Microsoft SQL Server 2005 Reporting Services

SQL Server reporting services (subsequently SSRS) default install databases are:-

Database	Description
ReportServer	Report Server database is a SQL Server database that stores part of SSRS configuration, report definitions, report metadata, report history, cache policy, snapshots, resources, security settings, encrypted data, scheduling and delivery data, extension information and report execution log information. Note: Although users can certainly directly access databases in the SSRS catalog and directly modify objects that SSRS uses, this is not a recommended (or supported) practice. Underlying data and structures within the SSRS catalog are not guaranteed to be compatible between different releases of SSRS, service packs, or patches.
ReportServerTempDB	This database is responsible for storing intermediate processing products, such as cached reports (to increase performance), and session and execution data. Note To store temporary snapshots in the file system, instead of the database, administrators should complete the following steps. First modify RSReportServer.config and set WebServiceUseFileShareStorage and WindowsServiceUseFileShareStorage to True. Then set FileShareStorageLocation to a fully qualified path. The default path is C:\Program Files\Microsoft SQL Server\MSSQL.3\Reporting Services\RSTempFiles. Unlike SQL Server's tempdb, data in ReportServerTempDB survives SQL Server and Report Server restarts. Report Server periodically cleans expired and orphan data in ReportServerTempDB. All data in ReportServerTempDB can be deleted at any time with minimal or no impact. The minimal impact that a user might experience, for example, is a temporary performance reduction due to lost cache data and a loss of an execution state. The execution state is stored in the table SessionData. Loss of the execution state results in an error: "Execution 'j4j3vfblcanzv3qzcqhvml55' cannot be found (rsExecutionNotFound)." To resolve the loss of the execution state, a user would need to reopen a report. TIP SSRS does not recover deleted ReportServerTempDB or tables within this database. To quickly recover from erroneous deletions of objects in this database, keep a script or a backup of an empty ReportServerTempDB handy.
RSExecutionLog	Additionally, the RSExecutionLog database can be added after the initial installation. This database stores additional logging information.