[
https://issues.apache.org/jira/browse/COUCHDB-2259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14042806#comment-14042806
]
Robert Newson commented on COUCHDB-2259:
----------------------------------------
couchdb documents are cacheable but it's important to revalidate with the host
server (in case it's changed). This is still caching, the body can be served
from the cache if the host server returns a 304 response.
> CouchDB 1.6.0 returns wrong Vary
> --------------------------------
>
> Key: COUCHDB-2259
> URL: https://issues.apache.org/jira/browse/COUCHDB-2259
> Project: CouchDB
> Issue Type: Bug
> Security Level: public(Regular issues)
> Components: HTTP Interface
> Reporter: Kaj Nielsen
>
> CouchDB documents are immutable. Even when deleted, a new revision is
> assigned to the document (and the _deleted flag is set).
> As such, HTTP requests for specific document revisions, by use of the
> If-Match header, are cacheable.
> HTTP requests with no revision numbers are not cacheable.
> Therefore, for If-Match requests, the correct caching headers are:
> - Vary: If-Match
> - no Cache-Control header (or a default value, eg. 24hrs)
> And for "non-revisioned" requests, the correct headers are:
> - Vary: If-Match
> - Cache-Control: must-revalidate
> However:
> > GET /db/doc HTTP/1.1
> > Host: localhost:5984
> > If-Match: 167-37f82fdbfdc49d38b1c66815deb1e338
> >
> < HTTP/1.1 200 OK
> < Server: CouchDB/1.6.0 (Erlang OTP/R15B01)
> < ETag: "167-37f82fdbfdc49d38b1c66815deb1e338"
> < Date: Tue, 24 Jun 2014 22:34:20 GMT
> < Content-Type: text/plain; charset=utf-8
> < Content-Length: 649
> < Cache-Control: must-revalidate
> <
> ...
> As seen above, even when requesting a very specific revision of a document,
> CouchDB still requests revalidation with "must-revalidate".
> Thereby making modern HTTP caches unable to take advantage of caching the
> (potentially large) body of HTTP transactions that are perfectly cacheable
> (because the request include If-Match).
> Also, CouchDB incorrectly does not discern the request from a non-revisioned
> request with regards to the "must-revalidate" cache-control header.
> "must-revalidate" should not be set on responses where If-Match is present in
> the request.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
