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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Unnest function in BigQuery SQLAlchemy plugin joins twice when selecting other columns","articleBody":"From a customer support request:\r\n\r\nUsing the UNNEST function generates a CROSS JOIN with a table to itself.\r\nA minimal example is included below. The following Python code:\r\n\r\n```\r\nfrom sqlalchemy import create_engine, MetaData, select, func as F, Table, Column, Integer, ARRAY\r\nmetadata = MetaData()\r\ntable = Table(\r\n  \"table1\",\r\n  metadata,\r\n  Column(\"foo\", Integer),\r\n  Column(\"bar\", ARRAY(Integer))\r\n)\r\nengine = create_engine(\"bigquery://\", future=True)\r\nq = select(table.c.foo).where(F.unnest(table.c.bar).column_valued() == 1)\r\nprint(q.compile(engine))\r\n```\r\n\r\nGenerates this query:\r\n\r\n```\r\nSELECT `table1`.`foo` \r\nFROM `table1`, `table1` `table1_1`, unnest(`table1_1`.`bar`) AS `anon_1` \r\nWHERE `anon_1` = %(param_1:INT64)s\r\n```\r\n\r\nI expect it to generate this query instead (note the different FROM clause):\r\n\r\n```\r\nSELECT `table1`.`foo` \r\nFROM `table1`,  unnest(`table1`.`bar`) AS `anon_1` \r\nWHERE `anon_1` = %(param_1:INT64)s\r\n```","author":{"url":"https://github.com/tswast","@type":"Person","name":"tswast"},"datePublished":"2021-10-11T16:45:22.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/353/python-bigquery-sqlalchemy/issues/353"}