We are doing unsafe mut borrowing in `PageContent` currently, and when
new BufferPool is merged, it will be all pointers into an arena anyway.
We just need to be sure to clone the Arc and reference the buffers in
the completion callbacks so they are ensured to live for async IO.
naturally in true spirit of all my previous PR's, I needed to introduce
one while another is open that causes an absurd amount of conflicts.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2456
After #2258, we no longer need to clone/deep copy `PageContent` or
`Buffer`.
We can remove the implementation to make any copying of page data
explicit.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2453
Closes#2440
## Fix 1
Do not start a read transaction when a SELECT is not going to access the
database, which means we can avoid checking whether the schema has
changed.
## Fix 2
Add a field `accesses_db` to `Program` and `Statement` so we can avoid
even checking for `SchemaUpdated` errors when it's not possible to get
one.
## Fix 3
Avoid doing any work in `commit_txn` when not in a transaction. This
optimization is only enabled when `mv_store.is_none()`, because MVCC has
its own logic and this doesn't work with MVCC enabled, and honestly I'm
too tired to find out why. Left an inline comment about it, though.
```sql
Execute `SELECT 1`/limbo_execute_select_1
time: [21.440 ns 21.513 ns 21.586 ns]
change: [-60.766% -60.616% -60.453%] (p = 0.00 < 0.05)
Performance has improved.
```
Effect is even more dramatic in CI where the latency is down over 80%
Closes#2441
In preparation for tracking IO Completions, we need to start to return
IO in places where completions are created. Doing some more plumbing now
to avoid bigger PRs for the future
Closes#2438
## Beef
Adds `AddColumn`, `DropColumn`, `RenameColumn`
## Details
- Previously the test was hardcoded to assume there's always 2 named
columns, so changed a bunch of things for this reason
- Still assumes the primary key column is always `id` and is never
renamed or dropped etc.
Closes#2434
Implement sqlite's fast path defragment algorithm. This path is taken
when:
1. There are 1-2 freeblocks
2. There are at most `max_frag_bytes` fragmented free bytes (-1..=4)
Instead of reconstructing the entire page, it merges the two freeblocks
and then moves the merged freeblock to the left, effectively turning it
into free space in the unallocated region, instead of a freeblock.
`max_frag_bytes` is particularly important when jnserting a new cell,
because if the page contains (in total) ~just enough space for the new
cell, then there can be hardly any fragmented free space because
otherwise, merging the 1-2 freeblocks won't produce enough contiguous
free space to fit the cell.
## Benchmark
```sql
Insert rows in batches/limbo_insert_1_rows
time: [26.692 µs 27.153 µs 27.695 µs]
change: [-9.9033% -2.9097% +1.6336%] (p = 0.55 > 0.05)
No change in performance detected.
Insert rows in batches/limbo_insert_10_rows
time: [38.618 µs 40.022 µs 42.201 µs]
change: [-8.9137% -6.6405% -4.2299%] (p = 0.00 < 0.05)
Performance has improved.
Insert rows in batches/limbo_insert_100_rows
time: [168.94 µs 169.58 µs 170.31 µs]
change: [-22.520% -17.669% -12.790%] (p = 0.00 < 0.05)
Performance has improved.
```
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#2411
This PR integrates virtual tables into the query optimizer. It is a
follow-up to https://github.com/tursodatabase/turso/pull/1727.
The most immediate improvement is better support for inner joins
involving TVFs, particularly when TVF arguments are column references.
### Example
The following two queries are semantically equivalent, but require
different join orders to be valid:
```sql
-- TVF depends on `t.id`, so `t` must be evaluated in outer loop
SELECT t.id, series.value
FROM target t, generate_series(t.id, 3) series;
-- Equivalent query, but with reversed table order in the FROM clause
SELECT t.id, series.value
FROM generate_series(t.id, 3) series, target t;
```
Without optimizer integration, the second query would fail because the
planner would attempt to evaluate `generate_series` before `t`. With
this change, the optimizer detects column dependencies and produces the
correct join order in both cases.
### TODO
Support for outer joins with TVFs is still missing and will be addressed
in a follow-up PR.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2439
The side of the binary expression no longer needs to be stored in
`ConstraintInfo`, since the optimizer now guarantees that it is always
on the right. As a result, only the index of the corresponding constraint
needs to be preserved.
This change extends table-valued function support by allowing arguments
to be column references, not only literals.
Virtual tables can now reject a plan by returning an error from
best_index (e.g., when a TVF argument references a table that appears
later in the join order). The planner using this information excludes
invalid plans during join order search.
