I have a two or more collection in mongodb that are replicated to solr indexes using mongo-solr connectors. For the sake of explaining my problem I am facing lets take the traditional example of employee & department example (I know it's Document oriented DB & I can embed department to employee document, but please allow me to explain my question with this trivial example):
Employee document:
{
"_id": ObjectId(..),
"firstName": "John",
"lastName": "David",
"departMent": ObjectId(..) - a DBRef for department document
}
Department document:
{
"_id": ObjectId(..),
"departmentName": "Marketing"
}
Let's say that above two documents are linked in employee document using the department's object id ref. Now mongo-solr connector replicated these structures as it is and let's assume all of the fields are indexed and stored.
Now here is my question ( & the problem):
If I search the solr index by employee firstName (or lastName), I should get back results in such a way that the solr search response should include the "departmentName" instead of the Department ObjectId reference and that this should happen over a single search request originating from a client.
How do I do this using Solr apis?
Thanks in advance.
The ideal solution of course (from Solr perspective) would be to store the data in Solr in the denormalized form. However, if that is not a viable option, you could take a look at the Join query Parser.
https://cwiki.apache.org/confluence/display/solr/Other+Parsers#OtherParsers-JoinQueryParser
You would be performing a query along the lines of (not tested):
q={!join from=department to=departmentName}lastName:David AND departmentName:Marketing
Related
I'm trying to filter the data from my database using this code:
fdb.orderByChild("title").startAt(searchquery).endAt(searchquery+"\uf8ff").addValueEventListener(valuelistener2);
My database is like this:
"g12" : {
"Books" : {
"-Mi_He4vHXOuKHNL7yeU" : {
"title" : "Technical Sciences P1"
},
"-Mi_He50tUPTN9XDiVow" : {
"title" : "Life Sciences"
},
"-Mi_He51dhQfl3RAjysQ" : {
"title" : "Technical Sciences P2"
}}
While the code works, it only returns the first value that matches the query and doesn't fetch the rest of the data even though it matches.
If I put a "T" as my search query, I just get the first title "Technical Sciences P1 " and don't get the other one with P2
(Sorry for the vague and common question title, it's just I've been looking for a solution for so long)
While the codes works, it only returns the first value that matches the query
That's the expected behavior since Firebase Realtime Database does not support native indexing or search for text fields in database properties.
When you are using the following query:
fdb.orderByChild("title").startAt(searchquery).endAt(searchquery+"\uf8ff")
It means that you are trying to get all elements that start with searchquery. For example, if you have a title called "Don Quixote" and you search for "Don", your query will return the correct results. However, searching for "Quix" will yield no results.
You might consider downloading the entire node to search for fields client-side but this solution isn't practical at all. To enable full-text search of your Firebase Realtime Database data, I recommend you to use a third-party search service like Algolia or Elasticsearch.
If you consider at some point in time to try using Cloud Firestore, please see the following example:
Is it possible to use Algolia query in FirestoreRecyclerOptions?
To see how it works with Cloud Firestore but in the same way, you can use it with Firebase Realtime Database.
All of the examples I'm finding online have very simple document IDs, but what do you do if you're auto-generating all your IDs (as the docs say you should)? For example, I want to query the date when the user was created. The document ID for this is below, but I've just copy-pasted it from the Firestore console. How would I know the document ID so that I may query any user's info? Note that I will be have a users, groups, usergroups, etc... There will be quite a few collections, each using the auto-ID feature. I would need to be able to update any row in any collection.
val docRef = db.collection("users").document("9AjpkmJdAdFScZaeo8FV45DT54E")
docRef.get()
.addOnSuccessListener { document ->
if (document != null) {
Log.e("Query", "Data: ${document.data}")
} else {
Log.e("Query", "Document is null")
}
}
.addOnFailureListener { exception ->
Log.e("Query", "Failure")
}
If you have data to query, that should all be stored as fields in the documents. Don't put that data in the ID of the documents - use field values.
You can filter documents in a collection using "where" clauses as shown in the documentation. What you're showing here isn't enough to go with in to make specific recommendations. But you definitely want to think about your queries ahead of time, and model your data to suit those queries.
If you need to update a document, you must first query for it, then update what you find from the query. This is extremely common, as Firestore does no provide any SQL-like "update where" queries that both locate and update data in the same command.
I'm using elasticsearch 6.x version with ingest plugin to let me query inside document.
I managed to insert record with attachment document and I'm able to query it against various fields.
When I query the content of the file I'm doing this:
boolQuery.filter(new MatchPhrasePrefixQueryBuilder("attachment.content", "St. Anna Church"))
It works, but I want now to make query with this field: "Church Wall People" where basically it's not a complete phrase, I want back all the documents that contain the words Church, Wall and People.
SQL Query : SELECT DISTINCT column FROM table_name WHERE [condition]
We want to apply same query in elastic search, where i can find distinct values of column in search result.
For example we have index of users (userindex) field is information where school name or company name of the user in indexed.
let there are users with same school name. i want all the distinct school name from the index
As keety stated in the comments, one possibility is to use a terms aggregation like the following:
curl localhost:9200/users/_search?pretty=1 -d
{
"aggs": {
"schools": {
"terms": {
"field": "schoolname"
}
}
}
}
Depending on your use case this might already be enough. But you should keep in mind that the buckets ES returns for the aggregation are somewhat limited and possibly inaccurate concerning pagination and counts.
See https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html
I am new to mongoDB. I was told to use mongoDB to my photo management web app. I am not able to understand mongoDB's basic concept. The documents.
What is documents in mongoDB?
j = { name : "mongo" };
t = { x : 3 };
In mongoDB website they told that the above 2 lines were 2 documents.
But till this time i thought .txt, .doc .excel... etc. were documents.(This may be funny, but i am really in need of understanding its concepts!)
How do you represent a txt file for example example.txt in mongoDB?
What is collection?
Collection of documents is known as "Collections in mongoDB"
How many collections i can create?
All documents were shared in all collections
Finnaly i come to my part, How shall i represent images in mongoDB?
With the help of tutorials i learned to store and retrieve images from mongoDB using java!!
But, without the understanding of mongoDB's concepts i cannot move further!
The blog's and articles about mongoDB is pretty interesting. But still i am not able to understand its basic concepts!!!
Can anyone strike my head with mongoDB!!??
Perhaps comparing MongoDB to SQL would help you ...
In SQL queries work against tables, columns & rows in set-based operations. There are pre-defined schema's (and hopefully indexes) to aid the query processor (as well as the querier!)
SQL Table / Rows
id | Column1 | Column2
-----------------------
1 | aaaaa | Bill
2 | bbbbb | Sally
3 | ccccc | Kyle
SQL Query
SELECT * FROM Table1 WHERE Column1 = 'aaaaa' ORDER BY Column2 DESC
This query would return all the columns in the table named Table1 where the column named Column1 has a value of aaaaa it then will order the results by the value of Column2 and return the results in descending order to the client.
MongoDB
In MongoDB there are no tables, columns or rows ... instead their are Collections (these are like tables) and Documents inside the Collections (like rows.)
MongoDB Collection / Documents
{
"_id" : ObjectId("497ce96f395f2f052a494fd4"),
"attribute1" : "aaaaa",
"attribute2" : "Bill",
"randomAttribute" : "I am different"
}
{
"_id" : ObjectId("497ce96f395f2f052a494fd5"),
"attribute1" : "bbbbb",
"attribute2" : "Sally"
}
{
"_id" : ObjectId("497ce96f395f2f052a494fd6"),
"attribute1" : "ccccc",
"attribute2" : "Kyle"
}
However there is no predefined "table structure" or "schema" like a SQL table. For example you can see the second document in this collection has an attribute called randomAttribute that none of the other documents have.
This is just fine, it won't affect our queries but does allow for for some very powerful things ...
The data is stored in a format called BSON which is very close to the Javascript JSON standard. You can find out more at http://bson.org/
MongoDB Query
SELECT * FROM Table1 WHERE Column1 = 'aaaaa' ORDER BY Column2 DESC
How would we do this same thing in MongoDB's Shell?
> db.collection1.find({attribute1:"aaaaa"}).sort({attribute2:-1});
Perhaps you can already see how similar a MongoDB query really is to SQL (while appearing quite different.) I have some posts up on http://learnmongo.com which might help you as well.
MongoDB is a document database : http://en.wikipedia.org/wiki/Document-oriented_database