3.13. Miscellaneous Parameters¶

3.13.1. Configuration of Attachment Storage¶

[attachments]¶

compression_level¶

Defines zlib compression level for the attachments from 1 (lowest, fastest) to 9 (highest, slowest). A value of 0 disables compression:

[attachments]
compression_level = 8

compressible_types¶

Since compression is ineffective for some types of files, it is possible to let CouchDB compress only some types of attachments, specified by their MIME type:

[attachments]
compressible_types = text/*, application/javascript, application/json, application/xml

3.13.2. Statistic Calculation¶

[stats]¶

interval¶

Interval between gathering statistics in seconds:

[stats]
interval = 10

3.13.3. UUIDs Configuration¶

[uuids]¶

algorithm¶

Changed in version 1.3: Added utc_id algorithm.

CouchDB provides various algorithms to generate the UUID values that are used for document _id’s by default:

[uuids]
algorithm = sequential

Available algorithms:

random: 128 bits of random awesome. All awesome, all the time:

{
    "uuids": [
        "5fcbbf2cb171b1d5c3bc6df3d4affb32",
        "9115e0942372a87a977f1caf30b2ac29",
        "3840b51b0b81b46cab99384d5cd106e3",
        "b848dbdeb422164babf2705ac18173e1",
        "b7a8566af7e0fc02404bb676b47c3bf7",
        "a006879afdcae324d70e925c420c860d",
        "5f7716ee487cc4083545d4ca02cd45d4",
        "35fdd1c8346c22ccc43cc45cd632e6d6",
        "97bbdb4a1c7166682dc026e1ac97a64c",
        "eb242b506a6ae330bda6969bb2677079"
    ]
}

sequential: Monotonically increasing ids with random increments. The first 26 hex characters are random, the last 6 increment in random amounts until an overflow occurs. On overflow, the random prefix is regenerated and the process starts over.

{
    "uuids": [
        "4e17c12963f4bee0e6ec90da54804894",
        "4e17c12963f4bee0e6ec90da5480512f",
        "4e17c12963f4bee0e6ec90da54805c25",
        "4e17c12963f4bee0e6ec90da54806ba1",
        "4e17c12963f4bee0e6ec90da548072b3",
        "4e17c12963f4bee0e6ec90da54807609",
        "4e17c12963f4bee0e6ec90da54807718",
        "4e17c12963f4bee0e6ec90da54807754",
        "4e17c12963f4bee0e6ec90da54807e5d",
        "4e17c12963f4bee0e6ec90da54808d28"
    ]
}

utc_random: The time since Jan 1, 1970 UTC, in microseconds. The first 14 characters are the time in hex. The last 18 are random.

{
    "uuids": [
        "04dd32b3af699659b6db9486a9c58c62",
        "04dd32b3af69bb1c2ac7ebfee0a50d88",
        "04dd32b3af69d8591b99a8e86a76e0fb",
        "04dd32b3af69f4a18a76efd89867f4f4",
        "04dd32b3af6a1f7925001274bbfde952",
        "04dd32b3af6a3fe8ea9b120ed906a57f",
        "04dd32b3af6a5b5c518809d3d4b76654",
        "04dd32b3af6a78f6ab32f1e928593c73",
        "04dd32b3af6a99916c665d6bbf857475",
        "04dd32b3af6ab558dd3f2c0afacb7d66"
    ]
}

utc_id: The time since Jan 1, 1970 UTC, in microseconds, plus the utc_id_suffix string. The first 14 characters are the time in hex. The uuids/utc_id_suffix string value is appended to these.

{
    "uuids": [
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]"
    ]
}

Note

Impact of UUID choices: the choice of UUID has a significant impact on the layout of the B-tree, prior to compaction.

For example, using a sequential UUID algorithm while uploading a large batch of documents will avoid the need to rewrite many intermediate B-tree nodes. A random UUID algorithm may require rewriting intermediate nodes on a regular basis, resulting in significantly decreased throughput and wasted disk space space due to the append-only B-tree design.

It is generally recommended to set your own UUIDs, or use the sequential algorithm unless you have a specific need and take into account the likely need for compaction to re-balance the B-tree and reclaim wasted space.

utc_id_suffix¶

New in version 1.3.

The utc_id_suffix value will be appended to UUIDs generated by the utc_id algorithm. Replicating instances should have unique utc_id_suffix values to ensure uniqueness of utc_id ids.

[uuid]
utc_id_suffix = my-awesome-suffix

max_count¶

New in version 1.5.1.

No more than this number of UUIDs will be sent in a single request. If more UUIDs are requested, an HTTP error response will be thrown.

[uuid]
max_count = 1000

3.13.4. Vendor information¶

[vendor]¶

New in version 1.3.

CouchDB distributors have the option of customizing CouchDB’s welcome message. This is returned when requesting GET /.

[vendor]
name = The Apache Software Foundation
version = 1.5.0

3.13.5. Content-Security-Policy¶

[csp]¶

Experimental support of CSP Headers for /_utils (Fauxton).

enable¶

Enable the sending of the Header Content-Security-Policy:

[csp]
enable = true

header_value¶

You can change the default value for the Header which is sent:

[csp]
header_value = default-src 'self'; img-src *; font-src *;

3.13.6. Configuration of Database Purge¶

[purge]¶

max_document_id_number¶

New in version 3.0.

Sets the maximum number of documents allowed in a single purge request:

[purge]
max_document_id_number = 100

max_revisions_number¶

New in version 3.0.

Sets the maximum number of accumulated revisions allowed in a single purge request:

[purge]
max_revisions_number = 1000

index_lag_warn_seconds¶

New in version 3.0.

Sets the allowed duration when index is not updated for local purge checkpoint document. Default is 24 hours:

[purge]
index_lag_warn_seconds = 86400