[Bug][mongo] rewriteOutputBuffer should emit +I rather than +U

[loserwang1024]

Search before asking

• I searched in the issues and found nothing similar.

Flink version

1.18

Flink CDC version

2.4.2

Database and its version

Whatever

Minimal reproduce step

Reason

Snapshot split read will read snapshot data, and then backfill log between (low_watermark, high_watermark). The whole read is seen as the snapshot image at high_watermark, which is all +I records to downstream。

However, rewriteOutputBuffer method replace record here but not change the type to +I。

Minimal reproduce step

Update or Replace value during [snapshot, highwatermark), for example:
test,
here I want to get "+I[2000, user_21, Pittsburgh, 123567891234]", rather return +U[2000, user_21, Pittsburgh, 123567891234]

What did you expect to see?

get "+I[2000, user_21, Pittsburgh, 123567891234]"

What did you see instead?

return +U[2000, user_21, Pittsburgh, 123567891234]

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!