OnConflict implementation for SQLite provider uses wrong feature of SQLite

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#796 3 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
fsharp, sqlite
Domain
databases

Research direction

The issue names no files or tests; start by locating the SQLite provider's current OnConflict implementation and read the linked SQLite ON CONFLICT and UPSERT documentation. Compare the behavior with other supported providers and the reported NOT NULL case. Done means the chosen SQLite behavior or its documented warning is agreed and implemented, with backward compatibility considered.

Written by the indexing model from the issue text.

Description

sqlite

Describe the bug
I think that implementation of OnConflict uses wrong feature of SQLite.
If you check the SQLite docs mentioned in https://fsprojects.github.io/SQLProvider/core/crud.html#OnConflict you'll see that "ON CONFLICT clause applies to UNIQUE, NOT NULL, CHECK, and PRIMARY KEY constraints".
SQLite has another feature, specifically for UPSERTs - https://sqlite.org/lang_upsert.html . Docs for that feature mention that "UPSERT in SQLite follows the syntax established by PostgreSQL, with generalizations."

I don't know why this feature of SQLite was chosen back in the day. Even though ON CONFLICT was available in SQLite for decades and UPSERT was only added at 2018, when this feature was added to SQLProvider UPSERT had already been available.
Nevertheless, I think it's quite confusing. Behavior of this feature for SQLite is different from other supported providers. I suppose we have two options:

  1. Fix SQLProvider implementation to use proper UPSERTS for SQLite, probably adding a configuration toggle somewhere to enable backward compatibility.
  2. Add a warning to the docs stating that usage of OnConflict feature for SQLite has a broader scope than one could expect.

In my case, I set OnConflict.Ignore to one of my tables, expecting it to only deal with primary key violations.
In the meantime, I had an error in my app, one of the non-null column hasn't been filled, but SQLite hasn't complained about it and just silently refused to insert a row into a table. At the end, by debugging raw sql I was able to figure things out.

Dominant language
F#
Stars
627
Forks
147
Avg merge
2h 2m
Merged PRs (30d)
1

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