Yury Zhuravlev <u.zhurav...@postgrespro.ru> writes:
> New patch version in attachment.  

I've committed this with a number of revisions, mostly but not entirely
cosmetic.  Worthy of note:

* I did not like the way you were inserting the replacement subscript
values:

+                       arrays = (AnyArrayType 
*)DatumGetArrayTypeP(array_source);
+                       indexexpr = AARR_LBOUND(arrays)[i] + 
AARR_DIMS(arrays)[i] - 1;

If the source array is toasted, this causes an extra detoast operation
for *each* omitted subscript.  That could be pretty high overhead for
a large array.  The best way to avoid that is to postpone the actual
substitution of the replacement subscript values into array_get_slice
and array_set_slice; which complicates their APIs a bit more, but those
were pretty long argument lists already.

* Having done that, there was no very good reason for the blanket
prohibition on using omitted subscripts in the slice-set case.  We only
really need to fail if we're constructing the array from scratch, when
we don't have any existing subscript limits to substitute.

                        regards, tom lane


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