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Other Considerations

This section discusses:

Database Monitoring

Activation of the “EnableDBMonitoring” flag, available through the configuration files for the Process Scheduler and the Application Server, allows you to populate context information of the query executed against the database. This is particularly useful when looking for information about the PeopleSoft user running a particular SQL statement.

Example of SQL Statement

The following is an example of SQL statements that will display the context information of a user once “EnableDBMonitoring” is enabled. Modify the scripts according to your needs.

SELECT clientname, clienthostname, clientapplname 
FROM master..sysprocesses 
WHERE spid=spid

If you don’t know the SPID of the user you are trying to monitor, start with the DBID.

Device Management

Try to use separate physical devices for the various servers in your system. Ideally, you should have one device for database data, one device for tempdb, one device for master, one device for syslogs, and one device for the operating system.

Note: Tempdb and transaction logs (syslogs) are used very heavily. PeopleSoft highly recommends using a separate device and allocating adequate space. Mirror the syslogs for recovery.

Caches

Consider using named caches on tempdb and syslogs. Also, consider experimenting with different private log cache sizes as this can improve performance. You can definitely reduce the contention for the last page of syslogs by increasing the size of the Private Log Cache for the users so that they will write to the syslogs table less frequently. Your Database Administrator should determine required memory to support your number of users.

Segments

Consider using segments to separate data, non-clustered indexes, and heavily used tables onto separate devices.

Tempdb

Tempdb is heavily used for sorting (order by statements) and to create worktables for “OR” and “GROUP BY” statements. It is rebuilt every time the dataserver is booted; no permanent data is stored in it. Because of this, the normal considerations for recoverability do not apply to tempdb.

Note: You should consider binding tempdb to its own named cache.

Sizing

Tempdb should be sized according the number of concurrent users, the size of the sorts or group by statements, and the largest possible sort that might be done in tempdb. You will need to consider all databases running on your dataserver because they all share tempdb.

Placement

Whether to place tempdb on a journaled file system, a logical volume, a raw device or a solid-state device is platform-dependent. Following are some considerations for each:

  • Journaled File System

    Placing tempdb on a journaled file system is faster on many platforms because the OS buffers the writes so that Sybase Adaptive Server doesn’t have to wait for physical disk writes. If you have enough OS memory to buffer all of the writes, then tempdb can essentially stay in memory and never have to write to disk.

    When you initialize a file system device(file), Sybase Adaptive Server does not know that there is really enough space in the file system for the size you specify. At run time, the server may well run out of space if the file system was—or became—too full for the tempdb file.

    A precaution would be to configure a separate file system solely for the tempdb file, and set permissions so that only the server can write to this device.

    Note: Do not place user databases on a journaled file system as Adaptive Server cannot guarantee recoverability if the system shuts down abnormally.

  • Raw Device

    There are no special considerations for placing tempdb on a raw device.

  • Solid-State Device

    This is a special device that essentially runs in memory. If tempdb is an I/O bottleneck, then placing tempdb on a solid-state device can improve performance

Another consideration is placing the tempdb syslogs on a separate device.

Network Packet Size

You may be able to improve performance for large result sets by matching the Sybase data packet size to your network packet size and reclaiming unused network bandwidth. Larger packets will also improve network performance by reducing the number of packets sent between the client and server.

From within Configuration Manager, on the Common tab of the Edit Profile dialog box, you can increase the TCP Packet Size for Sybase. Sybase uses a default of 512 bytes and it accepts packet sizes in increments of 512.

The Sybase server must also be configured to accept the larger packet size. To increase the packet size at the server level, issue the following command using Sybase ISQL or a similar SQL utility:

1> sp_configure 'max network packet', 1024
2> go

Note: Increase the network memory allocated per connection using the sp_configuration additional network memory command when increasing the max network packet size.

These server commands will require the Sybase dataserver to be rebooted before the configurations will take effect

Note: PeopleSoft does not recommend increasing the dataserver default network packet size from the default value of 512. This will ensure that all PeopleSoft clients are able to connect. If the TCP Packet Size is increased on the client with Configuration Manager and the max network packet size is not increased on the server, Signon failure will occur.

See also:

  • Sybase Adaptive Server Enterprise Reference Manual

  • Sybase Adaptive Server Enterprise Performance and Tuning Guide

Updating Statistics

When an index gets created, the system gathers statistics about the table. These statistics help to determine the best search method for accessing a table. Each time an index gets created, the statistics are updated for that table. When an index is dropped, the statistics are not removed. In this case you will want to delete the statistics for the dropped index. Use the Sybase DELETE STATISTICS command follow by an UPDATE STATISTICS to rebuild your existing index and column statistics.

You should also update database statistics if there have been significant changes to the index—such as adding or deleting a large number of rows in a table. To do this, use the Sybase UPDATE STATISTICS command. You can run this command against tables and indexes in a database.

Note: There is no command to delete and update statistics for an entire database.