CFR: Truncate target table before importing

Also, use `append` strategy again, because `replace` doesn't do the
right DDL.

Author: amotl

CHANGES.md

@@ -4,8 +4,10 @@
 - I/O: Updated to `ingestr>=0.13.61`
 - CFR: Improved log output
 - CFR: Fixed double quoting of table name. Thanks, @karynzv.
-- CFR: When importing, use `replace` policy instead of `append`
+- CFR: When importing, started using `replace` strategy instead of `append`
 - CFR: Improved importing data re. type mapping without NumPy
+- CFR: Truncated target table before importing, using `append`
+  strategy again, because `replace` doesn't do the right DDL.
 
 ## 2025/07/01 v0.0.37
 - Settings: Fixed comparison of `0s` vs `0ms`. Thanks, @hlcianfagna.

cratedb_toolkit/cfr/systable.py

@@ -234,7 +234,7 @@ def load(self):
     def _load(self, path_schema: Path, path_data: Path):
         table_count = 0
         for tablename in tqdm(self.table_names()):
-            tablename_restored = ExportSettings.TABLE_FILENAME_PREFIX + tablename
+            tablename_restored = f"{ExportSettings.TABLE_FILENAME_PREFIX}{tablename}"
 
             path_table_schema = path_schema / f"{ExportSettings.TABLE_FILENAME_PREFIX}{tablename}.sql"
             path_table_data = path_data / f"{ExportSettings.TABLE_FILENAME_PREFIX}{tablename}.{self.data_format}"
@@ -249,14 +249,17 @@ def _load(self, path_schema: Path, path_data: Path):
             schema_sql = path_table_schema.read_text()
             self.adapter.run_sql(schema_sql)
 
+            # Truncate table.
+            self.adapter.run_sql(f"DELETE FROM {self.adapter.quote_relation_name(tablename_restored)};")  # noqa: S608
+
             # Load data.
             try:
                 df: "pd.DataFrame" = pd.DataFrame.from_records(self.load_table(path_table_data))
                 df.to_sql(
                     name=tablename_restored,
                     con=self.adapter.engine,
                     index=False,
-                    if_exists="replace",
+                    if_exists="append",
                     method=insert_bulk,
                 )
             except Exception as ex: