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Help with an interesting Postgres question: Why isn't an Index Only Scan used on a partition accessed via the parent table?.
create table test(txt text);
alter table test
add constraint case_insensitive_unique
exclude using gist(upper(txt) with =);
CREATE TABLE
ALTER TABLE
insert into test(txt) select 'hello';
INSERT 0 1
insert into test(txt) select 'Hello';
ERROR: conflicting key value violates exclusion constraint "case_insensitive_unique" DETAIL: Key (upper(txt))=(HELLO) conflicts with existing key (upper(txt))=(HELLO).
alter table test drop constraint case_insensitive_unique;
ALTER TABLE
CREATE UNIQUE INDEX UniqueValue ON test (UPPER(txt));
CREATE INDEX
insert into test(txt) select 'Hello';
ERROR: duplicate key value violates unique constraint "uniquevalue" DETAIL: Key (upper(txt))=(HELLO) already exists.
insert into test(txt) select 'heLLo';
ERROR: duplicate key value violates unique constraint "uniquevalue" DETAIL: Key (upper(txt))=(HELLO) already exists.
table test;
| txt |
|---|
| hello |
SELECT 1