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CouchDB How to make queries with multiple complex keys

I am trying to make a CouchDB view to obtain some document that is in set 1 and in set 2. For example, when I have a single key I can make some query like:
dbname/_design_doc/viewName?keys=[value1, value2, value3]
and it returns all the documents where it finds either the value1, 2 or 3. What I want is something like this but for a complex key.
For example,
dbname/_design_doc/viewName?keys=[[key1, key12, key13],[key21, key22]]
where key1x is a value for the first key and key2x is a value for the second key, meaning I would like to get every document that has key11 and key21, key11 and key22, key12 and key21, key12 and key22 and so on.
My view is this one:
"twokeys": {
"map": "function(doc) {\n if (doc.uid && doc.hid){\n
emit([doc.uid, doc.hid], doc);\n }\n}"
}
Is this possible?
Thanks in advance

You can query with the keys parameter using complex keys if you follow this answer.
Unfortunately, you can't query both the startkey or the endkey with the keys.

BigQuery WORM work-around for updated data

Using Google's "electric meter" example from a few years back, we would have:
MeterID (Datastore Key) | MeterDate (Date) | ReceivedDate (Date) | Reading (double)
Presuming we received updated info (Say, out of calibration/busted meter, etc.) and put in a new row with same MeterID and MeterDate, using a Window Function to grab the newest Received Date for each ID+MeterDate pair would only cost more if there is multiple records for that pair, right?
Sadly, we are flying without a SQL expert, but it seems like the query should look like:
SELECT
meterDate,
NTH_VALUE(reading, 1) OVER (PARTITION BY meterDate ORDER BY receivedDate DESC) AS reading
FROM [BogusBQ:TableID]
WHERE meterID = {ID}
AND meterDate BETWEEN {startDate} AND {endDate}
Am I missing anything else major here? Would adding 'AND NOT IS_NAN(reading)' cause the Window Function to return the next row, or nothing? (Then we could use NaN to signify "deleted".)

Your SQL looks good. Couple of advices:
- I would use FIRST_VALUE to be a bit more explicit, but otherwise should work.
- If you can - use NULL instead of NaN. Or better yet, add new BOOLEAN column to mark deleted rows.

ElasticSearch Java API to query and return single column instead of the whole json document

While searching using java api in elaticsearch, I would like to retrieve only one column.
Currently when I query using the Java API it returns the whole record like this: [{_id=123-456-7890, name=Wonder Woman, gender=FEMALE}, {_id=777-990-7890, name=Cat Woman, gender=FEMALE}]
The record above correctly matches the search condition shown in th . As shown in the code below:
List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();
SearchRequestBuilder srb = client.prepareSearch("heros")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH);
MatchQueryBuilder mqb;
mqb = QueryBuilders.matchQuery("name", "Woman");
srb.setQuery(mqb);
SearchResponse response = srb.execute().actionGet();
long totalHitCount = response.getHits().getTotalHits();
System.out.println(response.getHits().getTotalHits());
for (SearchHit hit : response.getHits()) {
result.add(hit.getSource());
}
System.out.println(result);
I want only one column to be returned. If I search for name I just want the full names back in a list: "Wonder Woman", "Cat Woman" only not the whole json record for each of them. If you think I need to iterate over the result list of maps in java please propose an example of how to do that in this case.

You can specify the fields to be returned from a search, per documentation. This can be set via SearchRequestBuilder.addFields(String... fields), ie:
SearchRequestBuilder srb = client.prepareSearch("heros")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
.addFields("name");

Better combine both:
use .addFields("name") to tell ES that it needs to return only this
column
use hit.field("name").getValue().toString() to get the result
It is important to use .addFields when you don't need the whole document, but the specific field/s as it will lower the overhead and the network traffic

I figured it out.
List<String> valuesList= new ArrayList<String>();
for (SearchHit hit : response.getHits()) {
result.add(hit.getSource());
valuesList.add(hit.getSource().get("name").toString());
}

The other solutions didn't work for me, hit.getSource() was returning null. Maybe they are deprecated? Not sure. But here was my solution, which FYI can speed things up considerably if you are only getting one field and you are getting lots of results.
Use addFields(Strings) on your SearchRequestBuilder as mentioned, but then when you are getting the values you need to use:
hit.getFields().get( fieldName ).getValue()
or
hit.getFields().get( fieldName ).getValues()
to get a single value or a list of values depending on the field.

How to retrieve the Field that "hit" in Lucene

Maybe I'm really missing something.
I have indexed a bunch of key/value pairs in Lucene (v4.1 if it matters). Say I have
key1=value1 and key2=value2, e.g. as read from a properties file.
They get indexed both as specific fields and into a catchall "ALL" field, e.g.
new Field("key1", "value1", aFieldTypeMimickingKeywords);
new Field("key2", "value2", aFieldTypeMimickingKeywords);
new Field("ALL", "key1=value1", aFieldTypeMimickingKeywords);
new Field("ALL", "key2=value2", aFieldTypeMimickingKeywords);
// then get added to the Document of course...
I can then do a wildcard search, using
new WildcardQuery(new Term("ALL", "*alue1"));
and it will find the hit.
But, it would be nice to get more info, like "what was complete value (e.g. "key1=value1") that goes with that hit?".
The best I can figure out it to get the Document, then get the list of IndexableFields, then loop over all of them and see if the field.stringValue().contains("alue1"). (I can look at the data structures in the debugger and all the info is there)
This seems completely insane cause isn't that what Lucene just did? Shouldn't the Hit information return some of the Fields?
Is Lucene missing what seems like "obvious" functionality? Google and starting at the APIs hasn't revealed anything straightforward, but I feel like I must be searching on the wrong stuff.

You might want to try with IndexSearcher.explain() method. Once you get the ID of the matching document, prepare a query for each field (using the same search keywords) and invoke Explanation.isMatch() for each query: the ones that yield true will give you the matched field. Example:
for (String field: fields){
Query query = new WildcardQuery(new Term(field, "*alue1"));
Explanation ex = searcher.explain(query, docID);
if (ex.isMatch()){
//Your query matched field
}
}

Find out which field matched term in custom score script

I am using a custom score query with a multiMatchQuery. Ultimately what I want is simple and requires little explaination. In my Java Custom Score Script, I want to be able to find out which field a result matched to.
Example:
If I search Starbucks and a result comes back with the name Starbucks then I want to be able to know that name.basic was the field that matched my query. If I search for coffee and starbucks comes back I want to be able to know that tags was the field that matched.
Is there anyway to do this?
Search Query Code:
def basicSearchableSearch(t: String, lat: Double, lon: Double, r: Double, z: Int, bb: BoundingBox, max: Int): SearchResponse = {
val multiQuery = filteredQuery(
multiMatchQuery(t)
//Matches businesses and POIs
.field("name.basic").operator(Operator.OR)
.field("name.no_space")
//Businesses only
.field("tags").boost(6f),
geoBoundingBoxFilter("location")
.bottomRight(bb.botRight.y,bb.botRight.x)
.topLeft(bb.topLeft.y,bb.topLeft.x)
)
val customQuery = customScoreQuery(
multiQuery
)
.script("customJavaScript")
.lang("native")
.param("lat",lat)
.param("lon",lon)
.param("zoom",z)
global.Global.getClient().prepareSearch("searchable")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
.setQuery(customQuery)
.setFrom(0).setSize(max)
.execute()
.actionGet();
}

It's only simple for simple queries. On complex queries, the question which field matched is actually quite nontrivial. So, I cannot think of any efficient way to do it.
Perhaps, you could consider moving your custom score calculation closer to the match. The multi_match query is basically a shortcut for a set of match queries on the same query string combined by a dis_max query. So, you are currently building something like this:
custom_score(
filtered(
dis_max(match_1, match_2, match_3)
)
)
What you can do is to move your custom_score under dis_max and build something like this:
filtered(
dis_max(
custom_score_1(match_1),
custom_score_2(match_2),
custom_score_3(match_3)
)
)
Obviously, this will be a somewhat different query, since dis_max will operate on custom score instead of original score.