Ensure the row count is preserved when coalescing over empty records #3439
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@@ Coverage Diff @@
## master #3439 +/- ##
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+ Coverage 85.61% 85.67% +0.06%
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Files 297 298 +1
Lines 54490 54647 +157
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+ Hits 46650 46821 +171
+ Misses 7840 7826 -14
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Thanks @isidentical -- this looks great. I left some small suggestions but they are not required -- let me know if you want to address them in this PR or a follow on
Thanks again 🏅
| let mut options = RecordBatchOptions::default(); | ||
| options.row_count = Some(row_count); |
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As an FYI (not important) you can write this same pattern in what is likely more idiomatic rust (avoid mut) like:
| let mut options = RecordBatchOptions::default(); | |
| options.row_count = Some(row_count); | |
| let options = RecordBatchOptions{ | |
| row_count:Some(row_count), | |
| ..Default::default() | |
| }; |
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This seems to fail since RecordBatchOptions is non-exhaustive and comes directly from arrow-rs. I am not really familiar with this part of Rust semantics, but there seems to be an existing issue about it.
error[E0639]: cannot create non-exhaustive struct using struct expression
--> /home/isidentical/projects/arrow-datafusion/datafusion/core/src/physical_plan/coalesce_batches.rs:295:19
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295 | let options = RecordBatchOptions {
| ___________________^
296 | | row_count: Some(row_count),
297 | | ..Default::default()
298 | | };
| |_____^
For more information about this error, try `rustc --explain E0639`.
Is there any way to achieve it? The only other example of RecordBatchOptions construction present in DF is the following which uses the same pattern as the code present in this PR but I'd be happy to refactor both if there is a more idiomatic way.
https://github.com/apache/arrow-datafusion/blob/9956f80f197550051db7debae15d5c706afc22a3/datafusion/core/src/physical_plan/file_format/mod.rs#L286-L288
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Thanks for trying @isidentical -- I will file a follow on in arrow-rs to make this API more ergonomic
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Filed apache/arrow-rs#2728 as a follow on (I also hit the same thing in #3454 FWIW)
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FYI apache/arrow-rs#2729 fixed this issue and #3483 includes using the new API.
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Which issue does this PR close?
Closes #3283.
Rationale for this change
The row count information is required for the validation happening during the
RecordBatchconstruction. Luckily we already calculate it and propagate it in the stream handler code, but just don't preserve it when creating the final record.This PR also changes the SQL test code to never double-optimize logical plans (as it used to) since that would hide this problem (and maybe different ones in the future).
What changes are included in this PR?
This PR now creates the final record with the propagated
row_countfor the cases like #3283 where the schema might not contain any fields at all and the validation logic in arrow-rs would fail.Are there any user-facing changes?
This is a bug fix in general. It also includes a change in our internal tooling to never double-optimize logical plans, which the reasoning is provided inn #3283.