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Merge 'Fix bug: we cant remove order by terms from the head of the list' from Jussi Saurio

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we had an incorrect optimization in `eliminate_orderby_like_groupby()`
where it could remove e.g. the first term of the ORDER BY if it matched
the first GROUP BY term and the result set was naturally ordered by that
term. this is invalid. see e.g.:
```sql
main branch - BAD: removes the `ORDER BY id` term because the results are naturally ordered by id.
However, this results in sorting the entire thing by last name only!

limbo> select id, last_name, count(1) from users GROUP BY 1,2 order by id, last_name desc limit 3;
┌──────┬───────────┬───────────┐
│ id   │ last_name │ count (1) │
├──────┼───────────┼───────────┤
│ 6235 │ Zuniga    │         1 │
├──────┼───────────┼───────────┤
│ 8043 │ Zuniga    │         1 │
├──────┼───────────┼───────────┤
│  944 │ Zimmerman │         1 │
└──────┴───────────┴───────────┘

after fix - GOOD:

limbo> select id, last_name, count(1) from users GROUP BY 1,2 order by id, last_name desc limit 3;
┌────┬───────────┬───────────┐
│ id │ last_name │ count (1) │
├────┼───────────┼───────────┤
│  1 │ Foster    │         1 │
├────┼───────────┼───────────┤
│  2 │ Salazar   │         1 │
├────┼───────────┼───────────┤
│  3 │ Perry     │         1 │
└────┴───────────┴───────────┘

I also refactored sorters to always use the ast `SortOrder` instead of boolean vectors, and use the `compare_immutable()` utility we use inside btrees too.

Closes #1365
This commit is contained in:
Jussi Saurio 2025-05-03 12:48:08 +03:00
commit 306e097950
13 changed files with 98 additions and 176 deletions
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13
core/vdbe/explain.rs
View file

@ -1,3 +1,5 @@
use limbo_sqlite3_parser::ast::SortOrder;
use crate::vdbe::{builder::CursorType, insn::RegisterOrLiteral};
use super::{Insn, InsnReference, OwnedValue, Program};
@ -876,17 +878,10 @@ pub fn insn_to_str(
} => {
let _p4 = String::new();
let to_print: Vec<String> = order
.get_values()
.iter()
.map(|v| match v {
OwnedValue::Integer(i) => {
if *i == 0 {
"B".to_string()
} else {
"-B".to_string()
}
}
_ => unreachable!(),
SortOrder::Asc => "B".to_string(),
SortOrder::Desc => "-B".to_string(),
})
.collect();
(