Composite views in couchbase

问题

I'm new to Couchbase and am struggling to get a composite index to do what I want it to. The use-case is this:

• I have a set of "Enumerations" being stored as documents
• Each has a "last_updated" field which -- as you may have guessed -- stores the last time that the field was updated
• I want to be able to show only those enumerations which have been updated since some given date but still sort the list by the name of the enumeration

I've created a Couchbase View like this:

function (doc, meta) {
   var time_array;
   if (doc.doc_type === "enum") {
      if (doc.last_updated) {
         time_array = doc.last_updated.split(/[- :]/);
      } else {
         time_array = [0,0,0,0,0,0];
   }
   for(var i=0; i<time_array.length; i++) { time_array[i] = parseInt(time_array[i], 10); }
   time_array.unshift(meta.id);
   emit(time_array, null);
}

}

I have one record that doesn't have the last_updated field set and therefore has it's time fields are all set to zero. I thought as a first test I could filter out that result and I put in the following:

startkey = ["a",2012,0,0,0,0,0]
endkey = ["Z",2014,0,0,0,0,0]

While the list is sorted by the 'id' it isn't filtering anything! Can anyone tell me what I'm doing wrong? Is there a better composite view to achieve these results?

回答1:

In couchbase when you query view by startkey - endkey you're unable to filter results by 2 or more properties. Couchbase has only one index, so it will filter your results only by first param. So your query will be identical to query with:

startkey = ["a"]
endkey = ["Z"]

Here is a link to complete answer by Filipe Manana why it can't be filtered by those dates.

Here is a quote from it:

For composite keys (arrays), elements are compared from left to right and comparison finishes as soon as a element is different from the corresponding element in the other key (same as what happens when comparing strings à la memcmp() or strcmp()).

So if you want to have a view that filters by date, date array should go first in composite key.

来源：https://stackoverflow.com/questions/17076267/composite-views-in-couchbase