Use "alter system" from C# for ORACLE 10g database

Question

I need for some reason to alter and show the size of db_cahce_size for an ORACLE 10g database from C# (using ODP.NET) I use the following commands on SQL+

"alter system set db_cache_size = Xm scope=both;"

and that command to show it current value

"show parameter db_cache_size;"

but when I tried to issue that commands from C# via ODP.NET command object I got that error [ORA-00900: invalid SQL statement]

It seems that it doesn't accept such kind of command so What to do please to do it?

Answer 1

Why not just create a small procedure to alter the system:

create or replace procedure change_cache_size (Px in number) is
begin
   execute immediate 'alter system set db_cache_size = Xm scope=both';
end;

You can then call this from C#.

In order to find the current value of a parameter in SQL you can query V$PARAMETER

select value
  from v$parameter
 where name = 'db_cache_size'

This can then be queried normally. Alternatively, you can combine them into one using an OUT parameter.

create or replace procedure change_cache_size (Psize out varchar2) is
begin
   execute immediate 'alter system set db_cache_size = Xm scope=both';

   select value into Psize
     from v$parameter
    where name = 'db_cache_size';
end;

I would be extremely wary of changing an initialization parameter in an application in this manner. It's highly indicative that something needs to be changed in your database. I would be much more comfortable coming up with a cache size that works for all applications using a database rather than changing it based on the requirements of one at a single moment in time.

If you want X to be variable then simply make this another parameter:

create or replace procedure change_cache_size (PX in number, Psize out varchar2) is
begin
   execute immediate 'alter system set db_cache_size = ' || X || 'm scope=both';

   select value into Psize
     from v$parameter
    where name = 'db_cache_size';
end;

It's worth noting that you'd now be performing system changes dynamically with user input... ensure you sanitise the input first.