Delete data from synced -> local

Author: simolus3

crates/core/src/schema/management.rs

@@ -39,25 +39,16 @@ fn update_tables(db: *mut sqlite::sqlite3, schema: &Schema) -> Result<(), PowerS
         // In a block so that all statements are finalized before dropping tables.
         for table in &schema.tables {
             if let Some(existing) = existing_tables.remove(&*table.name) {
-                if existing.local_only && !table.local_only() {
-                    // Migrate from a local-only to a synced table. Because none of the local writes
-                    // would have created CRUD entries, we'll have to re-create the table from
-                    // scratch.
+                if existing.local_only != table.local_only() {
+                    // Migrating between local-only and synced tables. This works by deleting
+                    // existing and re-creating the table from scratch. We can re-create first and
+                    // delete the old table afterwards because they have a different name
+                    // (local-only tables have a ps_data_local prefix).
 
                     // To delete the old existing table in the end.
                     existing_tables.insert(&existing.name, existing);
-                } else if !existing.local_only && table.local_only() {
-                    // Migrate from a synced table to a local-only table. We can keep existing rows
-                    // and will also keep existing CRUD data to be uploaded before the switch.
-                    db.exec_safe(&format!(
-                        "ALTER TABLE {} RENAME TO {}",
-                        quote_identifier(&existing.internal_name),
-                        quote_identifier(&table.internal_name()),
-                    ))
-                    .into_db_result(db)?;
-                    continue;
                 } else {
-                    // Identical table exists already, nothing to do.
+                    // Compatible table exists already, nothing to do.
                     continue;
                 }
             }

crates/core/src/sync_local.rs

@@ -5,6 +5,7 @@ use alloc::vec::Vec;
 use serde::Deserialize;
 
 use crate::error::{PSResult, PowerSyncError};
+use crate::schema::inspection::ExistingTable;
 use crate::schema::{PendingStatement, PendingStatementValue, RawTable, Schema};
 use crate::state::DatabaseState;
 use crate::sync::BucketPriority;
@@ -434,22 +435,16 @@ impl<'a> ParsedDatabaseSchema<'a> {
     }
 
     fn add_from_db(&mut self, db: *mut sqlite::sqlite3) -> Result<(), PowerSyncError> {
-        // language=SQLite
-        let statement = db
-            .prepare_v2(
-                "SELECT name FROM sqlite_master WHERE type='table' AND name GLOB 'ps_data_*'",
-            )
-            .into_db_result(db)?;
-
-        while statement.step()? == ResultCode::ROW {
-            let name = statement.column_text(0)?;
-            // Strip the ps_data__ prefix so that we can lookup tables by their sync protocol name.
-            let visible_name = name.get(9..).unwrap_or(name);
-
-            // Tables which haven't been passed explicitly are assumed to not be raw tables.
-            self.tables
-                .insert(String::from(visible_name), ParsedSchemaTable::json_table());
+        let tables = ExistingTable::list(db)?;
+        for table in tables {
+            if !table.local_only {
+                let visible_name = table.name;
+
+                self.tables
+                    .insert(visible_name, ParsedSchemaTable::json_table());
+            }
         }
+
         Ok(())
     }
 }

dart/test/schema_test.dart

@@ -91,9 +91,8 @@ void main() {
             throwsA(isA<SqliteException>()));
 
         // Data should still be there.
-        expect(db.select('SELECT * FROM users'), [
-          {'id': 'synced-id', 'name': 'name'}
-        ]);
+        expect(db.select('SELECT * FROM ps_untyped'), hasLength(1));
+        expect(db.select('SELECT * FROM users'), isEmpty);
 
         // Inserting into local-only table should not record CRUD item.
         db.execute(