Fix the syscall VFS on Linux not to use `PlatformIO`, which is just an
alias for `io_uring`.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1285
WalShared state can be shared without having to wrap everything with a
lock, and instead use atomics on some places and rwlock on others -- for
now.
## Results:
From:
----
Execute `SELECT 1`/limbo_execute_select_1
time: [34.125 ns 34.218 ns 34.324 ns]
Execute `SELECT 1`/sqlite_execute_select_1
time: [28.124 ns 28.254 ns 28.385 ns]
To:
----
Gnuplot not found, using plotters backend
Execute `SELECT 1`/limbo_execute_select_1
time: [31.919 ns 32.113 ns 32.327 ns]
Execute `SELECT 1`/sqlite_execute_select_1
time: [29.662 ns 29.900 ns 30.139 ns]
### The problem:
I often need to copy the output of an `Explain` statement to my
clipboard. Currently this is not possible because it currently will only
write to stdout.
All other limbo output, I am able to run `.output file` in the CLI, then
enter my query and in another tmux pane I simply `cat file | xclip -in
-selection clipboard`.
### The solution:
Expose a `statement.explain()` method that returns the query explanation
as a string. If the user uses something like `execute` instead of
prepare, it will default to `stdout` as expected, but this allows the
user to access the query plan on the prepared statement and do with it
what they please.
Closes#1166
This makes it work like in SQLite where only one schema writer is permitted and readers will return error while preparing statement if the schema is changing.
Beep boop.
What happened you ask? I removed the dumb balancing algorithm I
implemented in favor of SQLite's implementation based on B*Tree[1] where
a page is 2/3 full instead of 1/2. It also tries to balance a page by
taking a maximum 3 pages and distributing cells evenly between them.
I've made some changes that are somewhat related:
* Moved most operations on pages out of BTreeCursor because those
operations are based on a page, not on a cursor, and it makes it easier
to test.
* Fixed `write_u16` and `read_u16` cases that didn't need a implicit
offset calculation. Added: `write_u16_no_offset` and
`read_u16_no_offset` to counter this.
* Added some tests with fuzz testing too.
* Fixed some important actions like: `compute_free_space`,
`defragment_page` and `drop_cell`.
[1] https://dl.acm.org/doi/10.1145/356770.356776Closes#968
We currently have two value types, `Value` and `OwnedValue`. The
original thinking was that `Value` is external type and `OwnedValue` is
internal type. However, this just results in unnecessary transformation
between the types as data crosses the Limbo library boundary.
Let's just follow SQLite here and consolidate on a single value type
(where `sqlite3_value` is just an alias for the internal `Mem` type).
The way this will eventually work is that we can have bunch of
pre-allocated `OwnedValue` objects in `ProgramState` and basically
return a reference to them all the way to the application itself, which
extracts the actual value.
This PR started out as one to improve the API of extensions but I ended
up building on top of this quite a bit and it just kept going. Sorry
this one is so large but there wasn't really a good stopping point, as
it kept leaving stuff in broken states.
**VCreate**: Support for `CREATE VIRTUAL TABLE t USING vtab_module`
**VUpdate**: Support for `INSERT` and `DELETE` methods on virtual
tables.
Sqlite uses `xUpdate` function with the `VUpdate` opcode to handle all
insert/update/delete functionality in virtual tables..
have to just document that:
```
if args[0] == NULL: INSERT args[1] the values in args[2..]
if args[1] == NULL: DELETE args[0]
if args[0] != NULL && len(args) > 2: Update values=args[2..] rowid=args[0]
```
I know I asked @jussisaurio on discord about this already, but it just
sucked so bad that I added some internal translation so we could expose
a [nice API](https://github.com/tursodatabase/limbo/pull/996/files#diff-
3e8f8a660b11786745b48b528222d11671e9f19fa00a032a4eefb5412e8200d1R54) and
handle the logic ourselves while keeping with sqlite's opcodes.
I'll change it back if I have to, I just thought it was genuinely awful
to have to rely on comments to explain all that to extension authors.
The included extension is not meant to be a legitimately useful one, it
is there for testing purposes. I did something similar in #960 using a
test extension, so I figure when they are both merged, I will go back
and combine them into one since you can do many kinds at once, and that
way it will reduce the amount of crates and therefore compile time.
1. Remaining opcodes.
2. `UPDATE` (when we support the syntax)
3. `xConnect` - expose API for a DB connection to a vtab so it can
perform arbitrary queries.
Closes#996
