All of us have faced ORA-03297 when shrinking a datafile post a cleanup activity. Shrinking a datafile sounds pretty straight-forward but it depends if the purging did reduced the high watermark on the datafile or the high watermark is still at the end of the datafile and you have chunks of free space below the…
During a recent troubleshooting, we came across a requirement where we wanted to know what all locations does Oracle searches tnsnames.ora ? So writing this quick post for the analysis that we did and the results we reached during this exercise. You might already aware of tnsnames.ora in path defined by TNS_ADMIN variable and default…
Below is the query to detect the REDO Log switch frequency for any Oracle Instance:
Cause: The foreground process doing instance recovery died. Action: Check the foreground trace file for the cause of recovery failure.
Cause: A clone database open forces logfile renaming to avoid overwriting the primary logfiles Action Rename the logfiles manually or using the log_file_name_convert initialization parameter
Cause: The specified process did not start. Action: Ensure that the executable image is in the correct place with the correct protections, and that there is enough memory.
Cause: It has been detected that an online log that is being archived has been reused Action: Cannot archive the logfile anymore since it has been overwritten
Cause: The redo block indicated by the accompanying error, is not vaild. It has a checksum that does not match the block contents. Action: Do recovery with a good version of the log or do time based recovery up to the indicated time. If this happens when archiving, archiving of the problem log can be…
Cause: An attempt to switch the current log of a single thread is not allowed because the compatiblity requirements force a new log format version number. When changing log formats, all threads must switch to the new format at the same time. Action: Open the database to cause the coordinated log switch. If that is…
Cause: The file header for the redo log contains a checksum that does not match the value calculated from the file header as read from disk. This means the file header is corrupted Action: Find the correct file and try again.
Oracle Database Internal Mechanism 