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The "Why are all Views in a single Index" page has been changed by BenjaminYoung: http://wiki.apache.org/couchdb/Why%20are%20all%20Views%20in%20a%20single%20Index Comment: initial text by Filipe Manana New page: = Why are all Views in a single Index = by [[http://fdmanana.wordpress.com/|Filipe Manana]] Each view basically corresponds to 1 btree. All live in the same file. Other than saving the number of file descriptors and possibly, some OS page caching benefits, and simpler code, I don't think there's more benefits. Now the real benefit comes when in the same ddoc you have 2 (or more) views with the same map function. For example: {{{ view1: { "map": "function(doc) { if (doc.type === 'foo') { emit(key, value); } }", "reduce": "_count" } }}} {{{ view2: { "map": "function(doc) { if (doc.type === 'foo') { emit(key, value); } }", "reduce": "_sum" } }}} Here view1 and view2 have exactly the same map function. Would they be in different ddocs, we would have 2 btrees (in 2 different files) for exactly the same data. Now, if they're in the ddoc, we use 1 btree only but with 2 different reduce values - this saves disk space and update time (1 only update 1 btree instead of 2) - of course, this is easy only because we use 1 single file for a ddoc with multiple views.
