[COUCHDB-583] storing attachments in compressed form and serving them in compressed form if accepted by the client

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: Database Core, HTTP Interface

Environment

CouchDB trunk

• Assignee: Unassigned
• Reporter: Filipe David Borba Manana
• Created: 29/Nov/09 15:42
• Updated: 24/Aug/10 11:06
• Resolved: 29/Jan/10 22:44

Description

This feature allows Couch to gzip compress attachments as they are being received and store them in compressed form.

When a client asks for downloading an attachment (e.g. GET somedb/somedoc/attachment.txt), the attachment is sent in compressed form if the client's http request has gzip specified as a valid transfer encoding for the response (using the http header "Accept-Encoding"). Otherwise couch decompresses the attachment before sending it back to the client.

Attachments are compressed only if their MIME type matches one of those listed in a separate config file. Compression level is also configurable in the default.ini file.

This follows Damien's suggestion from 30 November:

"Perhaps we need a separate user editable ini file to specify compressable or non-compressable files (would probably be too big for the regular ini file). What do other web servers do?

Also, a potential optimization is to compress the file while writing to disk, and serve the compressed bytes directly to clients that can handle it, and decompressed for those that can't. For compressable types, it's a win for both disk IO for reads and writes, and CPU on read."

Patch attached.

Issue Links

• is duplicated by: COUCHDB-437 Make compression level configurable, and allow attachments to be compressed