sql/schemachanger/scplan: allow plan to move to NonRevertible earlier #84430
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FWIW I'm totally fine with these, they are well-motivated and easy to understand.
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Ah. This makes sense.
This logic belongs in the bowels of opgen, though, along with what determines the revertible boolean field on each op-edge. You'll find that it's quite similar.
In fact, perhaps this revertible boolean field should be replaced by an enum with three states:
- revertible, failure possible;
- revertible, failure not possible;
- not revertible, failure not possible.
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I moved this into opgen in the newly added first commit. It was the right thing to do, but took a little bit of elbow grease.
I've left two booleans as I found it easier to deal with for now, do you feel strongly?
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No, I don't feel strongly about that.
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This change reworks opgen to require the emit functions to specify the type of op they'll emit. This allows us to statically determine the op type and then use that to determine whether there are any remaining ops which might fail. Release note: None
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This is critical for DROP COLUMN. In `DROP COLUMN` we cannot perform the primary index swap until the dropping column reaches `DELETE_ONLY`, which is not revertible. The primary index swap itself is revertible. Given this fact, we need a mechanism to be able to "promote" revertible operations (operations which don't destroy information or cause irrevocable visible side effects) to be grouped with or after non-revertible operations. This commit makes that happen naturally. Release note: None
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This is critical for DROP COLUMN. In
DROP COLUMNwe cannot perform theprimary index swap until the dropping column reaches
DELETE_ONLY, which isnot revertible. The primary index swap itself is revertible. Given this fact,
we need a mechanism to be able to "promote" revertible operations (operations
which don't destroy information or cause irrevocable visible side effects) to
be grouped with or after non-revertible operations. This commit makes that
happen naturally.
Release note: None