Psalm 78/Notes/Phrasal.v. 23.828593
From Psalms: Layer by Layer
v. 23 – It would have been unproblematic to make שָׁמַ֣יִם a definite dependent of the construct chain (see, e.g., Ps 19:7; 79:2; 104:12; 148:4, etc.), so instead of the doors of heaven, שָׁמַ֣יִם here seems to indicate the genus, type of door.