Add implementation of returnable last_seq - #800
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veronika-alraheem wants to merge 1 commit into
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ricellis
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Aug 28, 2026
| if entry.entryType == seqEntryRow { | ||
| break | ||
| } | ||
| result = *entry.seq |
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I think this should be defensive with the != nil check in the same way as in the following else if.
I think the only way it could be nil is if a page was returned with a nil last_seq - I don't think that is very likely, but I'd rather not find via the nil de-reference panic if it ever does happen.
In the case that it did we should probably just skip it, so that we can return the furthest possible (if there are pages with non-null last_seq available) or the previous result that was the furthest one we reached before finding the nil.
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PR summary
Add implementation of returnable last_seq for safe checkpoint management.
Fixes: i1284
PR Checklist
Please make sure that your PR fulfills the following requirements:
Angular Commit Message Guidelines.
PR Type
What is the current behavior?
The
ChangesFollowerAPI streams changes as individualChangesResultItemobjects but provides no mechanism for users to determine a safe sequence ID to use as a checkpoint. For heavily filtered feeds where pages return empty results, users have no way to advance their checkpoint even though the feed has progressed internally.What is the new behavior?
A new public method
getLastSeqNewerThan(lastPersistedSeqId)is added toChangesFollower. After fully processing aChangesResultItem, users can call this method with the item's seq value to obtain the most recent sequence ID that is safe to persist as a checkpoint.The method advances past any empty pages (e.g. from heavily filtered feeds) that the follower has seen since the given sequence ID, returning the furthest safe checkpoint available at that point.
Does this PR introduce a breaking change?