Retain views with listlike indexers setitem

[jbrockmendel]

• closes BUG: df.__setitem__ can be 10x slower than pd.concat(..., axis=1) #37954

xref #38148

[simonjayhawkins]

@jbrockmendel #38148 has been reverted, so can you update this to close #37954 and add the release note in 1.2.0 instead.

[jreback]

lgtm. the perf enhancements hold here (I think so, just checking).?

[jbrockmendel]

lgtm. the perf enhancements hold here (I think so, just checking).?

i timed it at slightly faster than the copying version (likely within the margin of error, dont recall)

[jreback]

great. ping on green (not sure what's going on with CI).

[jbrockmendel]

not sure what's going on with CI

AFAICT its just backed up. A lot got merged in a short time!

[simonjayhawkins]

@jreback green

[jreback]

thanks @jbrockmendel

I think we going to backport this @simonjayhawkins (not sure if the regression was on 1.1.5)?

[simonjayhawkins]

no evidence this was a regression. maybe can do some digging post 1.2.0rc0 and maybe backport to 1.1.5 and move release note before 1.2.0

but for now, I would say this is not being backported.