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Fix parsing of the foreign key constraint actions in different order #10224

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dbussink
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@dbussink dbussink commented May 5, 2022

On a FOREIGN KEY one can defined an action ON UPDATE and ON DELETE. The parser would only allow one specific order where first the ON DELETE is specified and then the ON UPDATE.

This meant that a query which had it in the reverse order would fail to parse. This also allows bypassing the check on DDL statements that add a foreign key constraint too.

Additionally, we move the schemadiff logic here to be strict for parsing. It was blowing up with a panic on a schema with such a differently ordered foreign key constraint but it should have error on any parser error.

In case schemadiff can't parse something, we can't trust it to do any further operations on the schema.

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  • "Backport me!" label has been added if this change should be backported
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On a FOREIGN KEY one can defined an action ON UPDATE and ON DELETE. The
parser would only allow one specific order where first the ON DELETE is
specified and then the ON UPDATE.

This meant that a query which had it in the reverse order would fail to
parse. This also allows bypassing the check on DDL statements that add a
foreign key constraint too.

Additionally, we move the schemadiff logic here to be strict for
parsing. It was blowing up with a panic on a schema with such a
differently ordered foreign key constraint but it should have error on
any parser error.

In case schemadiff can't parse something, we can't trust it to do any
further operations on the schema.

Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
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github-actions bot commented May 5, 2022

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constraint second_ibfk_1 foreign key (k, j) references simple (a, b) on update no action,
constraint second_ibfk_1 foreign key (k, j) references simple (a, b) on update cascade
)`,
output: `create table t (
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This specific output was needed since the parser parses the actions into a struct so the ordering specifically of this is lost.

We have verified though that MySQL doesn't accidentally allows a list of these items, just only both orders so there's no potential semantic difference due to the different order.

@dbussink dbussink changed the title Fix parsing of the foreign key constraints in different order Fix parsing of the foreign key constraint actions in different order May 5, 2022
@mattlord mattlord merged commit 4dd5a11 into vitessio:main May 5, 2022
@mattlord mattlord deleted the dbussink/fix-foreign-key-parsing branch May 5, 2022 18:53
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