flimzy commented on a change in pull request #252: Suggested edit to make clear what a quorum actually represents. URL: https://github.com/apache/couchdb-documentation/pull/252#discussion_r172105690
########## File path: src/cluster/theory.rst ########## @@ -32,12 +32,21 @@ As you see in ``etc/default.ini`` there is a section called [cluster] When creating a database you can send your own values with request and thereby override the defaults in ``default.ini``. -The number of copies of a document with the same revision that have to be read -before CouchDB returns with a ``200`` is equal to a half of total copies of -the document plus one. It is the same for the number of nodes that need to -save a document before a write is returned with ``201``. If there are less -nodes than that number, then ``202`` is returned. Both read and write numbers -can be specified with a request as ``r`` and ``w`` parameters accordingly. +In clustered operation, a quorum must be reached before CouchDB returns a 200 +for a fetch, or 201 for a write operation. A quorum is defined one plus half the +number of "relevant copies". "Relevant copies" is defined slightly differently +for read and write operations. + +For read operations, the number of relevant copies is the number of +currently-accessible shards holding the requested data, meaning that in the case +of a failure or network partition, the number of relevant copies may be lower +than the number of replicas in the cluster. The number of read copies can be +set with the rparameter. + +For write operations the number of relevant copies is always `n`, the number of +replicas in teh cluster. For write operations, the number of copies can be set Review comment: teh -> the ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
