Create cycle_notification_history_in_batches.sql

database_maintenance/cycle_notification_history_in_batches.sql

@@ -0,0 +1,31 @@
+-- Call once at the start of the process
+
+CREATE TABLE notification_history_pivot AS SELECT * from notification_history WHERE 1=2;
+
+SELECT id
+INTO nh_temp
+FROM notification_history;
+
+SELECT COUNT(*) AS 'Total number of rows in nh' FROM nh_temp;
+
+DELETE FROM nh_temp t
+USING notification_history_pivot p
+WHERE t.id = p.id;
+
+SELECT COUNT(*) AS 'Number of rows remaining that need moving across from nh to nh_pivot' FROM nh_temp;
+
+-- In each function call, using same database connection as used for the above SQL (needs to be in a transaction; this can be inside a stored function or in a transaction from the code)
+
+INSERT INTO notification_history_pivot
+SELECT n.*
+FROM notification_history n,
+     nh_temp t
+WHERE n.id = t.id;
+
+DELETE FROM nh_temp t
+USING notification_history_pivot p
+WHERE t.id = p.id;
+
+SELECT COUNT(*) from nh_temp;
+
+-- Loop until this result is zero.