`balance_non_root` should be as close as possible to `balance_non_root`
in SQLite. This commits extract `balance_non_root` from `balance` and
renames `balance_leaf` to `balance` as it enables future work on a
complete `balance_non_root` procedure.
This PR's genesis is from investigating #532, but I still can't reliably
reproduce it on either `main` or this branch so I don't know if this PR
_fixes_ anything, but I guess it aligns us more with sqlite anyway
---
Anyway: I looked at DBs created with limbo and with sqlite using
[ImHex](https://github.com/WerWolv/ImHex) and the differences seem to
be:
1. SQLite uses varint according to [the
spec](https://www.sqlite.org/fileformat.html#record_format), whereas
limbo always encodes integers as i64
2. Limbo adds 4 bytes of zeros for overflow page pointer (even in cases
where the cell doesnt overflow)
3. Limbo adds a space after `CREATE TABLE name` before the `(` even when
user doesn't specify it?
I implemented the following:
- Fix 1: Varint serialization of i8, i16, i24, i32, i48 and i64
according to payload, instead of always using i64
- Fix 2: Removed the 4 bytes reserved for overflow page pointer in non-
overflow cases
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#550
small follow up to https://github.com/tursodatabase/limbo/pull/539
contains:
- Variable renaming and comments to `btreecursor.insert_into_cell()`
- New utility methods `pagecontent.header_size()`,
`pagecontent.cell_pointer_array_size()`,
`pagecontent.unallocated_region_start()` and
`pagecontent.unallocated_region_size()`
- Refactor of `btreecursor.compute_free_space()` (plus comments and
variable renaming)
- Rename `pagecontent.cell_get_raw_pointer_region()` to
`pagecontent.cell_pointer_array_offset_and_size()` and remove its usage
in `btreecursor.defragment_page()`
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#543
Implements [json_array](https://sqlite.org/json1.html#jarray).
As a side quest, this PR also fixes an issue with the `CHAR` function
which didn't work properly if the parameters were non-leaf AST nodes.
The PR is quite big, because as I mentioned in https://github.com/tursod
atabase/limbo/issues/127#issuecomment-2541307979 we had to modify
`OwnedValue::Text` to support a `subtype` parameter, which is what
SQLite does.
Closes#504
Since page cache is now shared by default, we need to cache pages by
page number and something else. I chose to go with max_frame of
connection, because this connection will have a max_frame set until from
the start of a transaction until the end of it.
With key pairs of (pgno, max_frame) we make sure each connection is
caching based on the snapshot it is at as two different connections
might have the same pageno being using but a different frame. If both
have same max_frame then they will share same page.
Closes#468
Since page cache is now shared by default, we need to cache pages by
page number and something else. I chose to go with max_frame of
connection, because this connection will have a max_frame set until from
the start of a transaction until the end of it.
With key pairs of (pgno, max_frame) we make sure each connection is
caching based on the snapshot it is at as two different connections
might have the same pageno being using but a different frame. If both
have same max_frame then they will share same page.
This includes an inner struct in Page wrapped with Unsafe cell to access
it. This is done intentionally because concurrency control of pages is
handled by pages and not by the page itself.
Since we expect to ensure thread safety between multiple threads in the
future, we extract what is important to be shared between multiple
connections with regards to WAL.
This is WIP so I just put whatever feels like important behind a RwLock
but expect this to change to Atomics in the future as needed. Maybe even
these locks might disappear because they will be better served with
transaction locks.
- Changed `Cursor` trait to be able to get access to `root_page`
- SQLite only updates last_insert_rowid for non-schema inserts. So we check if the `InsertAwait` is not for `root_page` before
updating rowid
