IDEMPIERE-6166 PostgreSQL DUAL table with more than one record (#2387)

* IDEMPIERE-6166 PostgreSQL DUAL table with more than one record

- create unique index on dual.dummy for postgresql

* - implement suggestion from hengsin - make dual a view instead of a table
- fix similar issue with the table dbreplicasyncverifier - it must ensure to contain just one table - running again a COPY command must fail

db/postgresql/functions/dbreplicasyncverifier.sql

@@ -0,0 +1,29 @@
+/*
+CREATE TABLE dbreplicasyncverifier (lastupdate date)
+;
+
+INSERT INTO dbreplicasyncverifier values (to_date('1900-01-01 00:00:00', 'yyyy-mm-dd HH24:MI:SS'))
+;
+*/
+
+CREATE OR REPLACE FUNCTION forbid_multiple_rows_in_dbreplicasyncverifier()
+RETURNS TRIGGER AS $$
+BEGIN
+    -- Check if the table already contains a row
+    IF (SELECT COUNT(*) FROM dbreplicasyncverifier) > 0 THEN
+        RAISE EXCEPTION 'Table can only contain one row.';
+    END IF;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql
+;
+
+CREATE TRIGGER single_row_only_trigger_dbreplicasyncverifier
+BEFORE INSERT ON dbreplicasyncverifier
+FOR EACH ROW
+EXECUTE FUNCTION forbid_multiple_rows_in_dbreplicasyncverifier()
+;
+
+CREATE OR REPLACE RULE delete_dbreplicasyncverifier AS ON DELETE TO dbreplicasyncverifier DO INSTEAD NOTHING
+;
+

db/postgresql/functions/register_migration_script.sql

@@ -41,13 +41,6 @@ END;
 $BODY$
 LANGUAGE plpgsql;
 
-CREATE TABLE dual ( dummy char );
-
-INSERT INTO dual values ( 'X' );
-
-CREATE OR REPLACE RULE insert_dual AS ON INSERT TO dual DO INSTEAD NOTHING;
-
-CREATE OR REPLACE RULE update_dual AS ON UPDATE TO dual DO INSTEAD NOTHING;
-
-CREATE OR REPLACE RULE delete_dual AS ON DELETE TO dual DO INSTEAD NOTHING;
+CREATE VIEW dual AS SELECT 'X'::varchar AS dummy
+;
 

migration/iD11/oracle/202406072107_IDEMPIERE-6166.sql

@@ -0,0 +1,5 @@
+-- IDEMPIERE-6166 PostgreSQL DUAL table with more than one record
+SELECT register_migration_script('202406072107_IDEMPIERE-6166.sql') FROM dual;
+
+-- placeholder, this is just required for postgresql
+

migration/iD11/postgresql/202406072107_IDEMPIERE-6166.sql

@@ -0,0 +1,30 @@
+-- IDEMPIERE-6166 PostgreSQL DUAL table with more than one record
+SELECT register_migration_script('202406072107_IDEMPIERE-6166.sql') FROM dual;
+
+DROP TABLE IF EXISTS dual
+;
+
+CREATE VIEW dual AS SELECT 'X'::varchar AS dummy
+;
+
+DROP RULE insert_dbreplicasyncverifier ON dbreplicasyncverifier
+;
+
+CREATE OR REPLACE FUNCTION forbid_multiple_rows_in_dbreplicasyncverifier()
+RETURNS TRIGGER AS $$
+BEGIN
+    -- Check if the table already contains a row
+    IF (SELECT COUNT(*) FROM dbreplicasyncverifier) > 0 THEN
+        RAISE EXCEPTION 'Table dbreplicasyncverifier can only contain one row.';
+    END IF;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql
+;
+
+CREATE TRIGGER single_row_only_trigger_dbreplicasyncverifier
+BEFORE INSERT ON dbreplicasyncverifier
+FOR EACH ROW
+EXECUTE FUNCTION forbid_multiple_rows_in_dbreplicasyncverifier()
+;
+