enso/distribution/lib/Standard/Base
GregoryTravis 8260a9587f
Column-level lexically-scoped CTE expressions (#10826)
This implements `DB_Column.with`, which uses `WITH ... AS` SQL clauses to remove duplicates in the generated SQL.

After a discussion with @radeusgd, we concluded that we will probably want a more complete CTE implementation, so this one is useful for now to deal with big queries (like `round`).

# Important Notes
Still to do in this PR:

- [x] Rename `with` to `let` (or something similar)
- [x] tests
- [x] documentation
- [x] remove `State` hack by moving query generation into a class and using a `Ref` field for scoping

Results on `round_float`:

| --- | SQL length in characters (unprettified) | SQL length in lines (prettified) |
| --- | --- | --- |
| Without CTEs | 13193 | 851 |
| With CTEs | 3644 | 187 |

Compare the SQL:

[without-ctes.sql.txt](https://github.com/user-attachments/files/16629356/without-ctes.sql.txt)
[with-ctes.sql.txt](https://github.com/user-attachments/files/16629357/with-ctes.sql.txt)

Update, with name shortening:

| --- | SQL length in characters (unprettified) | SQL length in lines (prettified) |
| --- | --- | --- |
| Without CTEs | 13193 | 853 |
| With CTEs | 2427 | 176 |

[without-cte.txt](https://github.com/user-attachments/files/16694328/without-cte.txt)
[with-cte.txt](https://github.com/user-attachments/files/16694327/with-cte.txt)
2024-08-28 18:23:51 +00:00
..
0.0.0-dev Column-level lexically-scoped CTE expressions (#10826) 2024-08-28 18:23:51 +00:00