create table X(...) => insert into obj$ values (... 'X',...)

Hello

I am trying to get into deeper knowledge on the x$, v$ and X$ (such as user$, fet$, obj$) tables/views.

Are the following assumptions correct:

x$
  if the sql parser sees an x$ table, it knows, it's not physically   stored on harddisk (or tablespaces) but rather is referencing   some bytes in memory. Therefor, it will return the values   of the memory disguised as table data. They cannot be altered
(using insert, updated and delete)

v$
  the same goes for v$ views. The parser realizes these are not   physically stored anywhere but are referencing data that the   instance stores (or accumulates over time). They somethimes   can be altered but this will not generate redo nor undo
(as this is not data on the hd but in the memory)

X$
  These tables are undistinguishable from ordinary (user created) tables.   They reside on a tablespace (system); accordingly, these tables   _could_ (but is not allowed to do by oracle inc.) be altered and would   generate redo/undo if one did.

I also understand, that if I issue a statement like create table XYZ (a number, b varchar2(34)) this will somewhere translate into a
insert into obj$ values (....,'XYZ',...) (though I am not 100% sure of this)

But how can the table obj$ be created if this table must be around when (not if) the table is created.

Anything?

MK Received on Mon May 27 2002 - 23:53:26 CDT