preupgrd.sql

preupgrd.sql is the pre-upgrade script shipped with Oracle 19c (and earlier releases under similar names). It runs against the source instance before any migration procedure begins, producing a text report that captures the database state relative to the target version’s requirements.

What it does #

The script queries the data dictionary and internal views to detect:

• INVALID objects that could block the post-upgrade recompilation phase
• initialization parameters that are deprecated or removed in the target version
• obsolete features still active (e.g., COMPATIBLE mismatches, out-of-range DB_BLOCK_SIZE)
• timezone, character set, and optional component issues that cannot be migrated automatically

Output is written to $ORACLE_BASE/cfgtoollogs/db_unique_name/preupgrade/ as plain text files and, in recent versions, as ready-to-run corrective SQL scripts.

sqlplus / as sysdba @$ORACLE_HOME/rdbms/admin/preupgrd.sql

When to use it #

preupgrd.sql should be run weeks before cutover, not on migration night. The DBA uses the report to plan remediation: recompiling invalid objects, removing obsolete parameters, updating optional components. In critical production environments — such as 8 TB financial databases — the report feeds directly into the rollback plan and maintenance window estimation.

Operational notes #

Oracle ships updated versions of the script with each PSU/RU. Before running it, confirm you are using the copy from the target version’s ORACLE_HOME, not the source’s: that is where the up-to-date validation logic resides.