pdet commented on issue #38837:
URL: https://github.com/apache/arrow/issues/38837#issuecomment-2129036138

   > * arrow.cpp#L389-L400
   
   In DuckDB, these statistics are created as a callback function that exists 
in the scanner. For example, in our Arrow integration, the statistics of the 
scanner are basically empty, as you can see 
[here](https://github.com/duckdb/duckdb/blob/main/src/function/table/arrow.cpp#L406).
   
   In practice, we need to be able to get the statistics at bind time.
   
   The code at [this 
link](https://github.com/duckdb/duckdb/blob/v0.10.3/src/function/table/arrow.cpp#L389-L400)
 is not really related to cardinality estimation. This code sets the size of 
the current data chunk we scanned, which will later be pushed to upper nodes.
   In DuckDB these statistics are created as a callback function that exists in 
the scanner. For example in our arrow integration the statistics of the scanner 
are basically empty, as you can see 
[here](https://github.com/duckdb/duckdb/blob/main/src/function/table/arrow.cpp#L406).
   
   In practice, we would need to be able to get the statistics at Bind time.
   
   
https://github.com/duckdb/duckdb/blob/v0.10.3/src/function/table/arrow.cpp#L389-L400
 Here is not really related about cardinality estimation. This code sets the 
size of the current data_chunk we scanned and that will be later pushed to 
upper nodes.


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