Fuzz testing is great for finding bugs, but until we fix the bugs,
failing CI runs out of the blue for unrelated PRs is not very
productive. Hopefully we can enable this soon again, but until then,
let's not fail the test suite all the time randomly.
There are two bugs in #1085.
1. `find_free_cell` accesses non-existent free blocks and returns their
size to `allocate_space`. This is out of range access error. The fix is
to add a loop termination condition that stops it when we hit the end of
the blocks
2. This bug is caused by `find_free_cell` some how swallowing the blocks
with size `4 bytes`. So `compute_free_space` consistently undercounts by
`4 bytes`. I've refactored that part of the code to make sure 4 sized
block are not deleted.
I've also added a unit test which proves these fixes work and also added
a function called `debug_print_freelist` which prints all free blocks of
a page.
For now I've silenced the `overflow_page` tests.
Fixes#1085Closes#1111
Previously any block that has a size 4 is deleted resulting in the issue of computed free space
is less than 4 bytes when compared to expected free space.
This PR adds support for `DROP TABLE` and addresses issue
https://github.com/tursodatabase/limbo/issues/894
It depends on https://github.com/tursodatabase/limbo/pull/785 being
merged in because it requires the implementation of `free_page`.
EDIT: The PR above has been merged.
It adds the following:
* an implementation for the `DropTable` AST instruction via a method
called `translate_drop_table`
* a couple of new instructions - `Destroy` and `DropTable`. The former
is to modify physical b-tree pages and the latter is to modify in-memory
structures like the schema hash table.
* `btree_destroy` on `BTreeCursor` to walk the tree of pages for this
table and place it in free list.
* state machine traversal for both `btree_destroy` and
`clear_overflow_pages` to ensure performant, correct code.
* unit & tcl tests
* modifies the `Null` instruction to follow SQLite semantics and accept
a second register. It will set all registers in this range to null. This
is required for `DROP TABLE`.
The screenshots below have a comparison of the bytecodes generated via
SQLite & Limbo.
Limbo has the same instruction set except for the subroutines which
involve opening an ephemeral table, copying over the triggers from the
`sqlite_schema` table and then re-inserting them back into the
`sqlite_schema` table.
This is because `OpenEphemeral` is still a WIP and is being tracked at
https://github.com/tursodatabase/limbo/pull/768
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#897
I don't know when and why we dropped log::* in favor of tracing but when it was done, it made relevant logs not appear any more while debugging so... I added test_log::test which helps by automatically adding info logs from trace package.
this commit introduces the ability of the state machine traversal to handle index interior cell overflow pages. it also makes the state machine states more explicit with match arms.
this commit changes the contents of the state machine state for ClearOverflowPages to contain the BTreeCell instead of the cell index.
this avoids having to repeatedly do an operation to get the BTreeCell from the cell index each time the state is reached
this commit adds the final touches to the state machine for btree_destroy and also introduces a state machine for clear_overflow_pages
this addresses the issue of IO interrupting an operation in progress and solves the following problems:
* performance issues with repeating an operation
* missing page issues with clear overflow pages
modified the btree_destroy subroutine to do an iterative DFS and use the stack cell counters to keep track of whether children have been removed. adds a unit test.
this is the initial commit is for the implementation of DROP TABLE. It adds support for the DROP TABLE instruction and adds a DropBTree instruction. It also implements the btree_drop method in btree.rs which makes use of free_page method which will be implemented via PR https://github.com/tursodatabase/limbo/pull/785
