Category Archives: Oracle DBA Interview Questions

Explain an ORA-01555. | Oracle DBA Questions

You get this error when you get a snapshot too old within rollback. It can usually be solved by increasing the undo retention or increasing the size of rollbacks. You should also look at the logic involved in the application … Continue reading

Posted in Oracle DBA Interview Questions | Leave a comment

How would you go about increasing the buffer cache hit ratio? | Oracle DBA Questions

Use the buffer cache advisory over a given workload and then query the v$db_cache_advice table. If a change was necessary then I would use the alter system set db_cache_size command.

Posted in Oracle DBA Interview Questions | Leave a comment

How would you go about generating an EXPLAIN plan? | Oracle DBA Questions

Create a plan table with utlxplan.sql. Use the explain plan set statement_id = ‘tst1′ into plan_table for a SQL statement. Look at the explain plan with utlxplp.sql or utlxpls.sql

Posted in Oracle DBA Interview Questions | Leave a comment

What column differentiates the V$ views to the GV$ views and how? | Oracle DBA Questions

The INST_ID column which indicates the instance in a RAC environment the information came from.

Posted in Oracle DBA Interview Questions | Leave a comment

Give the stages of instance startup to a usable state where normal users may access it. | Oracle DBA Questions

STARTUP NOMOUNT – Instance startup. STARTUP MOUNT – The database is mounted. STARTUP OPEN – The database is opened

Posted in Oracle DBA Interview Questions | Leave a comment

What command would you use to create a backup control file? | Oracle DBA Questions

Alter database backup control file to trace.

Posted in Oracle DBA Interview Questions | Leave a comment

Explain the difference between ARCHIVELOG mode and NOARCHIVELOG mode and the benefits and disadvantages to each. | Oracle DBA Questions

ARCHIVELOG mode is a mode that you can put the database in for creating a backup of all transactions that have occurred in the database so that you can recover to any point in time. NOARCHIVELOG mode is basically the … Continue reading

Posted in Oracle DBA Interview Questions | Leave a comment

A table is classified as a parent table and you want to drop and re-create it. How would you do this without affecting the children tables? | Oracle DBA Questions

Disable the foreign key constraint to the parent, drop the table, re-create the table, enable the foreign key constraint.

Posted in Oracle DBA Interview Questions | Leave a comment

Give two examples of referential integrity constraints. | Oracle DBA Questions

A primary key and a foreign key.

Posted in Oracle DBA Interview Questions | Leave a comment

Give the reasoning behind using an index. | Oracle DBA Questions

Faster access to data blocks in a table.

Posted in Oracle DBA Interview Questions | Leave a comment