should be it

external/duckdb/test/sql/attach/attach_index.test

@@ -0,0 +1,46 @@
+# name: test/sql/attach/attach_index.test
+# description: Issue #6666 - ATTACH fails on duckdb database with INDEX
+# group: [attach]
+
+statement ok
+ATTACH '__TEST_DIR__/attach_index_db.db'
+
+statement ok
+USE attach_index_db
+
+statement ok
+CREATE TABLE tbl_a (
+	a_id INTEGER PRIMARY KEY,
+	value VARCHAR NOT NULL
+)
+
+statement ok
+CREATE INDEX idx_tbl_a ON tbl_a (value)
+
+statement ok
+INSERT INTO tbl_a VALUES (1, 'x')
+
+statement ok
+INSERT INTO tbl_a VALUES (2, 'y')
+
+query II
+SELECT * FROM tbl_a WHERE a_id = 2
+----
+2	y
+
+statement ok
+ATTACH '__TEST_DIR__/other_attach_index.db'
+
+statement ok
+USE other_attach_index
+
+statement ok
+DETACH attach_index_db
+
+statement ok
+ATTACH '__TEST_DIR__/attach_index_db.db'
+
+query II
+SELECT * FROM attach_index_db.tbl_a WHERE a_id = 2
+----
+2	y