[GitHub] garrensmith opened a new issue #126: [RFC] Implement Partitions api

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garrensmith opened a new issue #126: [RFC] Implement Partitions api 
URL: https://github.com/apache/couchdb-nano/issues/126
 
 
   We are currently adding partition support to CouchDB https://github.com/apache/couchdb/pull/1605
   This document details how I think the api for partitions should work for nano.
   
   Partitions allow a user to store related documents into a `partition` within CouchDB. Using the new partition endpoints this would then allow a user to query only documents in a specific partition. This leads to much faster query time as CouchDB only needs to fetch the documents from a subset of the shards for a db.
   
   To store a document in a partition a user prefixes an id with the partition name e.g `{_id: "partition1:my-doc", "field": "one"}` and `{_id: "partition2:my-doc", "field": "one"}`.
   
   Then using a tradional view to query the document you would use these endpoints:
   Map/Reduce:
   `/my-db/_partition/partition1/_design/my-view`
   
   And for Mango:
   `/my-db/_partition/partition1/_find`
   
   The idea around partitions, which I've hopefully conveyed really quickly above, is that data in a partition is quite separate and when a database is partitioned a user would work with each partition separately. I would like to reflect that kind of thinking in the api. So I propose that we would add a new function called `partition` which accepts a partition name and returns an object for you to query a specific partition. Hopefully the below example explains it.
   
   ```js
   await nano.db.create('db1', {partition: true});
   const db = nano.use('db1');
   await db.insert({
         views: {
           aview: {
             map: "function(doc) {\n  if (doc.group) {\n    emit([doc.some, doc.group], 1);\n }\n}",
             reduce: "_count"
           }
         }
       }
   }, _design/example-query);
   
   
   db.insert({some: "field"}, 'partition1:doc1');
   db.insert({some: "field2"}, 'partition1:doc2');
   db.
   // This goes in partition 2
   db.insert({some: "field2"}, 'partition2:doc1');
   
   const partition1 = db.partition('partition1');
   
   // This will only return doc with id `partition1:doc1`
   const docs = await partition1.find({
      selector: {
        some: "field"
      }
   });
   
   const docs2 = await partition1.view("example-query", "aview", {include_docs: true});
   
   const partition2 = db.partition('partition2');
   // A view can be used for each partition
   const docsFromPartition2 = await partition1.view("example-query", "aview", {include_docs: true});
   ```
   
   The new partition object would support all the `.find` and `.view` options to query with and internally would remember the name of the partition to use when querying.
   
   Currently we don't support _all_docs or changes.
   
   
   

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