From c1d74f01e0c8cdd2f73ebf2913826bab2b0c3f78 Mon Sep 17 00:00:00 2001
From: Heng Sin Low <hengsin@gmail.com>
Date: Mon, 30 Apr 2007 15:45:05 +0000
Subject: [PATCH] [ 1707540 ] Dependency problem when modifying AD Columns and
 Sync.

---
 .../316-trunk/postgresql/012_alter_column.sql | 111 ++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 migration/316-trunk/postgresql/012_alter_column.sql

diff --git a/migration/316-trunk/postgresql/012_alter_column.sql b/migration/316-trunk/postgresql/012_alter_column.sql
new file mode 100644
index 0000000000..74ba493905
--- /dev/null
+++ b/migration/316-trunk/postgresql/012_alter_column.sql
@@ -0,0 +1,111 @@
+create or replace function altercolumn(tablename name, columnname name, datatype name,
+nullclause varchar, defaultclause varchar) returns void as $$
+declare
+   command text;
+   viewtext text[];
+   viewname name[];
+   dropviews name[];
+   i int;
+   j int;
+   v record;
+   sqltype       text;
+   sqltype_short text;
+   typename name;
+begin
+   if datatype is not null then
+	select pg_type.typname, format_type(pg_type.oid, pg_attribute.atttypmod)
+        into typename, sqltype
+        from pg_class, pg_attribute, pg_type
+        where relname = lower(tablename)
+        and relkind = 'r'
+        and pg_class.oid = pg_attribute.attrelid
+        and attname = lower(columnname)
+        and atttypid = pg_type.oid;
+        sqltype_short := sqltype;
+        if typename = 'numeric' then
+	   sqltype_short := replace(sqltype, ',0', '');
+        elsif strpos(sqltype,'character varying') = 1 then
+	   sqltype_short := replace(sqltype, 'character varying', 'varchar');
+        elsif sqltype = 'timestamp without time zone' then
+           sqltype_short := 'timestamp';
+        end if;
+        if lower(datatype) <> sqltype and lower(datatype) <> sqltype_short then
+		i := 0;
+		for v in select a.relname, a.oid 
+			from pg_class a, pg_depend b, pg_depend c, pg_class d, pg_attribute e
+			where a.oid = b.refobjid
+			and b.objid = c.objid
+			and b.refobjid <> c.refobjid
+			and b.deptype = 'n'
+			and c.refobjid = d.oid
+			and d.relname = lower(tablename)
+			and d.relkind = 'r'
+			and d.oid = e.attrelid
+			and e.attname = lower(columnname)
+			and c.refobjsubid = e.attnum
+			and a.relkind = 'v'
+		 loop
+		    i := i + 1;
+		    viewtext[i] := pg_get_viewdef(v.oid);
+		    viewname[i] := v.relname;
+		end loop;
+		if i > 0 then
+		   begin
+		     for j in 1 .. i loop
+		        command := 'drop view ' || viewname[j];
+		        execute command;
+		        dropviews[j] := viewname[j];
+		     end loop;
+                     exception
+                        when others then
+                          i := array_upper(dropviews, 1);
+                          if i > 0 then
+                             for j in 1 .. i loop
+                                command := 'create or replace view ' || dropviews[j] || ' as ' || viewtext[j];
+		                execute command;
+                             end loop;
+                          end if;
+                          raise exception 'Failed to recreate dependent view';
+                   end;
+		end if;
+		command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' type ' || lower(datatype);
+		execute command;
+                i := array_upper(dropviews, 1);
+		if i > 0 then
+		   for j in 1 .. i loop
+		     command := 'create or replace view ' || dropviews[j] || ' as ' || viewtext[j];
+		     execute command;
+		   end loop;
+		end if;
+        end if;
+   end if;
+   
+   if defaultclause is not null then
+       if lower(defaultclause) = 'null' then
+          command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' drop default ';
+       else
+	  command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' set default ''' || defaultclause || '''';
+       end if;
+       execute command;
+   end if;
+   
+   if nullclause is not null then
+      if lower(nullclause) = 'not null' then
+          command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' set not null';
+          execute command;
+      elsif lower(nullclause) = 'null' then
+          command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' drop not null';
+          execute command;
+      end if;
+   end if;
+end;
+$$ language plpgsql;
+
+create table t_alter_column
+( tablename name, columnname name, datatype name, nullclause varchar(10), defaultclause varchar(200));
+
+create rule alter_column_rule as on insert to t_alter_column
+do instead select altercolumn(new.tablename, new.columnname, new.datatype, new.nullclause,
+new.defaultclause);
+
+