Let's say we have two index types: members and restaurants. Both contain city attribute.
I want to filter members (e.g. by name) and would like to include list of restaurant names from the members' hometown/city in the results.
Is it possible to do this using just one ES query? I guess it should be similar to DB join.
Thanks.
ES doesn't have the concepts of joins. This is due to it being an index rather than a relational database. Your best best to make two calls. One to get the member's documents, then another to get the restaurants.
Unless you have odd circumstances, this should still be very efficient.
Related
In our application we offer list queries with sorting and filtering and now we were discussing if we should also offer single item queries with the id as parameter.
I've googled a bit and found that very often both queries, list and single item, are implemented.
I'm just wondering why. Wouldn't/Shouldn't a single item query with id as parameter be the same as a list query filtered for id? In both cases the UI should be able to select all properties throughout the graph, right?
Why would the backend care to offer a single item query when the list is already sufficient?
Looking for best practices here.
We are a housing association with a large CRM system (2016 & SP1). We have a new requirement that requires our users to be able to search for people who are current (ie not previous) occupants or residents or who are not residents (eg contractors)
For this purpose, we need to search the Person entity which has a related Tenancy entity. Person has TenancyType field with possible (option set) values Occupant, Resident, Contractor. Tenancy has TenancyStatus field with possible (text) values Current and Previous.
We tried using the following filter criteria in the quick view on the Person entity:
thinking that it would return all people who are not previous residents. However we noticed that it would filter out contractors because contractors do not have related tenancy records.
We needed to change the criteria to return all contractors OR all residents and occupants with no previous tenancy. So we changed it to the following:
at which point we got stuck because we noticed that it was not possible to AND together the second and the third conditions as the third one is a related entity.
We are wondering what the best way is to achieve the above bearing in mind that we do not want a separate view for each condition, eg one for residents, one for none residents, etc.
Any help or suggestion is greatly appreciated.
It is not possible to do this with a single query.
Instead, you can use two queries. If you do not want to do that, then using reports (as suggested by Alex) or a BI-solution would be other possibilities.
Thanks to everyone here who spent time answering my question. The following describes the correct answer:
https://community.dynamics.com/crm/f/117/p/241352/666651#666651
I have a search database of car models: "Nissan Gtr", "Huynday Elantra", "Honda Accord", etc...
Now I also have a user list and the types of cars they like
user1 likes: carId:1234, carId:5678 etc...
Given user 1 I would like to return all the cars he likes, it can be 0 to even hundreads.
What the best way to model this in Solr or potentially another "nosql" system that can help with this problem.
I'm using Solr but I have the opportunity to use another system if I can and if it makes sense.
EDIT:
Solr solution is to slow for Join (Maybe we can try nested). And the current MySQL solution which uses join tables has over 2 billion rows.
so, you just want to store a mapping between User->Cars, and retrieve the cars based on the user...sounds very simple:
Your docs are Users: contain id (indexed), etc fields
one of the field is 'carsliked', multivalued, which contains the set of car ids he likes
you have details about each care in a different collection for example.
given a user id, you retrieve the 'carsliked' field, and get the car details with a cross collection join
You could also use nested object to store each liked car (with all the info about it) inside each user, but is a bit more complex. As a plus, you don't need the join on the query.
Solr would allow you many more things, for example, given a car, which users do like it? Elasticsearch will work exactly the same way (and probably many other tools, given how simple your use case seems).
I have two scenarios that I want to support but I don’t know the best way to design relations in the elasticsearch. I read the entire elasticsearch documentation but I couldn’t find the best way to design types for my scenarios.
Multiple one to many.
Let’s assume that I have the following tables in my relational database that I want to transfer to the elasticsearch:
Transaction table Id User1Id User2Id ….
User table Id Name
Transaction contains two references to User. As far as I know I cannot use the parent->child relation specifying two parents? I need to store transaction and user in separate types because they can be changed separately. I need to be able to search transaction through user details and return users connected with transactions. Any idea how to design such structure in the elastic search?
Many to many
Let’s assume that we have the following tables:
Order Id …
OrderLine OrderId UserId Amount …
User Id Name
Order line is always saved with the order so I thought that I can store order with order lines as a nested object relation but the user must be in the separate table. Is there any way how can I connected multiple users from order line with user type? I assume that I can use application side join but I need to retrieve order and order line always together and be able to search order by user data.
I can use grandparent and grandchildren relations but then I need to make joins in the application. Any idea how to design it in the best way?
Is there a way to add an index to a relationship in an Entity? I can see that attributes can be indexed, but not on relationships.
I have a large dataset and need to check which ones actually have or not a relationship object in a predicate:
[NSPredicate predicateWithFormat:#"relationshipField = nil"]
So I thought that it would be a good idea to index that relationship.
So my question is, can there be ? And if not, is there a performance strategy for this scenario?
You can't do this manually but you don't need to because — empirically speaking — Core Data does it automatically where it can. So that means that 'to one' relationships are automatically given indexes. Check your SQLite store for names like ZENTITY_ZRELATIONSHIP_INDEX to see the proof.
There is no meaningful way to add an index for a 'to many' relationship so Core Data couldn't do that automatically or expose the option. SQLite's format for indices is just a list of rows sorted by the thing being indexed, into which it performs a binary search. It has no way of building such a structure for a multivalued column, and multivalued columns are how Core Data stores to-many links.
Disclaimer: of course, these are all implementation-specific observations that appear in my subjective experience to apply to the current implementation of Core Data. But as a general rule I think you could safely say that Core Data will optimise for relationship lookups as best as it can.