How to add an identity column to an existing delta table.
ALTER TABLE tname ADD COLUMN id BIGINT GENERATED BY DEFAULT AS IDENTITY;
doesn't seem to be supported.
Adding an `IDENTITY` column to an existing delta table (Databricks)
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1 Answers
Yes, apparently you can't add a generated column. ALTER TABLE syntax doesn't seem to allow that.
As a workaround create a table from scratch and copy data:
CREATE TABLE tname_ (
<tname columns>,
id BIGINT GENERATED BY DEFAULT AS IDENTITY
);
INSERT INTO tname_ (<tname columns>) SELECT * FROM tname;
DROP TABLE tname;
ALTER TABLE tname_ RENAME TO tname;
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