The built-in `unreachable!` macro, believe it or not is just an alias
for `panic!` and does not actually provide the compiler with a hint that
the path is not reachable.
This provides a wrapper around the actual
`std::hint::unreachable_unchecked()`, to be used only in the very hot
path of `execute` where it is not possible to be the incorrect variant.
Closes#2459
SQLite generates those in aggregations like min / max with collation
information either in the table definition or in the column expression.
We currently generate the wrong result here, and properly generating the
bytecode instruction fixes it.
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
Closes#1967
To support this I had to change how we did `epilogue` similarly to how
SQLite does it. SQLIte first declares a `beginWriteOperation` when some
statement is going to necessitate a Write Transaction. And as we now
need to pass the current schema cookie to `epilogue` it was easier to
call epilogue only in one location (like we do with prologue), and just
have each statement declare their intentions separately. This allows us
to not have to pass the Schema around just to do the epilogue. I believe
this is something that @jussisaurio would be interested in.
~Also had to disable the MVCC test, as it was extremely buggy for me.~
Just disabled reprepare statements for MVCC
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2214
Resolves#2378.
```
`ALTER TABLE _ RENAME TO _`/limbo_rename_table/
time: [15.645 ms 15.741 ms 15.850 ms]
Found 12 outliers among 100 measurements (12.00%)
8 (8.00%) high mild
4 (4.00%) high severe
`ALTER TABLE _ RENAME TO _`/sqlite_rename_table/
time: [34.728 ms 35.260 ms 35.955 ms]
Found 15 outliers among 100 measurements (15.00%)
8 (8.00%) high mild
7 (7.00%) high severe
```
<img width="1000" height="199" alt="image" src="https://github.com/user-
attachments/assets/ad943355-b57d-43d9-8a84-850461b8af41" />
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2399
This will save some work when yielding to IO. Previously, on every
invocation, if the record was a packed record, we parsed it and iterated
through the values to check for nulls. Now, the pre-seeking work is done
only once.
Reviewed-by: Preston Thorpe <preston@turso.tech>
Closes#2394
We need to load rowids into mvcc's store in order before doing any read
in case there are rows.
This has a performance penalty for now as expected because we should,
ideally, scan for row ids lazily instead.
Merge 'IN queries' from Glauber Costa
Implement IN queries.
It is currently as todo!(), but my main motivation is that scavenging
for EXPLAINs, that pattern, at least in simple queries like SELECT ...
IN (1,2,3) uses the AddImm instruction we just added.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2342
This PR introduces two methods to pager. Very much inspired by
`with_schema` and `with_schema_mut`. `Pager::with_header` and
`Pager::with_header_mut` will give to the closure a shared and unique
reference respectively that are transmuted references from the `PageRef`
buffer.
This PR also adds type-safe wrappers for `Version`, `PageSize`,
`CacheSize` and `TextEncoding`, as they have special in-memory
representations.
Writing the `DatabaseHeader` is just a single `memcpy` now.
```rs
pub fn write_database_header(&self, header: &DatabaseHeader) {
let buf = self.as_ptr();
buf[0..DatabaseHeader::SIZE].copy_from_slice(bytemuck::bytes_of(header));
}
```
`HeaderRef` and `HeaderRefMut` are used in the `with_header*` methods,
but also can be used on its own when there are multiple reads and writes
to the header, where putting everything in a closure would add too much
nesting.
Reviewed-by: Preston Thorpe (@PThorpe92)
Closes#2234
Our compat matrix mentions a couple of opcodes: ToInt, ToBlob, etc.
Those opcodes do not exist.
Instead, there is a single Cast opcode, that takes the affinity as a
parameter.
Currently we just call a function when we need to cast. This PR fixes
the compat file, implements the cast opcode, and in at least one
instance, when explicitly using the CAST keyword, uses that opcode
instead of a function in the generated bytecode.
Reviewed-by: Preston Thorpe (@PThorpe92)
Reviewed-by: Preston Thorpe (@PThorpe92)
Closes#2352
Our compat matrix mentions a couple of opcodes: ToInt, ToBlob, etc.
Those opcodes do not exist.
Instead, there is a single Cast opcode, that takes the affinity as a
parameter.
Currently we just call a function when we need to cast. This PR fixes
the compat file, implements the cast opcode, and in at least one
instance, when explicitly using the CAST keyword, uses that opcode
instead of a function in the generated bytecode.
closes: #2101
Refactors exec_concat_ws to skip null and blob arguments instead of
inserting separators for them. Also adds a fuzz test.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2338
closes#1893
Adds some fairly extensive tests but I'll continue to add some python
tests on top of the unit tests.
## Restart:
tested ✅
- open new DB
- create table and do a bunch of inserts
- `pragma wal_checkpoint(RESTART);`
- close db file
- re-open and verify we can read the wal/repopulate the frame cache
- verify min|max frame
tested ✅
- open same DB
- add more inserts
- `pragma wal_checkpoint(RESTART);`
- do _more_ inserts
- close
- re-open
- verify checksums/max_frame are valid
- verify row count
## Truncate
tested ✅
- open new db
- create table and add inserts
- `pragma wal_checkpoint(truncate);`
- close file
- verify WAL file is empty (32 bytes, header only)
- re-open file
- verify content/row count
tested ✅
- open db
- create table and insert many rows
- `pragma wal_checkpoint(truncate);`
- insert _more_ rows
- close db file
- verify WAL file is valid
- re-open file
- verify we can read entire file/repopulate the frame cache
<img width="541" height="315" alt="image" src="https://github.com/user-
attachments/assets/0470c795-5116-4866-b913-78c07b06b68c" />
```
# header
magic=0x377f0682
version=3007000
page_size=4096
seq=2
salt=ec475ff2-7ea94342
checksum=c9464aff-c571cc22
```
Closes#2179
