In today’s Oracle 10g training, we were asked to do a exercise on tablespace. I needed to make a tablespace Read Only and Read Write. The syntax was simple, just “ALTER TABLESPACE tbs READ ONLY (READ WRITE”. But while I was playing around, I thought what would happen on the data file after I turned on the Read Only with the tablespace. So I checked the data file (like c:\oracle\oradata\something.dbf) and found out it did not have Read-only attribute even after I altered the tablespace as Read Only. Interesting, it seems the Oracle did not look up the OS level when it deals with the tablespace read-only attributes.
To make things more interesting, I turned on the Read-Only attribute for this tablespace’s data file (Right Click, and check the Read-Only in the proprieties window). Then I went ahead to make more alterations on the tablespace, like increasing the extents size etc. The funny thing was I could see these system changes in Oracle through some dba_ views, but actually they did not take effective. Since I could not insert any new record to a full tablespace even I “successfully” increase the size in Oracle.
Not sure Oracle already aware this situation or not.
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