MOS Note:136697.1 - New HCHECK.SQL for Oracle Database 12c

By Mike Dietrich-Oracle on May 19, 2016

A while back we added this slide to our big slide deck:

The story behind this slide

A large and important customer in the US tested a patch set upgrade - but when they approached the production upgrade from 11.2.0.2 to 11.2.0.3 on a large RAC cluster they've had to cancel the attempt and revert to the previous state.

Reason

They've hit a dictionary corruption somewhere silently sleeping in the database causing no trouble at all so far - until the upgrade touched the broken structures 

They've asked us:
"How could we ensure the database is really healthy and in good state?"

And unfortunately there's no 100% confirmation as there may be an unknown issue we are not aware of. But we can test two things:

• Let RMAN verify the logical integrity of the Oracle blocks
• Let the hcheck.sql script provided by Oracle Support check and test for known dictionary issues

It's actually a general recommendation we give to customers for a long time to check their really important and business critical databases from time to time during off-peak hours. 

Recently Oracle Support updated hcheck.sql to version 4 to include Oracle Database 12c checks as well.

Please find it here:

• MOS Note:136697.1
  hcheck.sql - Script to Check for Known Problems in Oracle8i, Oracle9i, Oracle10g, Oracle 11g and Oracle 12c

출처 : https://blogs.oracle.com/UPGRADE/entry/new_hcheck_sql_for_oracle