{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655786374", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655786374, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTc4NjM3NA==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T22:16:54Z", "updated_at": "2020-07-08T22:16:54Z", "author_association": "OWNER", "body": "According to https://www.sqlite.org/lang_altertable.html#making_other_kinds_of_table_schema_changes the hardest bits to consider are how to deal with existing foreign key relationships, triggers and views.\r\n\r\nI'm OK leaving views as an exercise for the caller - many of these transformations may not need any view changes at all.\r\n\r\nForeign key relationships are important: it should handle these automatically as effectively as possible.\r\n\r\nLikewise trigger changes: need to think about what this means.", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655785396", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655785396, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTc4NTM5Ng==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T22:14:10Z", "updated_at": "2020-07-08T22:14:10Z", "author_association": "OWNER", "body": "Work in progress: not quite right yet, I need smarter logic for how renamed columns are reflected in the generated `INSERT INTO ... SELECT ...` query:\r\n```python\r\n    def transform_table(\r\n        self,\r\n        columns=None,\r\n        rename=None,\r\n        change_type=None,\r\n        pk=None,\r\n        foreign_keys=None,\r\n        column_order=None,\r\n        not_null=None,\r\n        defaults=None,\r\n        hash_id=None,\r\n        extracts=None,\r\n    ):\r\n        assert self.exists(), \"Cannot transform a table that doesn't exist yet\"\r\n        columns = columns or self.columns_dict\r\n        if rename is not None or change_type is not None:\r\n            columns = {rename.get(key, key): change_type.get(key, value) for key, value in columns.items()}\r\n        new_table_name = \"{}_new_{}\".format(self.name, os.urandom(6).hex())\r\n        previous_columns = set(self.columns_dict.keys())\r\n        with self.db.conn:\r\n            columns = {name: value for (name, value) in columns.items()}\r\n            new_table = self.db.create_table(\r\n                new_table_name,\r\n                columns,\r\n                pk=pk,\r\n                foreign_keys=foreign_keys,\r\n                column_order=column_order,\r\n                not_null=not_null,\r\n                defaults=defaults,\r\n                hash_id=hash_id,\r\n                extracts=extracts,\r\n            )\r\n            # Copy across data - but only for columns that exist in both\r\n            new_columns = set(columns.keys())\r\n            columns_to_copy = new_columns.intersection(previous_columns)\r\n            copy_sql = \"INSERT INTO [{new_table}] ({new_cols}) SELECT {old_cols} FROM [{old_table}]\".format(\r\n                new_table=new_table_name,\r\n                old_table=self.name,\r\n                old_cols=\", \".join(\"[{}]\".format(col) for col in columns_to_copy),\r\n                new_cols=\", \".join(\"[{}]\".format(rename.get(col, col)) for col in columns_to_copy),\r\n            )\r\n            self.db.conn.execute(copy_sql)\r\n            # Drop the old table\r\n            self.db.conn.execute(\"DROP TABLE [{}]\".format(self.name))\r\n            # Rename the new one\r\n            self.db.conn.execute(\r\n                \"ALTER TABLE [{}] RENAME TO [{}]\".format(new_table_name, self.name)\r\n            )\r\n        return self\r\n```", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655783875", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655783875, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTc4Mzg3NQ==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T22:09:51Z", "updated_at": "2020-07-08T22:10:16Z", "author_association": "OWNER", "body": "I can have a convenient `change_type={...}` parameter for changing column types too.", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655782477", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655782477, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTc4MjQ3Nw==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T22:06:23Z", "updated_at": "2020-07-08T22:06:23Z", "author_association": "OWNER", "body": "Thinking about the method signature:\r\n```python\r\n    def transform_table(\r\n        self,\r\n        columns,\r\n        pk=None,\r\n        foreign_keys=None,\r\n        column_order=None,\r\n        not_null=None,\r\n        defaults=None,\r\n        hash_id=None,\r\n        extracts=None,\r\n    ):\r\n```\r\nThis requires the caller to provide the exact set of columns for the new table.\r\n\r\nIt would be useful if this was optional - if you could omit the columns and have it automatically use the previous columns. This would let you change things like the primary key or the column order using the other arguments.\r\n\r\nEven better: allow column renaming using an optional `rename={...}` argument:\r\n\r\n```python\r\ndb[\"dogs\"].transform_table(rename={\"name\": \"dog_name\"})\r\n```", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655778058", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655778058, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTc3ODA1OA==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T21:54:30Z", "updated_at": "2020-07-08T21:54:30Z", "author_association": "OWNER", "body": "Don't forget this step:\r\n>  If foreign key constraints are enabled, disable them using PRAGMA foreign_keys=OFF. ", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655677909", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655677909, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTY3NzkwOQ==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T18:16:39Z", "updated_at": "2020-07-08T18:16:39Z", "author_association": "OWNER", "body": "Since neither the term \"transform\" or \"migrate\" are used in the codebase at the moment, I think I'll go with `.transform_table()` - that leaves the term \"migrate\" available for any future database migrations system (similar to Django's).", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655677396", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655677396, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTY3NzM5Ng==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T18:15:39Z", "updated_at": "2020-07-08T18:15:39Z", "author_association": "OWNER", "body": "Alternative possible names:\r\n- `.transform_table()`\r\n- `.migrate()`\r\n- `.transform()`\r\n\r\nI'm torn between `.migrate_table()` and `.transform_table()`.", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655677099", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655677099, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTY3NzA5OQ==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T18:15:02Z", "updated_at": "2020-07-08T18:15:02Z", "author_association": "OWNER", "body": "I'm not so keen on that chained API - it's pretty complicated.\r\n\r\nHere's an idea for a much simpler interface. Essentially it lets you say \"take table X and migrate its contents to a new table with this structure - then atomically rename the tables to switch them\":\r\n```python\r\ndb[\"mytable\"].migrate_table({\"id\": int, \"name\": str\"}, pk=\"id\")\r\n```\r\nThe `migrate_table()` method would take the same exact signature as the `table.create()` method: https://github.com/simonw/sqlite-utils/blob/a236a6bc771a5a6a9d7e814f1986d461afc422d2/sqlite_utils/db.py#L615-L625", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}
{"html_url": "https://github.com/simonw/sqlite-utils/issues/114#issuecomment-655290625", "issue_url": "https://api.github.com/repos/simonw/sqlite-utils/issues/114", "id": 655290625, "node_id": "MDEyOklzc3VlQ29tbWVudDY1NTI5MDYyNQ==", "user": {"value": 9599, "label": "simonw"}, "created_at": "2020-07-08T05:15:45Z", "updated_at": "2020-07-08T05:15:45Z", "author_association": "OWNER", "body": "Ideally this would all happen in a single transaction, such that other processes talking to the database would not see any inconsistent state while the table copy was taking place. Need to confirm that this is possible. Also refs transactions thoughts in #121.", "reactions": "{\"total_count\": 0, \"+1\": 0, \"-1\": 0, \"laugh\": 0, \"hooray\": 0, \"confused\": 0, \"heart\": 0, \"rocket\": 0, \"eyes\": 0}", "issue": {"value": 621989740, "label": "table.transform() method for advanced alter table"}, "performed_via_github_app": null}