Managing Database Settings

The Essbase Kernel uses buffered I/O (input/output) by default, but direct I/O is available on the operating systems and file systems that Essbase supports, with the exception of Linux. See the Oracle Hyperion Enterprise Performance Management System Certification Matrix (http://www.oracle.com/technology/software/products/ias/files/fusion_certification.html).

Buffered I/O uses the file system buffer cache.

Direct I/O bypasses the file system buffer cache and is able to perform asynchronous, overlapped I/Os. The following benefits are provided:

If you set a database to use direct I/O, Essbase attempts to use direct I/O the next time the database is started. If direct I/O is not available on your platform when the database is started, Essbase uses buffered I/O, which is the default. However, Essbase will store the I/O access mode selection in the security file and attempts to use that I/O access mode each time the database is started.

Buffered I/O is the default for all databases.

You may also need to increase the size of some caches. See Sizing Caches.

Index Manager manages the database index and provides a fast way to look up Essbase data blocks. Index Manager determines which portions of the database index to cache in the index cache, and manages the index cache.

Table 150 lists the components that Index Manager controls:

The term index refers to all index files for a single database. The index can span multiple volumes, and multiple index files can reside on a single volume. Use the disk volumes setting to specify disk spanning parameters. For information on setting the index cache size, see Sizing the Index Cache. For information about allocating storage space with the disk volumes setting, see Specifying Disk Volumes.

Allocation Manager, part of the Index Manager, performs these tasks:

When one of these tasks must be performed, the Allocation Manager uses this process to allocate space:

The Allocation Manager allocates space for index and data files based on the database settings for storage.

See Specifying Disk Volumes.

For information on how Essbase stores data, see Storage Allocation.

The Data Block Manager brings data blocks into memory, writes them out to data files, handles data compression, and writes data files to disk. The Data Block Manager controls four components. The following table describes each component:

Table 151 lists the components that Data Block Manager controls:

The size of the data file cache determines how much of the data within the data files can fit into memory simultaneously. The data cache size and the data block size determine how many data blocks can fit into memory simultaneously. Data files for a single database can span multiple volumes; multiple databases can reside on the same volume. See Sizing the Data File Cache and Sizing the Data Cache. Also see Specifying Disk Volumes.

LROs enable you to associate objects, such as flat files, with data cells. Using the Spreadsheet Add-in, users can create and store LRO files, with an .lro extension.

LRO files are stored in the database directory (ARBORPATH/app/appname/dbname; for example, app/Sample/Basic).

Essbase stores information about LROs in an LRO catalog. Each catalog resides in its own Essbase index page and coexists in an index file with other, non-LRO Essbase index pages.

See Linking Objects to Essbase Data and the Oracle Essbase Spreadsheet Add-in User's Guide.

The Lock Manager issues locks on data blocks, which in turn controls concurrent access to data.

The committed access and uncommitted access isolation levels use different locking schemes. For more information on isolation levels and locking, see Ensuring Data Integrity.

The Transaction Manager controls transactions and commit operations and manages database recovery.

Essbase commits data automatically. Commits are triggered by transactions that modify data—data loading, calculating, restructuring, and spreadsheet lock and send operations.

How Essbase commits data depends on whether the transaction isolation level is set to committed or uncommitted access (the default). See Committed Access and Uncommitted Access.

The Transaction Manager maintains a transaction control table, dbname.tct, to track transactions.

For information about commit operations and recovery, see Recovering from a Crashed Database.

Before you change database settings, review information about precedence of the settings as changed in different parts of Essbase, and how Essbase reads those settings:

These methods provide different ways to change the same database settings. In rare cases, you may want to use essbase.cfg to specify settings.

Issue a separate alter database statement for each database setting you want to change. For example, the following MaxL script logs on to Essbase, changes three database settings, and logs off:

login admin identified by secretword;
alter database sample.basic enable committed_mode;
alter database sample.basic set lock_timeout immediate;
alter database sample.basic disable create_blocks;
logout;

You can use MaxL to write batch scripts that automate database setting changes. See the MaxL Language Reference, located in the Oracle Essbase Technical Reference.

For simple items, specify the command, item number representing the parameter, application, database, and value for the parameter:

SETDBSTATEITEM 2 "SAMPLE" "BASIC" "Y";

For parameters that require multiple values, such as Isolation Level (item 18), specify multiple values; in this case, all the values after “BASIC”:

SETDBSTATEITEM 18 "SAMPLE" "BASIC" "1" "Y" "-1";

If you do not know the parameter number, omit it, and Essbase lists all parameters and their corresponding numbers. Essbase also prompts you for a database and an application name.

Use a separate SETDBSTATEITEM command for each parameter; you cannot string parameter numbers together on the same line.

See the Oracle Essbase Technical Reference for information about the parameters for the SETDBSTATE and SETDBSTATEITEM commands.

You can include SETDBSTATEITEM (or SETDBSTATE) in batch scripts. For a comprehensive discussion of batch processing, see Using Script and Batch Files for Batch Processing. For information on specific ESSCMD syntax, see the Oracle Essbase Technical Reference.