Sie können eine einfache rekursive Abfrage schreiben, die mit allen Ansichten beginnt, die nicht von anderen abhängen, und rekursiv die Ansichten hinzufügt, die von diesen abhängen. Geben Sie dann die View-Definition für diese Views in der richtigen Reihenfolge aus, und Sie haben Ihr Skript:
WITH RECURSIVE viewids AS (
/* all views that don't depend on other views */
SELECT t.oid, 1 as level
FROM pg_class t
JOIN pg_rewrite AS r ON r.ev_class = t.oid
WHERE r.rulename = '_RETURN'
AND t.relkind = 'v'
AND t.relnamespace NOT IN ('pg_catalog'::regnamespace,
'information_schema'::regnamespace,
'pg_toast'::regnamespace)
AND NOT EXISTS (
/* depends on a view */
SELECT 1
FROM pg_depend AS d
JOIN pg_class AS t2 ON d.refobjid = t2.oid
WHERE d.objid = r.oid
AND d.classid = 'pg_rewrite'::regclass
AND d.refclassid = 'pg_class'::regclass
AND d.deptype = 'n'
AND d.refobjsubid <> 0
AND t2.relkind = 'v'
)
AND NOT EXISTS (
/* depends on an extension */
SELECT 1
FROM pg_depend
WHERE objid = t.oid
AND classid = 'pg_class'::regclass
AND refclassid = 'pg_extension'::regclass
AND deptype = 'e'
)
UNION ALL
/* all views that depend on these views */
SELECT t.oid, viewids.level + 1
FROM pg_class AS t
JOIN pg_rewrite AS r ON r.ev_class = t.oid
JOIN pg_depend AS d ON d.objid = r.oid
JOIN viewids ON viewids.oid = d.refobjid
WHERE t.relkind = 'v'
AND r.rulename = '_RETURN'
AND d.classid = 'pg_rewrite'::regclass
AND d.refclassid = 'pg_class'::regclass
AND d.deptype = 'n'
AND d.refobjsubid <> 0
)
/* order the views by level, eliminating duplicates */
SELECT format('CREATE VIEW %s AS%s',
oid::regclass,
pg_get_viewdef(oid::regclass))
FROM viewids
GROUP BY oid
ORDER BY max(level);
