level-index
Create an index on some data. For more complex use-cases, use level-mapped-index or map-reduce
Example
point the dates of posts back to the the post.
var levelup = require('levelup')
var sublevel = require('level-sublevel')
var index = require('level-index')
var db = sublevel(levelup('/tmp/level-index-test', {encoding: 'json'}))
var postByDate = index(db,
'postByDate', //name.
function (key, value, emit) {
var obj = value;
console.log(obj.date);
emit(obj.date, {
id : key,
subject : obj.subject,
content : obj.content,
date : obj.date
});
}
);And then query it with a normal read-stream.
var through = require('through')
postByDate.createReadStream({
start : fromDate.toISOString(),
end : (new Date()).toISOString()
})
.pipe(through(console.log))A strong benefit of this module is that the indexes are generated atomically (in a batch) with the triggering insert, so you can request the index back immediately after it has been inserted.
Gotchas
Use this module for things where the index doesn't change. for example - the date a blog was posted on can never change. how tall some one is can change, but their birthday can't change.
For indexes on changing data, use/write another module.
License
MIT