I'm new to graphql, and trying to understand how I might fill this use case.
I have thousands of nodes of a specific type/schema.
Some of these nodes have children, some of them don't.
I'd like to query all the nodes, and return only the ones that don't have children.
This might get more specific in the future, where I'd like to query only nodes that don't have children of a specific type.
Is that even possible?
I've seen plenty of query examples that show how to select children nodes, or nested nodes + fields, or nodes with specific values. It's an easy thing with SQL, I'm just having trouble understanding how it's done with graphql.
Thoughts?
As Daniel Rearden said, there is no built in way in GraphQL to filter or sort the results of a query. We have a few filters in our Gentics Mesh GraphQL API, but it is currently not possible to create a filter involving another list of items (children in your case).
I've added your case to the issue in Github. https://github.com/gentics/mesh/issues/27
Related
In my GraphiQL explorer, it appears that I can query file or allFile, but I don't really understand what the difference between the two is. In fact, every query appears to be "duplicated" in this manner. Can someone explain, or point me to some documentation that explains the difference and when I should use one over the other?
allFile (notice the all prefix) stands for all GraphQL assets of file node type that Gatsby has inferred using the gatsby-source-filesystem, while file is an isolated node that would need to be filtered to get the specific object.
In other words, allFile is exposing all files in your project (at least the ones that Gatsby is aware of), which will give you an array of nodes while file is only pointing to a specific GraphQL node. This single and isolated node normally needs to be filtered to get them among the rest.
The same reasoning applies to allMdx and mdx, allSite and site, etc.
For example, using allMdx example (node created by gatsby-plugin-mdx): let's say you have a blog project where you store your posts in MDX files. In your gatsby-node.js you will query for allMdx node in order to get all posts, then, you will loop through the results and create dynamic pages for each post (using createPage method). In the post template (the template that each specific post will use), instead of querying for allMdx, you will need to use mdx because it's pointing specifically to a single mdx node.
Of course, in your template, you can still use allMdx, for it's not the optimal GraphQL node since you have a specific mdx that will be your single post, filtered by some unique value like the slug, the id, etc.
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'm currently evaluating whether to use elasticsearch or solr in a project and moving through the cases that need to be implemented. I found one case on which I couldn't find any documentation which felt a bit strange to me since the case seemed to be quite common to me. The categories are user supplied so I don't know them in advance. Consider the following part of a taxonomy with documents that can have multiple categories:
Root (3)
Books (2)
Sci-fi (1)
DocumentA
Fantasy (2)
DocumentA
DocumentC
Movies (1)
Action (1)
DocumentB
Games (1)
Adventure
DocumentB
In this case DocumentB could be an entry for e.g. Indiana Jones. Normal term hierarchies can be implemented using the path hierarchy tokenizer in solr/elastic, so DocumentC would have 'Root/Books/Fantasy' as category with a path split on '/'.
DocumentB however would need to have two paths ('Root/Movies/Action' and 'Root/Games/Adventure'). I thought about dynamically adding one category_n field per path for the document in elastic with the path hierarchy tokenizer and then do the category search on all the category_* fields, but i don't know if that would be the right approach, especially considering that the document count for the facets is not simple because the count of a parent node is not the sum of its children (documents can be in multiple child categories and should not be counted more than once).
What would be a good way to implement this in solr/elastic?
Cheers
I ended up using ES and had a category field in which I put every path to the node. So 'Root/Movies/Action' and 'Root/Games/Adventure'. Then I used a path hierarchy tokenizer splitting on / with this field.
ES supports putting multiple paths in that field and searching them. I then used an aggregation with bucketing on the categories, that yielded exactly what I wanted, documents are not counted multiple times if the occure more than one time in a branch.
could you help me with little problem regarding parent-child documents relation?
Considering JSON, I have objects, each of them contains an array of sub-objects. Sub-objects contain some text fields.
I need to maintain full-text-search on these objects and construct snippets. I need highlighting for building snippets.
If I use nested objects, highlighting does not deal with them.
Therefore, I use Parent-Child relationships.
Now I need to retrieve Parent-documents, which children match the query_string. Furthermore, I need to get highlighted fields of matched children and associate each one(each child) with corresponding parent to construct snippets in my application.
Is it possible to accomplish my goal in one query?
I think that you should consider using the children aggregation. With that you can retrieve children items within their parents. It's aggregation so you are not able to get the whole document (just id) but with that you retrieve the relationship... Then with another query you can get document details quickly.
Link here : https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-children-aggregation.html
And more details : https://www.elastic.co/guide/en/elasticsearch/guide/current/children-agg.html
As a part of an Integration Requirement, I need to query Opportunity records that have been Modified after a specific date and time?
Now, Opportunity has a child object called ProductRevenue with a one to many relationship. Is there anyway I can construct a querypage that will fetch records whose Opportunity fields 'OR' its child ProductRevenue's fields have been modified after a specific date and time?
I have tried using the SearchSpec argument, but it does not let me query across child object fields.
For eg:
ObjOpptyQueryPageInput.ListOfOpportunity.Opportunity.searchspec = "([ModifiedDate] > '01/01/2013 00:00:00') OR ([ProductRevenueData.ModifiedDate] >= '01/01/2013 00:00:00')";
[This above code written in C# thew me an error saying - The object Opportunity does not have an integration component called - ProductRevenueData.ModifiedDate.]
Any help will be greatly appreciated. Thank you.
I have been looking for the answer myself, and here is my understanding although not a solution.
In Web Services 2.0, Oracle says "all parent records matching the parent criteria and only children matching the child criteria are returned."
You actually can define "searchspec" on the parent AND the child, and it does work in the way that Oracle defined. However it is probably not the behavior you are looking for. When you do this what happens is you get ALL parents that match the parent.searchspec regardless of whether its child matches the child.searchspec. However those parents will only have the child(ren) that match your child.searchspec in the query result. So if all you wanted was "parents that have these children" or "these children" you are out of luck. Because what you get is "many parents and some of their children."
So even when you are post-processing with two queries you will have to spend some time. :(
By the way your two separate queries will have to look something like this:
query 1.
ObjOpptyQueryPageInput.ListOfOpportunity.Opportunity.searchspec = "([ModifiedDate] > '01/01/2013 00:00:00')";
query 2. ObjOpptyQueryPageInput.ListOfOpportunity.Opportunity.ListOfProductRevenue.ProductRevenue.searchspec = "([ModifiedDate] >= '01/01/2013 00:00:00')";
Then post-process query 2 to take out all parents who have no children.
Then union that with the results from query 1.
From my experience, you will not be able to do this using their V2.0 api (i.e. searchspec). You can perform this using V1.0 api BUT this will return all parent records matching your criteria plus all related ProductRevenue records whether they meet the criteria or not. I do something similar and then post process the data against an xpath predicate filter. The only other option, I think, is 2 separate queries.
I had the same problem, and i tried many ways to resolve the problem, but for now you should deal with the result returned: you can use DOM, XPath or regular expressions to extract the information you want for the returned result.
In my case i used XPath because it's very fast and more easier. This is a link to the question i have posted with the correct answer :
Xpath solution for the parent-child query result
I hope this will fix the problem.