We recently published a comparison of learned indexes (including RadixSpline and the PGM index posted yesterday)in VLDB: <a href="https://vldb.org/pvldb/vol14/p1-marcus.pdf" rel="nofollow">https://vldb.org/pvldb/vol14/p1-marcus.pdf</a>
Talk on YouTube:<p><a href="https://www.youtube.com/watch?v=or0JXc4UQ-4" rel="nofollow">https://www.youtube.com/watch?v=or0JXc4UQ-4</a>