Size Limitations

Couchbase Server specifies size-limitations that affect server usage and implementation.

Table of Size Limitations

The following limitations are imposed by Couchbase Server.

Limit Default Value Description

Limit	Default Value	Description
Max key length	250 bytes	The maximum length of the document ID (key).
Max value size	20 MB	The maximum size of the JSON document.
Max buckets per cluster	10	The maximum number of buckets in a cluster. See section for information on how to update the maximum number of buckets in a cluster.
Max view key size	4096 bytes	The maximum size of the key (first attribute) in the `emit()` function.
Max doc size for indexing	20 MB	The maximum size of a document that can be indexed. The default value is set to 20 MB to ensure that all documents get indexed. In Couchbase Server version 2.x and earlier, the view engine enforced a limit of 1MB on documents that can be indexed. As a result, when the size of a document exceeded the limit, the view engine (in version 2.x) did not index that document.
Max key-value size per document	1 MB	The maximum byte size allowed to be emitted for a single document and per view. This value is the sum of the sizes of all emitted keys and values. If a document emits a key-value pair that exceeds the specified maximum key-value size per document, an error is logged and that document is not indexed.
Max concurrent key-value connections	30,000	Each Couchbase Data node allows up to 30,000 concurrent key-value connections by default.
Function timeout	1000 ms	The maximum duration (in milliseconds) to execute all the MapReduce functions in a design document against a single document (map function) or against a list of map values or reductions (reduce or rereduce function). If the execution time for a document exceeds the specified value, the execution is aborted and that document is not indexed.
Sub-document path length	1024 bytes	The maximum length of a sub-document path that may be used in a sub-document operation.
Sub-document path nesting level	32	The maximum number of levels a path may reference in a sub-document operation.

Max key length

250 bytes

The maximum length of the document ID (key).

Max value size

20 MB

The maximum size of the JSON document.

Max buckets per cluster

The maximum number of buckets in a cluster. See section for information on how to update the maximum number of buckets in a cluster.

Max view key size

4096 bytes

The maximum size of the key (first attribute) in the emit() function.

Max doc size for indexing

20 MB

The maximum size of a document that can be indexed. The default value is set to 20 MB to ensure that all documents get indexed.

In Couchbase Server version 2.x and earlier, the view engine enforced a limit of 1MB on documents that can be indexed. As a result, when the size of a document exceeded the limit, the view engine (in version 2.x) did not index that document.

Max key-value size per document

1 MB

The maximum byte size allowed to be emitted for a single document and per view. This value is the sum of the sizes of all emitted keys and values.

If a document emits a key-value pair that exceeds the specified maximum key-value size per document, an error is logged and that document is not indexed.

Max concurrent key-value connections

30,000

Each Couchbase Data node allows up to 30,000 concurrent key-value connections by default.

Function timeout

1000 ms

The maximum duration (in milliseconds) to execute all the MapReduce functions in a design document against a single document (map function) or against a list of map values or reductions (reduce or rereduce function). If the execution time for a document exceeds the specified value, the execution is aborted and that document is not indexed.

Sub-document path length

1024 bytes

The maximum length of a sub-document path that may be used in a sub-document operation.

Sub-document path nesting level

The maximum number of levels a path may reference in a sub-document operation.