MONGO 3.4 Shard Cluster Series Six: detailed Configuration database

This series wants to share with you the following chapters (I will continue to update the (^ω^)):

1. One of the MONGO 3.4 Shard Cluster Series: A brief discussion on shard cluster

2, MONGO 3.4 Shard Cluster Series two: Building a shard cluster--Hash shard

3, MONGO 3.4 Shard Cluster Series three: Building a shard cluster--hash shard + security

4, MONGO 3.4 Shard cluster series four: Building a shard cluster--Hash shard + security + Zone

5, MONGO 3.4 Shard Cluster series five: detailed balancer

6, MONGO 3.4 Shard Cluster Series Six: detailed Configuration database

7, MONGO 3.4 Shard Cluster series seven: Configuration database management

8, MONGO 3.4 Shard Cluster series eight: Shard management

This is a theoretical chapter.

The configuration database is used primarily for internal use, and you should not manually insert or store data during normal operation.

The following describes the set of config databases (this is in MongoDB 3.4 and does not guarantee that other versions are the same.) Can only be said for reference)

1, Actionlog

2, Changelog

A document that stores metadata for each changed shard collection.

Each document in the Changelog collection contains the following fields:

_id values are:

Server host name of the server where this data is saved.

clientaddr A string that contains the client address, and a MONGOs instance that initializes the change.

Time A isodate timestamp that reflects when the change occurred.

What The type of change that reflects the record. The possible values are:

• • • • • Dropcollection
        • Dropcollection.start
        • Dropdatabase
        • Dropdatabase.start
        • Movechunk.start
        • Movechunk.commit
        • Split
        • Multi-split

NS the namespace in which the change occurred.

The details contain more details about the changes. The structure of the details document depends on the type of change.

3, Chunks

Information stored in each block in the cluster

The _id value is: The namespace of the collection to which the < block belongs >-< The Shard key >-< block range minimum value >

The namespace of the collection to which the NS block belongs

min and Max describe the range of stored values for a block

Shard identify shards of "owning" blocks in a cluster

4, collections

Information for each shard collection stored in the cluster

The _id value is: The namespace of the < collection >

lastmod Last modified time

Dropped whether to drop the collection

Key Sharding key

Unique is the only

5, Databases

Stores the document for each database in the cluster and tracks whether the database has shards enabled.

_id Database name

Whether the partitioned is fragmented

The name of the primary shard after the Primary Shard

6, Lockpings

Tracks the active components in a shard cluster.

7, Locks

Storing distributed locks

_id objects with distributed locking action

who enables this distributed lock client or internal program

process to enable the distributed lock

When to enable the distributed lock

Why this distributed lock is enabled

8, migrations

9, Mongos

Stores each document of the MONGOs instance associated with the cluster. The MONGOs instance sends pings to all members of the cluster every 30 seconds so that the cluster can verify that the MONGOs is active.

_id host Name: Port

Ping shows the time of the last ping

up reports the last ping uptime

mongoversion running the MONGOs version

10, Settings

Equalizer Settings

11, shards

A document represents a shard in a cluster

_id Shard Name

host hostname, if the Shard is a replica set, displays the name of the replica set, then displays a slash, and then a comma-delimited list of host names for each member of the replica set

Tags Save an array of regions to which the Shard is assigned

12. Tags

Save information for each zone range in the cluster

_id includes the namespace of the collection, the minimum value of the zone

The namespace of the NS Collection

min. min area

max value of region

Name of the Tag area

13. Version

Saves the current metadata version number. This collection contains only one document.

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The above information, most of which is reference to the official website of the information, expressed thanks.

https://docs.mongodb.com/manual/reference/config-database/

MONGO 3.4 Shard Cluster Series Six: detailed Configuration database