Add ability to specify catalog as a SQLALchemy table argument #186
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laserkaplan
changed the title
| @@ -44,3 +44,16 @@ def test_offset(dialect): | |||
| statement = select(table).offset(0) | |||
| query = statement.compile(dialect=dialect) | |||
| assert str(query) == 'SELECT "table".id, "table".name \nFROM "table"\nOFFSET :param_1' | |||
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| def test_multiple_catalogs(dialect): | |||
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I'm not sure what "multiple catalogs" mean. Could you rename the test method or leave a comment?
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I have updated the test name to test_catalog_argument.
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I have added an additional bit to this PR since it hadn't been approved/merged yet. The visitors worked when compiling SQL statements, but another method was needed to do the same functionality for DDL statements (like |
| '\n'\ | ||
| 'CREATE TABLE "system".information_schema."table" (\n'\ | ||
| '\tid INTEGER NOT NULL, \n'\ | ||
| '\tPRIMARY KEY (id)\n'\ |
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This DDL looks invalid as Trino query.
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I changed the table to use a fake other catalog so that this test doesn't potentially interfere with the system catalog.
trino/sqlalchemy/compiler.py
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| column, add_to_result_map, include_table, **kwargs | ||
| ) | ||
| table = column.table | ||
| return self.add_catalog(sql, table) |
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I understood the benefit for table, but not sure about column. Could you add a test case to show the usecase?
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I think you're right that it's not needed. Removed the column visitor.
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Hi all, is there anything else blocking this PR from completion? |
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Looks good to me. @mdesmet Can you please take a look as well?
@laserkaplan Please squash the commits now (since it's one logical change).
| table_with_catalog = Table( | ||
| 'table', | ||
| metadata, | ||
| Column('id', Integer, primary_key=True), |
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Is the primary_key=True required for the test? I don't think so. If so please remove it since it distracts attention from what the test and this change is actually about.
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Same for the DDL which is used below - the PRIMARY KEY seems unrelated to the feature being added.
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I see that the primary_key=True just above this one is pre-existing but that should also be removed. Unfortunate that it didn't get caught when it was introduced.
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I went ahead and removed this from both temp tables, as well as in this test.
| CTE = type(None) | ||
| Subquery = type(None) |
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Can you leave a comment here why this is ok to do?
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Yep, this is because the CTE and Subquery classes weren't introduced until SQLAlchemy 1.4. Added a comment.
Is "squash and merge" enabled on the repo for when this is ready to merge? |
AFAIK we don't do squash and merge, only rebase and merge. |
laserkaplan
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| def test_catalogs_argument(dialect): | ||
| statement = select(table_with_catalog) | ||
| query = statement.compile(dialect=dialect) | ||
| assert str(query) == 'SELECT default."table".id \nFROM "other".default."table"' |
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Seems pre-existing but any idea why the schema name doesn't get quoted?
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Looked into this a little. visit_table quotes table names by default, but it checks whether schema names "need" to be quoted (e.g. if they are a reserved word). The PyHive package got around this by considering everything to be a reserved word, which would trigger this quoting. I don't think it's necessary here, but it definitely is a little weird to see schema names not quoted while table names are.
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Thanks for looking into this and explaining. I think we can leave as is for now since from the few queries I tested with special schema names it was able to handle them correctly. I didn't try too hard to break it though to be honest. 😄
This change allows for specifying a
trino_catalogtable argument to SQLALchemy Table objects, which is then checked when compiling statements and prepended to the proper objects. This allows for writing queries that talk to multiple catalogs at the same time.This change was largely implemented by @AlexandreOuellet in the PyHive repository, with some minor edits by @VinceDPM and myself. However, since that repository is no longer well-maintained, and since Trino seems to have better support currently than Presto on the whole, I have switched my own focus to using Trino, and thus wanted to get this functionality working here as well.
As this is the first time I've attempted to contribute here, please let me know if I am missing anything in this PR! It would be great if this could be merged in an efficient manner.