pepijnve commented on issue #18548:
URL: https://github.com/apache/datafusion/issues/18548#issuecomment-3507163500
Not a very exciting topic, but if you want some info for the blog post on
the `case` work, here are some numbers I got by running some queries on SF10
lineitems.
### Just a case expression
```
select case l_returnflag
when 'R' then date_part('year', l_shipdate)
when 'A' then date_part('year', l_commitdate)
when 'N' then date_part('year',l_receiptdate)
else null end
from lineitem;
```
**50.0.0**: ~0.492 seconds
**51.0.0**: ~0.278 seconds
### `*`
```
select * from lineitem
```
**50.0.0**: 0.668 seconds
**50.1.0**: 0.668 seconds
### `*` + a case expression
```
select *, case l_returnflag
when 'R' then date_part('year', l_shipdate)
when 'A' then date_part('year', l_commitdate)
when 'N' then date_part('year',l_receiptdate)
else null end
from lineitem;
```
**50.0.0**: ~1.287 seconds -> `case` adds 0,619 seconds
**51.0.0**: ~0.850 seconds -> `case` adds 0,182 seconds
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