Re: Undocumented feature ALTER SESSION SET CURRENT_SCHEMA = xxx

Hi All,

There are three reasons why ALTER SESSION SET CURRENT_SCHEMA remains undocumented.

The first is to protect customers still on pre 7.1 versions of the server, because there was a major security loophole in the feature.

The second is that Oracle's implementation predates the SQL standard and does not comply with it.

The third and most significant reason is that as implemented the feature is not always safe. The reason for this is that Oracle has no mechanism for cache coherency or consistency between its various cursor caches. There are cases where this does not matter, for example if the statement is used immediately after a connect and never again. However, you should check with Oracle Support to see whether any other non-trivial use of the statement is safe.

There is good reason to use this statement (rather than referencing via synonyms) in large multi-user OLTP applications. It removes the need for negative dependency tracking and thereby saves a LOT of SGA memory and latch gets.

Hope this helps,
Regards,
Steve Adams
steveadams_at_acslink.net.au Received on Wed Dec 17 1997 - 00:00:00 CST