This format is based on previous discussions:
1. Log header
```rust
/// Log's Header, this will be the 64 bytes in any logical log file.
/// Log header is 64 bytes at maximum, fields added must not exceed that size. If it doesn't exceed
/// it, any bytes missing will be padded with zeroes.
struct LogHeader {
version: u8,
salt: u64,
encrypted: u8, // 0 is no
}
```
2. Transaction format:
* Transaction id
* Checksum u64
* Byte size of all rows combined
* Rows
* End marker (offset position after appending buffer)
3. Row format:
```rust
/// Serialize a row_version into on disk format.
/// Format of a "row" (maybe we could change the name because row is not general enough for
/// future type of values):
///
/// * table_id (root page) -> u64
/// * row type -> u8
///
/// (by row type)
/// Delete:
/// * Payload length -> u64
/// * Rowid -> varint
///
/// Insert:
/// * Payload length -> u64
/// * Data size -> varint
/// * Rowid -> varint
/// * Data -> [u8] (data size length)
fn serialize(&self, buffer: &mut Vec<u8>, row_version: &RowVersion) {
```
Closes#3245
fixes#3231
```zsh
❯ sqlite3
SQLite version 3.50.4 2025-07-30 19:33:53
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> CREATE TABLE t1 (a);
ALTER TABLE t1 ADD COLUMN a;
Parse error: duplicate column name: a
sqlite> ALTER TABLE t1 ADD COLUMN name varchar(255);
SELECT sql FROM sqlite_schema WHERE name = 't1';
CREATE TABLE t1 (a, name varchar(255))
sqlite>
```
```zsh
turso>
turso> CREATE TABLE t1 (a);
ALTER TABLE t1 ADD COLUMN a;
x Parse error: duplicate column name: a
turso> ALTER TABLE t1 ADD COLUMN name varchar(255);
SELECT sql FROM sqlite_schema WHERE name = 't1';
┌─────────────────────────────────────────┐
│ sql │
├─────────────────────────────────────────┤
│ CREATE TABLE t1 (a, name varchar (255)) │
└─────────────────────────────────────────┘
turso>
```
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#3249
Closes#3253
Had to do some slight changes in how we shadow interactions and changed
some of the execution code to accommodate both runtime generation and
pre-run generation (pre-run generation is needed for instance when
running the shrunk plans). This behavior is abstracted by the
`InteractionPlanIterator` trait
Closes#3272
Use SQL over HTTP batch statement in the push logic of sync-engine with
additional condition for `!auto_commit` for every step except from
initial `BEGIN` of txn.
This is needed to avoid non-transactional update if SQLite will decide
to close transaction due to some error and reset state to autocommit
mode.
Closes#3271
This PR implements the `Sequence` and `SequenceTest` opcodes, although
does not yet add plumbing to emit the latter.
SQLite has two distinct mechanisms that determine the final row order
with aggregates:
Traversal order of GROUP BY, and ORDER BY tiebreaking. When ORDER BY
contains only aggregate expressions and/or constants, SQLite has no
extra tiebreak key, but when ORDER BY mixes aggregate and non-aggregate
terms, SQLite adds an implicit, stable row `sequence` so “ties” respect
the input order.
This PR also fixes an issue with a query like the following:
```sql
SELECT u.first_name, COUNT(*) AS c
FROM users u
JOIN orders o ON o.user_id = u.id
GROUP BY u.first_name
ORDER BY c DESC;
```
Because ORDER BY has only an aggregate (COUNT(*) DESC) and no non-
aggregate terms, SQLite traverses the group key (u.first_name) in DESC
order in this case, so ties on c naturally appear with group keys in
descending order.
Previously tursodb would return the group key sorted in ASC order,
because it was used in all cases as the default
Closes#3287
