Summarising from other places.
- Storing explicit values – like
:missing or nil – for potentially missing fields leads to faster queries when you are interested in absence of data.
- Empty vectors will be treated as missing in queries – they are not indexed.
- Examples of ‘absence queries’ when fields are missing: 1, 2.
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Jeremy’s idea of using get-attr. I did a benchmark of various query strategies, which seems to show – for that particular data example – that the idea performs well.
Jeremy added more nuance:
IIRC the real performance challenges arise when joining in the presence of multiple potential absences (at least)
(Deleted the previous post in favour of this, hopefully, clearer one.)