Split EmptyExec into PlaceholderRowExec
#8446
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LGTM, thanks @razeghi71
I only have one naming question: which one is preferred? placeholder/Placeholder or place_holder/PlaceHolder
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I tend to think of Placeholder as one word but totally okay with the other one. If you're also okay with |
Great! Other places also use Placeholder like |
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We do have I'll rename |
razeghi71
changed the title
EmptyExec into PlaceHolderRowExecEmptyExec into PlaceholderRowExec
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Thank you @razeghi71 -- I hope to review this PR tomorrow |
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Thank you @razeghi71 -- this PR good to me. I do think it is worth considering a different name for this node (even though I know you and @waynexia have been working to ensure consistent use of PlaceHolder). However I don't think it is required and this is an improvement.
let me know what you think
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| fn data(&self) -> Result<Vec<RecordBatch>> { | ||
| Ok({ | ||
| let n_field = self.schema.fields.len(); |
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I wonder if the schema can ever have more than 0 fields 🤔
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It does, In this case for example:
CREATE TABLE test (c INT) as values(0);
SELECT COUNT(*) from test;|
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| /// Execution plan for empty relation with produce_one_row=true | ||
| #[derive(Debug)] | ||
| pub struct PlaceholderRowExec { |
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What do you think about calling this OneRowExec? Perhaps that would make the use case of this node more clear than the name PlaceholderRowExec.
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I went with PlaceholderRow because it's always a row of null values, with columns named placeholder_{n} that get projected later. But if OneRowExec sounds better to you, I can definitely switch it up. Let me know what you think.
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I think PlaceHolderExec is fine
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I took the liberty of merging up from main to resolve a conflict on this PR |
* add PlaceHolderRowExec * Change produce_one_row=true calls to use PlaceHolderRowExec * remove produce_one_row from EmptyExec, changes in proto serializer, working tests * PlaceHolder => Placeholder --------- Co-authored-by: Andrew Lamb <[email protected]>
Which issue does this PR close?
Closes #8355
Rationale for this change
Explained in the issue. Please note that I've previously tried to do this using
MemoryExecin #8412, but sinceMemoryExecdoesn't have a serializer and it wasn't trivial to implement one, I took the original way proposed in the issue.I named it
PlaceHolderRowExecinstead ofOneRowExecas this is really more like a place holder with null values for columns until a projection gets applied to it and transform it to another format.What changes are included in this PR?
In this PR I'm splitting
EmptyExeccase ofproduce_one_row=truetoPlaceHolderRowExec. What I didn't do here is that I didn't split the same case inEmptyRelation, probably better to do it in a separate PR.Are these changes tested?
Yes. the tests can be find the
PlaceHolderRowExecfile. Also the integration tests are changed to reflect this change.Are there any user-facing changes?
When showing the physical plan, instead of
EmptyExec produce_one_row=valuethere are now two different cases:EmptyExecandPlaceHolderRowExec