Presently documented behavior was effected for the 3.35.0 release of 2021-03-12, which was awhile after version 3.31.1 <u>[was released](https://sqlite.org/chronology.html)</u>. The [3.35.0 release notes](https://sqlite.org/releaselog/3_35_0.html) mention "Generalize UPSERT" at item 3. I can attest that version 3.35.0 behaves as you <b>Expected</b>, having observed that personally using your input. Unfortunately, short of using the documentation repository and rebuilding the docs for past versions, there is not a convenient way to see how past SQLite versions conform to <i>present</i> documentation. (Added via edit:) BTW, thanks for your nicely done bug report. Even though this is not technically a bug (vis-à-vis doc/code tracking), we appreciate well-explained bug reports with repro steps, and observed/expected results.