Hello,
I need to group a history of operations into buckets, where each bucket should include all operations between a creation and deletion. Currently, I have two separate aggregation pipelines: one for generating the bucket boundaries and another for creating the buckets from those boundaries. I’m using Java to interact with MongoDB.
I’m trying to combine these into a single pipeline. My approach involves using a $lookup after generating the boundaries and calling the $bucket operation within the $lookup pipeline. I’m using $let to inject a variable for accessing the bucket boundaries, but I’m struggling with how to properly inject and set these boundaries.
Regards
Darshan Hiranandani
I’ve attempted to set the boundaries using $wantedBoundaries in various ways, including using $expr, but haven’t been successful. The documentation mentions that $expr is only mandatory for $match.
Could you help clarify whether it’s possible to achieve this within a single pipeline and how to correctly inject the boundaries for the $bucket stage?
Thank you.