Support for pg ADD GENERATED in ALTER COLUMN statements

[tobyhede]

ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( sequence_options ) ]

Includes the identity/sequence options

ALTER TABLE t ALTER COLUMN id ADD GENERATED ALWAYS AS IDENTITY
ALTER TABLE t ALTER COLUMN id ADD GENERATED BY DEFAULT AS IDENTITY
ALTER TABLE t ALTER COLUMN id ADD GENERATED AS IDENTITY
ALTER TABLE t ALTER COLUMN id ADD GENERATED AS IDENTITY ( INCREMENT 1 MINVALUE 1 )
ALTER TABLE t ALTER COLUMN id ADD GENERATED AS IDENTITY ( )

Fixes #988

[tobyhede]

@alamb Working on the broken test ... not happening locally.

[tobyhede]

Actually. PEBKAC. As always 🤦

[alamb]

Thank you for the contribution @tobyhede -- this looks almost good to me with the exception of some of the error handling, as I have pointed out above

[alamb]

Why is this ignoring the result? shouldn't it at least check and return the error, like:

Suggested change

	let _ = self.expect_keywords(&[Keyword::AS, Keyword::IDENTITY]);
	self.expect_keywords(&[Keyword::AS, Keyword::IDENTITY])?;

[alamb]

Likewise here, I don't understand why the error is ignored. If there is a reason maybe we can add a comment.

I also wonder if we are sure that if parse_create_sequence_options returns an error that it hasn't consumed any tokens

[alamb]

Given there is some seemingly non trival error handling, can you please add some tests that hit the errors (e.g. when the two statements I identified above actually return an error?)

[tobyhede]

On it

[coveralls]

Pull Request Test Coverage Report for Build 7380471401

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 87.821%

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Totals
Change from base Build 7378974912:	0.001%
Covered Lines:	18697
Relevant Lines:	21290

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💛 - Coveralls

[tobyhede]

@alamb Added the missed errors, and added tests to cover the cases. Sorry for missing such basics.

[alamb]

@alamb Added the missed errors, and added tests to cover the cases. Sorry for missing such basics.

No worries at all -- thank you for your continued contributions!