I'm performing a multimatch search against an ElasticSearch index, and I want to get back the source object with fields in the same order as they were stored in.
However, when I get the response back from the ElasticSearch query, the fields are in alphabetical order (which is not particularly useful for what I'm doing). I'm fairly confident that it used to behave the desired way in a previous version of ES, but since I upgraded recently it is only returning the fields in alphabetical order.
Edit: Note that if I perform a standard match_all search, then I do get the fields back in the original order. I wonder if it has something to do with the multimatch query?
Edit 2: OK, I just ran it again and it returned the fields in a random order (not alphabetical). Maybe this is a bug in ElasticSearch?
You cannot guarantee any order in what is returned. The source document is a plain old JSON object and by definition:
An object is an unordered set of name/value pairs.
Related
I'm using Solr to run a query on one of our cores. Suppose my documents have two fields: ID, and Name. I also have a separate list of IDs I'm grabbing from a database and passing into the query to boost certain results.
If the document gets returned in the query and the ID is in the list it goes to the top of the results, and if it gets returned in the query and the ID is not in the list then it goes below those that are in the list. The former is from the "boost". My query is something like this -
http://mysolrserver:8983/solr/MyCore/MyQueryHandler?q=Smith&start=0&rows=25&bq=Id%3a(36+OR+76+OR+90+OR+224+OR+391)
I am able to get the boost query working but I need the boosted results to be in alphabetical order by name, then the non boosted results under that also in alphabetical order by name. I need to know what to user for the &sort= parameter.
&sort=score%20desc,Name+asc does not work.
I've looked over a lot of documentation, but I still don't know if this even possible. Any help is appreciated. Thanks!
Solr version is 6.0.1. I am actually using SolrNet to interface with Solr, but I think I can figure out the SolrNet part if I know what the url's &sort= parameter value needs to be.
I figured it out, by doing away with the boost query. I added a sort query using the "exists" function and passing it a sub-query for the ID. The exists returns a boolean value to sort on, then I added the name as a second sort. It works perfect!!
The URL looks like this:
http://mysolrserver:8983/solr/MyCore/MyQueryHandler?q=Smith&start=0&rows=25&sort=exists(query({!v=%27Id:(36+OR+76+OR+90+OR+224+OR+391)%27}))%20DESC,%20Name%20ASC
The closest match to your requirement is the query elevation component[1] .
In your particular case I would first sort my Ids according to my requirements ( sorting them by name for example), then maintain them in the elevate.xml.
At query time you can use the "forceElevation" parameter to force the elevation and then sort the remaining results by name.
[1] https://cwiki.apache.org/confluence/display/solr/The+Query+Elevation+Component
We have a simple web page, where the user can provide some input and query the database. We currently use mongodb but want to migrate to elasticsearch, since the queries are faster.
There are some required search fields, like start and end date, and some optional ones, like a search string to match an entry, or a parent search string, to match parent entries. Parent-child relations are just described through fields containing each entry's ancestors ids.
The question is the following: If both search and parent search string are provided, is there a way to know before executing the queries, which query should be executed first, in order to provide results faster and to be more performant?
For example, it could be that a specific parent search results in only 2 docs/parent entries, and then we can fetch all children matching the search string. In that case we should execute firstly the parent query and then the entry query.
One option would be to get the count of both queries and then execute first the one with the smallest count, but isn't this solution worse, since the queries are going to be executed twice? Once for the count and once for the actual query.
Are there any other options to solve this?
PS. We use elasticsearch v1.7
Example
Let's say the user wants to search for all entries matching the following fields.
searchString: type:BLOCK AND name:test
parentSearchString: name:parentTest AND NOT type:BLOCK
This means that we either have to
fetch all entries (parents) matching the parentSearchString and store their ids. Then, we have to fetch all entries that match the searchString and also have to contain any of the parent ids in the ancestors field.
OR
fetch all entries that match the searchString and store all ancestors ids. Then fetch all entries that match the parentSearchString and their id is one of the ancestors ids.
Just to clarify, both parent and children entries have the exact same structure and reside in the same index. We cannot have different indices since the pare-child relation can be 10 times nested, so an entry can be both a parent and a child. An entry looks more or less like:
{
id: "e32452365321",
name: "name",
type: "type",
ancestors: "id1 id2 id3" // stored in node as an array of ids
}
First of all, I would advise you, to upgrade your Elasticsearch version, if possible. There happened a lot since 1.7 and to be honest, I can't tell if all of what's written in the following article is valid for such an old version (probably it isn't).
But to your actual question: Hopefully I am understanding you correctly, but you try to estimate how costly a query for Elasticsearch is? Well, you don't have to. If you provide all 'queries' in one nested query, Elasticsearch will do that for you: https://www.elastic.co/blog/elasticsearch-query-execution-order
Regarding speed, there is one other thing I can mention: calculating score does take time. So if sorting is not based on the elasticsearch _score, you want to use boolean filter queries. This would also apply, if you want to sort only by _score of parent matches, then you could put the query for children into a filter.
update
Thanks to your example, I now see the problem. Self referencial Parent-Child relations are unfortunately not supported by ElasticSearch, so your approach is probably right. You might want to check out the short chapter of the documentation about application-joins.
So yes, in general, you want to send the second query with the least possible amount of ids/terms. While getting counts for both queries is not as bad as you might think, because the results are most likely still cached, does it actually help? Because if you're going from child to parent, you would have to count the ancestors (field values), and not the actual document count.
I would argue, that the most expensive operation is very often fetching result source from disk. So whichever way you go, you probably should only fetch what you need in the first query. So your options are:
Fetch only the id of parent matches, and then use a terms filter on ancestors in the second query.
Or, fetch only the ancestors field of child matches, and use an id filter in your second query.
Unfortunately, I can't help you more than that, since I don't have enough experience in comparing speed of those approaches. My guess would be, that an id filter might be faster in general. But that's just a guess...
I want to have in the search response only documents with specified doc id. In stackoverflow I found this question (Lucene filter with docIds) but as far as I understand there is created the additional field in the document and then doing search by this field. Is there another way to deal with it?
Lucene's docids are intended only to be internal keys. You should not be using them as search keys, or storing them for later use. Those ids are subject to change without warning. They will be changed when updating or reindexing documents, and can change at other times, such as segment merges, as well.
If you want your documents to have a unique identifier, you should generate that key separate from the docId, and index it as a field in your document.
I can't find any informations on Azure Search documentation about how the results are sorted when the query sent is empty. I've also read the Empty Search section of ElasticSearch but still can't find any answer.
Is this sorting by Key?
Is the backend sending a batch of parallel requests and concatenate the results since the sorting doesn't matter?
in case of empty query, the sort order is unspecified. You cannot rely on any particular order. If you need a specific order, ask for it using orderby query parameter.
HTH,
Eugene
I've got an Entity model (in Mongoid) that I'm trying to search on its keywords field which is an array. I want to do a query where I pass in an array of potential search terms, and any entity that matches any of the terms will pass.
I don't have this working well yet.
But, why I'm asking this question, is that it's more complex. I also DONT want to return any entities that have been marked as "do not return" which I do via a "ignore_project_ids" parameter.
So, when I query, I get 0 results. I was using Bonsai.io. But, I've moved this to my own EC2 instance to reduce complexity/variables on solving the problem.
So, what am I doing wrong? Here are the relevant bits of code.
https://gist.github.com/3405763
You want a terms query rather than a term query - a term query is only interested in equality, whereas a terms query requires that the field match any of the specified values.
Given that you don't seem to care about the query score (you're sorting by another attribute), you'll get faster queries by using a filtered query and expressing your conditions as filters