Apache Flink

hi, team, is there a way to keep data order in keyby operator? for example, if it read data from a S3 file, hope keyby opeartor could keep data order this specific file?

tldr; short answer, no.

When you `keyBy` you are grouping data based on the key and sending to downstream operators. If the parallelism in the downstream operator is >1 you will lose ordering globally (the file in S3), but retain it for each key/group. Retaining order across parallel processes does not scale well.

use event timestamps and watermarks carefully

avoid shuffles and rearrangements rebalance, rescale or broadcast can cause these

parallel to 1 for all stages that need it

use debugging and tracing tools to monitor the ordering. switch this one to have complete observability

use logical event time ordering and watermarks carefully

also consider if absolute ordering is a hard requirement for your solution