
the balancer process migrates chunks from the shard that has the
Expand Down