In short, when have statistics gathered in 126.96.36.199 but the query is now running with the 188.8.131.52 optimizer, you may have wrong cardinality estimation on histograms, leading to sub-optimal plans.
All posts by Franck Pachot
Oracle Transparent Data Encryption is available without option on the Oracle Public Cloud: Standard Edition as well as Enterprise Edition (EE, EE-HP EE-EP, ECS). More than that, the DBaaS enforces TDE for any user tablespace even when not specifying in the CREATE TABLESPACE. It you are not familiar with TDE key management (wallets) then you have probably encountered ORA-28374: typed master key not found in wallet. Rather than another tutorial on TDE I’ll try to…
Usually, cursor invalidations do not interrupt the current execution of the cursor. You can even drop a table while a query on it is running and the query may end successfully. However some invalidations will throw internal errors that are catch and the cursor execution restarts transparently. I’ve reproduced one here to show the symptoms: it’s a different EXEC_SQL_ID so the restarts are not accounted within the same SQL Monitoring.
Easier than unplug/plug, you can move pluggable databases with remote cloning. It’s the same idea but you don’t have to manage the files yourself: the are shipped through database link. However, this uses the ‘remote file protocol’ and it fails with version mismatch: ORA-17628: Oracle error 17630 returned by remote Oracle server ORA-17630: Mismatch in the remote file protocol version client server
In the previous post I described how simple it is to unplug a PDB and plug it into a newer version CDB. One goal of dictionary separation in the multitenant architecture is to keep system objects on CDB$ROOT only. Knowing that an upgrade does not touch the application metadata and data, does this make PDB upgrade fast as a simple refresh of metadata links?
12.2 is available in the Oracle Public Cloud DBaaS. If you have a 12.1 DBaaS service, there’s no button to upgrade it. I’ll describe all the possible upgrade procedures and the first one, and the most simple, is to create a new DBaaS service in 12.2 and unplug/plug the PDBs to it.
Two years ago I filled an OTN idea to ‘Constrain PDB datafiles into specific directory’ and made it an enhancement request for 12c Release 2. When you provision a PDB, the PDB admin can create tablespaces and put datafiles anywhere in your system. Of course this is not acceptable in a cloud environment. 12.1 has a parameter for directories (PATH_PREFIX) and 12.2 brings CREATE_FILE_DEST for datafiles.
Now that 12.2 is there, in the Oracle Public Cloud Service, I can share the slides of the presentation I made for Oracle Open World: 12cR2 Single-Tenant: Multitenant Features for All Editions from Franck Pachot I’ll give the same session in French, In Geneva on November 23rd at Oracle Switzerland. Ask me if you want an invitation.