Dgraph 21.03.0 is freezing on certain query

Can somebody from the team contact me for bug replication? I don’t want to share our database here in public.

Hi @maaft, Thanks for sharing database. I am able to reproduce it on 21.03 branch.
But on master branch it’s not freezing. I will investigate it see what fixes it on master branch and try to put that fix in 21.03 patch release.

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That would be great, thank you very much!

Hi @JatinDevDG

It seems like that some mutations are the root cause for bringing the database in a state where certain subsequent queries are freezing dgraph.

I have the same problem on latest master. I’ll try to dig deeper and come up with a list of mutations and queries to reproduce this.

Edit: Has dgraph/badger some upper limit for string storage? I discovered that I accidentally saved a 262279 Byte string to some field and after that the database seems to be unstable. If there is some upper/unsafe limit, I think it would be good practice that the GraphQL interface throws an error in that case.

Edit 2: The size of the string does not seem to be the issue here as the the bug occurs also after I fixed it on my side. Will investigate further.

yeah, I guess there is no limit. But I think it got stuck somewhere converting dgraph result to Json.
i will try to investigate it more. If you are able to give more clear reproducible steps on a fresh database then it will be very helpful.

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@maaft , Thanks for reporting this issue. This issue is present in 21.03.0 and has been fixed in 21.03.1 and any later versions. This was introduced in January when the changes related to parsing of DQL result to GraphQL JSON were made.

The issue has been fixed in master with the following PR, Fix(GraphQL): Fix GraphQL encoding in case of empty list by vmrajas · Pull Request #7726 · dgraph-io/dgraph · GitHub .