This TechNote answers frequently asked questions about Sybase SQL Server and Adaptive Server Enterprise dumps and loads.
This document answers frequently asked questions about database dump and loads with Adaptive Server Enterprise and Sybase SQL Server 11.0.x. It comprises the following sections:
Logs
Dumps and Loads
Backups and Maintenance
Logs
What information is tracked by the logptr column in master..sysdatabases?
The logptr column points to the first data page in the transaction log. This column is necessary for the dump tran with no_truncate command to function.
If the transaction log is kept on a separate physical device, you can use the dump tran with no_truncate command to dump the current transaction log even if the database itself has become inaccessible. This feature lets you rebuild a database to its state at the moment it was lost due to media failure.
WARNING! Do not use the dump tran with no_truncate command with a database that is in use. For more information, see the Sybase Adaptive ServerTM Enterprise System Administration Guide.
Media recovery from the current log is possible because the logptr column is located outside the user database, in the master database.
Why does my log grow during dump, even with trunc log on chkpt option?
A database is configured to have trunc log on chkpt. During a dump of that database, the syslogs table continues to grow until the dump is finished. Why doesn't the log truncate?
The log cannot truncate because the checkpoint process occurs only at the start and at the completion of the database dump.
Dumps and Loads
What effect does select into/bulkcopy have on dump transaction?
Why are dump transaction commands not allowed for a database when it has the select into/bulkcopy option set? Trying to do so generates Error 4207.
This happens only when a minimally logged operation occurred and the select into/bulkcopy option is set. When the select into/bulkcopy option is set in a database, rows added with fast bulkcopy are not logged. Only the space allocated during the fast bulkcopy is logged. The transaction log is not complete and could not be used for load transaction.
To perform a dump transaction for that database, the following must be true:
select into/bulkcopy option must be disabled with sp_dboption.
The database must be dumped with dump database before you dump the transaction log.
See the Sybase Adaptive ServerTM Enterprise Reference Manual and the Sybase Adaptive ServerTM Enterprise System Administration Guide for details.
What is the effect of a database's growth on dump database time?
As the number of pages used by a database increases, does the time for a dump increase because the dump database command has to check all the pages in that database or does it remain constant?
The time required for dumping a database increases as the number of pages increases. The dump process dumps only the allocated pages being used in that database. The dump does not need to check every page, only the allocated pages.
What are the differences between dump transaction and dump transaction with no_truncate?
When a dump transaction command is issued, the server makes a copy of all the inactive transactions that occurred on a particular database up to the point of the actual time of dump, and those transactions are removed from the log. When thedump transaction with no_truncate command is issued, the server makes a copy of the inactive transactions but does not remove those transactions from the log.
Therefore, if successive transaction log dumps are performed using dump transaction with no_truncate, the log will grow in size and will eventually have to be purged either via dump transaction or dump transaction with truncate_only.
Note: The dump transaction with truncate_only command does not make a copy of the log, but purges the log of all inactive transactions.
What are the differences between dump transaction with truncate_only and dump transaction with no_log?
Neither dump transaction with truncate_only nor dump transaction with no_log make a copy of the log records. Both reduce the space used in syslogs whenever possible.
The dump transaction command adds checkpoint records and log-deallocation records to the log even when just truncating the log, except when using the with no_log option. Use dump transaction with no_log only when dump transaction with truncate_only fails because syslogs lacks room for dump transaction's checkpoint and deallocation records. See dump transaction in the Sybase Adaptive ServerTM Enterprise System Administration Guide.
WARNING! You must dump the database immediately after performing either of these options. If corruption occurs while using dump transaction with no_log or dump transaction with truncate_only, you will be unable to recover because there will be no log information.
Will databases retain dbid value with dump and load?
A database is dumped from one server and loaded onto another. Will that database have the same dbid after the load?
No, because the dbid of a database is determined at the time the database is created and a row is added to sysdatabases. The dbid of the database that is loaded is the dbid of the database into which it is loaded.
Why does suid change in a database being loaded to match sysdatabases?
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