Hi,
I was looking at this check in src/backend/parser/parse_utilcmd.c w.r.t. constraint:
if (indclass->values[i] != defopclass ||
attform->attcollation != index_rel->rd_indcollation[i] ||
attoptions != (Datum) 0 ||
index_rel->rd_indoption[i] != 0)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("index \"%s\" column number %d does not have default sorting behavior", index_name, i + 1),
errdetail("Cannot create a primary key or unique constraint using such an index."),
It seems this first came in via `Indexes with INCLUDE columns and their support in B-tree`
If the index has DESC sorting order, why it cannot be used to back a constraint ?
Some concrete sample would help me understand this.
Thanks
