Currently we have this:
program.alloc_cursor_id(Option<String>, CursorType)`
where the String is the table's name or alias ('users' or 'u' in
the query).
This is problematic because this can happen:
`SELECT * FROM t WHERE EXISTS (SELECT * FROM t)`
There are two cursors, both with identifier 't'. This causes a bug
where the program will use the same cursor for both the main query
and the subquery, since they are keyed by 't'.
Instead introduce `CursorKey`, which is a combination of:
1. `TableInternalId`, and
2. index name (Option<String> -- in case of index cursors.
This should provide key uniqueness for cursors:
`SELECT * FROM t WHERE EXISTS (SELECT * FROM t)`
here the first 't' will have a different `TableInternalId` than the
second `t`, so there is no clash.
1. allow calling op_null with Insn::BeginSubrtn
- BeginSubrtn is identical to Null, but named differently so that
its use in context is clearer
2. Insn::Return: add possibility to fallthrough on non-integer values as
per sqlite spec
Closes#1588
Reviewable commit by commit. CI failures are not related.
Adds support for e.g. `select first_name, sum(distinct age),
count(distinct age), avg(distinct age) from users group by 1`
Implementation details:
- Creates an ephemeral index per distinct aggregate, and jumps over the
accumulation step if a duplicate is found
Closes#1507
This commit adds suport for DROP INDEX.
Bytecode produced by this commit differs from SQLITE's bytecode, main
reason we don't do autovacuum or repacking of pages like SQLITE does.
Closes#1280Closes#1444
This commit adds suport for DROP INDEX.
Bytecode produced by this commit differs from SQLITE's bytecode, main
reason we don't do autovacuum or repacking of pages like SQLITE does.
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
Previously `DELETE FROM ...` only emitted deletes for main table, but
this is incorrect as we want to remove entries from index tables as
well.
Closes#1383
Apply affinities to a range of P2 registers starting with P1.
P4 is a string that is P2 characters long. The N-th character of the string indicates the column affinity that should be used for the N-th memory cell in the range.
If P4==0 then register P3 holds a blob constructed by MakeRecord. If P4>0 then register P3 is the first of P4 registers that form an unpacked record.
Cursor P1 is on an index btree. If the record identified by P3 and P4 is not the prefix of any entry in P1 then a jump is made to P2. If P1 does contain an entry whose prefix matches the P3/P4 record then control falls through to the next instruction and P1 is left pointing at the matching entry.
This operation leaves the cursor in a state where it cannot be advanced in either direction. In other words, the Next and Prev opcodes do not work after this operation.
"Open a new cursor P1 to a transient table. The cursor is always opened read/write even if the main database is read-only. The ephemeral table is deleted automatically when the cursor is closed.
If the cursor P1 is already opened on an ephemeral table, the table is cleared (all content is erased)."
There is still some work to do, but this is a basic setup
Passing 1s and 0s with comments is not rustacean, and since we already follow the pattern of struct flags in other sections of the codebase it's better use it here too.
