CouchbaseView-创新互联

Couchbase index: called view -- virtually another document build via map-reduce function

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Map function:
Call emit() to generate a key-value pair
Reduce function:
Optional (disabled by reduce=false)
Used to calculate count, sum etc

Query View:

Call ViewResult.success() to check whether view execution is successful. Call ViewResult.error() to see error details
Set ViewQuery.debug(true) generate statistics information. Retrieved by ViewResult.debug()
Remember to call ViewQuery.development(true) if a development View has not been published as production view
For dev mode, full design doc name is:   _design/dev_[designdoc name], to query it, just use designdoc name
   If you specify designdoc name as dev_xxx, you get error:
   com.couchbase.client.java.error.ViewDoesNotExistException: View does not exist
   If you specify designdoc name as /dev_xxx or _design/dev_xxx, you get error:
   {"error":"bad_request","reason":"p_w_uploads not supported in Couchbase"}
To query composite key, do not use ViewQuery.key(String), which causes additional quote to be added to the key, add get a json format error:
invalid UTF-8 JSON {error,garbage_after_value}
Uses ViewQuery.key(JsonArray) and JsonArray.from(Object[] array). Each element of array must of correct type (String or Long)
To view complete query as url parameter after encoding: use ViewQuery.toString()
Suppose a view composes of 3 field [a, b, c], it is possible to find documents by [a, b] only and [a, c] only using that view. ViewQuery.startKey([a, b, null]) and ViewQuery.startKey([a, null, c])
Sort query result: ViewQuery.desc()
References:
http://docs.couchbase.com/admin/admin/Views/views-writing.html
http://docs.couchbase.com/admin/admin/Views/views-querySample.html

Bulk operations:

Couchbase java sdk supports bulk operation, which improves performance for read/write for a number of documents
References:
http://docs.couchbase.com/developer/java-2.1/documents-bulk.html

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CouchbaseView-创新互联

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