# Very simple filter matches real objects but incremental matches aren't delivered via Kafka

**URL:** <https://www.rubin.community/t/very-simple-filter-matches-real-objects-but-incremental-matches-arent-delivered-via-kafka/12277>\
**Category:** Lasair\
**Created:** [July 10, 2026, 5:10pm UTC](https://www.rubin.community/t/very-simple-filter-matches-real-objects-but-incremental-matches-arent-delivered-via-kafka/12277 "2026-07-10T17:10:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![GiordanoBruno](https://avatars.discourse-cdn.com/v4/letter/g/dc4da7/32.png) [@GiordanoBruno](https://www.rubin.community/u/GiordanoBruno)\
**Post date:** [July 10, 2026, 5:10pm UTC](https://www.rubin.community/t/very-simple-filter-matches-real-objects-but-incremental-matches-arent-delivered-via-kafka/12277/1 "2026-07-10T17:10:42Z")

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Hello, please find below a description of an issue I am facing with my alert consumer on a very simple filter :

Distribution: Kafka stream, with lite lightcurve  
WHERE: objects.nDiaSources \> 1 AND (sherlock\_classifications.classification != ‘VS’ OR sherlock\_classifications.classification IS NULL)  
Tables joined: objects, sherlock\_classifications, crossmatch\_tns

The filter is actively matching real, fresh DiaObjects (confirmed via the /api/query/ REST endpoint), but those matches are not being published to the filter’s Kafka topic. Only a static, unchanging batch of ~10 recycled example objects ever arrives on the topic, delivered once whenever the filter is re-saved in the web UI but never as new matches occur.

Is there a known issue where a filter’s live/incremental Kafka delivery stops working (while the filter’s match query itself keeps working, and the one-time save-triggered test push keeps working)? Is there anything filter-side (e.g. re-activating the filter, a distribution-settings toggle, or the join across objects/sherlock\_classifications/crossmatch\_tns) that could cause this?

Happy to provide the filter ID/account details via a non-public channel if useful for debugging.

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**Author:** ![roy](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/roy/32/1254_2.png) [@roy](https://www.rubin.community/u/roy)\
**Post date:** [July 11, 2026, 10:12am UTC](https://www.rubin.community/t/very-simple-filter-matches-real-objects-but-incremental-matches-arent-delivered-via-kafka/12277/2 "2026-07-11T10:12:18Z")

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Hi Bruno  
I made a [copy based on your post above](https://lasair.lsst.ac.uk/filters/1194/run/), and there are 1000’s of results. I set it to “Trigger on new alert” and “Kafka Lite Lightcurve”. Maybe we can both watch the Kafka topic `lasair_1BrunoFilter` over the next days, and see if the stream is as it should be.  
Roy

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**Author:** ![roy](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/roy/32/1254_2.png) [@roy](https://www.rubin.community/u/roy)\
**Post date:** [July 12, 2026, 8:00am UTC](https://www.rubin.community/t/very-simple-filter-matches-real-objects-but-incremental-matches-arent-delivered-via-kafka/12277/3 "2026-07-12T08:00:21Z")

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Got a lot of Kafka last night, so I’ll close this issue. If you are still having trouble, please contact me directly.