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.
modified the Null instruction to more closely match SQLite semantics. Allows passing in a second register and all registers from r1..r2 area set to null
the command for drop table translation has been updated so that it more closely matches the semantics of SQLite's drop table command.
there are a few more things missing like ephemeral tables, destroy etc.
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
This is a first step to supporting [sqlite column
affinity](https://www.sqlite.org/datatype3.html) properly in limbo --
just adds an `affinity()` function to `Column` that can then be used
elsewhere
Closes#1030
Fix#1012
In the INSERT statement generated by dump function, if the type affinity
of the value is TEXT, replace each single quotation mark with two single
quotation marks, and wrap it with single quotation marks.
Example:
```plaintext
limbo> CREATE TABLE users (id INT PRIMARY KEY, name VARCHAR(100));
INSERT INTO users (id, name) VALUES
(1, 'Alice'),
(2, 'Bob'),
(3, 'Char''lie');
SELECT * FROM users;
1|Alice
2|Bob
3|Char'lie
limbo> .dump
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE users (id INT PRIMARY KEY, name VARCHAR (100));
INSERT INTO users VALUES(1,'Alice');
INSERT INTO users VALUES(2,'Bob');
INSERT INTO users VALUES(3,'Char''lie');
COMMIT;
```
Closes#1034
In the INSERT statement generated by dump function, if the type affinity
of the value is TEXT, replace each single quotation mark with two single
quotation marks, and wrap it with single quotation marks.
This PR is extracted from the sqlite fuzzing exploration effort in
https://github.com/tursodatabase/limbo/pull/1021
---
We were not evaluating constant conditions (e.g '1 IS NULL') when there
were no tables referenced in the query, because our WHERE term
evaluation was based on "during which loop" to evaluate them. However,
when there are no tables, there are no loops, so they were never
evaluated.
Closes#1023
When testing with `test-shell` the test may error and the error file
will be tracked in git. Added gitignore rule to always not track
`limbo_output.txt`
Closes#1027
