The title says "A contemplation by Ethan, the Ezrahite" (89:1). Who was Ethan, and when was the psalm written?

The title says only those words. It gives no date and no occasion. The Hebrew Bible has the word Ezrahite three times: here, in the title of the psalm before, "A contemplation by Heman, the Ezrahite" (Psalm 88:1), and in 1 Kings, which says Solomon "was wiser than all men—wiser than Ethan the Ezrahite, Heman, Calcol, and Darda, the sons of Mahol" (1 Kings 4:31). Other verses name an Ethan too: among "The sons of Zerah" (1 Chronicles 2:6), and among the singers (1 Chronicles 15:17, 15:19). The chapter on 1 Chronicles 6 sets these verses side by side in its honest question on Heman and Ethan, and the chapter on Psalm 88 does the same for Heman. None of these verses says that the Ethan it names made this psalm, and these notes don't say so either. The psalm names no king after David. It speaks of "your anointed" (89:38, 89:51) and of what has happened to him, but doesn't say which king it means or when, and these notes don't guess. No New Testament verse names a writer for Psalm 89.