perf: Cache get_tables values

- To avoid redundant db calls

frappe/database/database.py

@@ -769,7 +769,16 @@ class Database(object):
 		return ("tab" + doctype) in self.get_tables()
 
 	def get_tables(self):
-		return [d[0] for d in self.sql("select table_name from information_schema.tables where table_schema not in ('pg_catalog', 'information_schema')")]
+		tables = frappe.cache().get_value('db_tables')
+		if not tables:
+			table_rows = self.sql("""
+				SELECT table_name
+				FROM information_schema.tables
+				WHERE table_schema NOT IN ('pg_catalog', 'information_schema')
+			""")
+			tables = set([d[0] for d in table_rows])
+		frappe.cache().set_value('db_tables', tables)
+		return tables
 
 	def a_row_exists(self, doctype):
 		"""Returns True if atleast one row exists."""

frappe/database/schema.py

@@ -31,6 +31,7 @@ class DBTable:
 
 	def sync(self):
 		if self.is_new():
+			frappe.cache().delete_key('db_tables')
 			self.create()
 		else:
 			frappe.cache().hdel('table_columns', self.table_name)