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0c9216d1cc
This PR emit CDC entries as changes in `sqlite_schema` table for DDL
statements: `CREATE TABLE` / `CREATE INDEX` / etc.
The logic is a bit tricky as under the hood `turso` can do some implicit
DDL operations like:
1. Creating auto-indexes in case of `CREATE TABLE`
2. Deletion of all attached indices in case of `DROP TABLE`
```
turso> PRAGMA unstable_capture_data_changes_conn('full');
turso> CREATE TABLE t(x, y, z UNIQUE, q, PRIMARY KEY (x, y));
turso> CREATE INDEX t_xy ON t(x, y);
turso> CREATE TABLE q(a, b, c);
turso> ALTER TABLE q DROP COLUMN b;
turso> SELECT
change_id,
id,
change_type,
table_name,
bin_record_json_object(table_columns_json_array(table_name), before) AS before,
bin_record_json_object(table_columns_json_array(table_name), after) AS after
FROM turso_cdc;
┌───────────┬────┬─────────────┬───────────────┬─────────────────────────────────────────────────────────────────────┬─────────────────────────────────────────────────────────────────────┐
│ change_id │ id │ change_type │ table_name │ before │ after │
├───────────┼────┼─────────────┼───────────────┼─────────────────────────────────────────────────────────────────────┼─────────────────────────────────────────────────────────────────────┤
│ 1 │ 2 │ 1 │ sqlite_schema │ │ {"type":"table","name":"t","tbl_name":"t","rootpage":3,"sql":"CREA… │
├───────────┼────┼─────────────┼───────────────┼─────────────────────────────────────────────────────────────────────┼─────────────────────────────────────────────────────────────────────┤
│ 2 │ 5 │ 1 │ sqlite_schema │ │ {"type":"index","name":"t_xy","tbl_name":"t","rootpage":6,"sql":"C… │
├───────────┼────┼─────────────┼───────────────┼─────────────────────────────────────────────────────────────────────┼─────────────────────────────────────────────────────────────────────┤
│ 3 │ 6 │ 1 │ sqlite_schema │ │ {"type":"table","name":"q","tbl_name":"q","rootpage":7,"sql":"CREA… │
├───────────┼────┼─────────────┼───────────────┼─────────────────────────────────────────────────────────────────────┼─────────────────────────────────────────────────────────────────────┤
│ 4 │ 6 │ 0 │ sqlite_schema │ {"type":"table","name":"q","tbl_name":"q","rootpage":7,"sql":"CREA… │ {"type":"table","name":"q","tbl_name":"q","rootpage":7,"sql":"CREA… │
└───────────┴────┴─────────────┴───────────────┴─────────────────────────────────────────────────────────────────────┴─────────────────────────────────────────────────────────────────────┘
```
For now, CDC capture only all explicit operations and ignore all
implicit operations. The reasoning for that is that one use case for CDC
is to apply logical changes as is with simple SQL statements - but if
implicit operations will be logged to the CDC table too - we can have
hard times using simple SQL statement (for example, creation of
`autoindices` will always work; implicit deletion of indices for `DROP
TABLE` also can lead to some troubles and force us to is `DROP INDEX IF
EXISTS ...` statements + we will need to filter out autoindices in this
case too).
Also, to simplify PR, for now `DatabaseTape` from `turso-sync` package
just ignore all schema changes from CDC table.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes #2426
Integration and regression test suite.
# run all tests
cargo test
# run individual test
cargo test test_sequential_write -- --nocapture