TRAP: failed Assert("offsets[i] > offsets[i - 1]"), File: "tidstore.c"

Hi,

While experimenting with query plans, I periodically see test_tidstore 
fail on the assertion in TidStoreSetBlockOffsets().

The cause is that the harness function do_set_block_offsets() forwards 
the SQL array straight to TidStoreSetBlockOffsets(), which has an 
explicit contract:

"The offset numbers 'offsets' must be sorted in ascending order."

array_agg() without ORDER BY gives no such guarantee, and plan shapes 
that reshuffle the input can deliver the offsets out of order and trip 
the Assert.

The issue is minor and doesn't expose any underlying bug, but it is 
still worth fixing: it removes a source of flaky test runs and makes 
life easier for extension developers who reuse the same pattern.

Patch attached.

-- 
regards, Andrei Lepikhov,
pgEdge