# Fix: Clean up DBSP state table when dropping materialized views
## Problem
When dropping a materialized view, the internal DBSP state table (e.g.,
`__turso_internal_dbsp_state_v1_view_name`) and its automatic primary
key index were not being properly cleaned up. This caused two issues:
1. **Persistent schema entries**: The DBSP table and index entries
remained in `sqlite_schema` after dropping the view
2. **In-memory schema inconsistency**: The DBSP table remained in the
in-memory schema's `tables` HashMap, causing "table already exists"
errors when trying to recreate a materialized view with the same name
## Root Cause
The issue had two parts:
1. **Missing sqlite_schema cleanup**: The `translate_drop_view` function
deleted the view entry from `sqlite_schema` but didn't delete the
associated DBSP state table and index entries
2. **Missing in-memory schema cleanup**: The `remove_view` function
removed the materialized view from the in-memory schema but didn't
remove the DBSP state table and its indexes
## Solution
### Changes in `core/translate/view.rs`
- Added a second pass loop in `translate_drop_view` to scan
`sqlite_schema` and delete DBSP table and index entries
- The loop checks for entries matching the DBSP table name pattern
(`__turso_internal_dbsp_state_v{version}_{view_name}`) and the automatic
index name pattern (`sqlite_autoindex___turso_internal_dbsp_state_v{vers
ion}_{view_name}_1`)
- Registers for comparison values are allocated outside the loop for
efficiency
- Column registers are reused across loop iterations
### Changes in `core/schema.rs`
- Updated `remove_view` to also remove the DBSP state table and its
indexes from the in-memory schema's `tables` HashMap and `indexes`
collection
- This ensures consistency between the persistent schema
(`sqlite_schema`) and the in-memory schema
### Tests Added
Added two new test cases in `testing/materialized_views.test`:
1. **`matview-drop-cleans-up-dbsp-table`**: Explicitly verifies that
after dropping a materialized view:
- The view entry is removed from `sqlite_schema`
- The DBSP state table entry is removed from `sqlite_schema`
- The DBSP state index entry is removed from `sqlite_schema`
2. **`matview-recreate-after-drop`**: Verifies that a materialized view
can be successfully recreated after being dropped, which implicitly
tests that all underlying resources (including DBSP tables) are properly
cleaned up
## Testing
- All existing materialized view tests pass
- New tests specifically verify the cleanup behavior
- Manual testing confirms that materialized views can be dropped and
recreated without errors
## Related
This fix ensures that materialized views can be safely dropped and
recreated, resolving issues where the DBSP state table would persist and
cause conflicts.
Reviewed-by: Preston Thorpe <preston@turso.tech>
Closes#3928
Depends on #3920
Moves some code around so it is easier to reuse and less cluttered in
`execute.rs`, and changes how `compare` works. Instead of mutating some
register, we now just return the possible `ValueRef` representation of
that affinity. This allows other parts of the codebase to reuse this
logic without needing to have an owned `Value` or a `&mut Register`
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#3923
Depends on #3919
Also change `op_compare` to reuse the same compare_immutable logic
First step to finish #2304
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#3920
MVCC is like the annoying younger cousin (I know because I was him) that
needs to be treated differently. MVCC requires us to use root_pages that
might not be allocated yet, and the plan is to use negative root_pages
for that case. Therefore, we need i64 in order to fit this change.
Improve serialization for DBSP views.
The serialization code was written organically, without much forward
thinking about stability as we evolved the table and operator format.
Now that this is done, we are at at point where we can actually make it
suck less and take a considerable step towards making this production
ready.
We also add a simple version check (in the table name, because that is
much easier than reading contents in parse_schema_row) to prevent views
to be used if we had to do anything to evolve the format of the circuit
(including the operators)
Closes#3351
