Database Management Systems

The disk_repair_time parameter in Oracle ASM specifies how long a disk can remain offline before ASM drops it from the disk group. This is a protection mechanism that prevents permanent disk removal during transient failures. It is measured in hours and applies to disks that go offline, not to repair time specification or disk online behavior during faults.

CELL_FLASH_CACHE is a storage clause attribute that controls how database objects are cached in Exadata Smart Flash Cache, overriding the automatic caching policy when compatible parameter is 11.2.0.0 or higher. The attribute accepts three values: NONE (no caching), DEFAULT (uses automatic policy), and KEEP (forces caching). This provides fine-grained control over flash cache usage for specific tables, partitions, or tablespaces.

Predicate evaluation is not offloaded when CELL_OFFLOAD_PROCESSING is FALSE, or when scanning certain table types. Clustered tables and index-organized tables have storage structures that don't support predicate offloading. Fast full scans on compressed indexes also don't support offload. Direct path reads are a different optimization mechanism and don't prevent predicate offloading - they're often used together in Exadata.

Flashback table scans require database-level processing and cannot be offloaded. Queries over 255 columns exceed cell offload capabilities. When CELL_OFFLOAD_DECRYPTION is false on encrypted tablespaces, offload is disabled for security. Option C is redundant - HCC compression doesn't change the 255 column limit. Option E is incorrect - setting CELL_OFFLOAD_DECRYPTION to true enables offload for encrypted data.

Virtual column predicates cannot be offloaded because they require computation. If the tablespace is not fully on Exadata Cell, offload is impossible. Flashback table scans require database-level processing. CREATE INDEX with nosort needs database-side sorting operations that cannot be pushed to storage cells.

SMON (System Monitor) is the Oracle background process responsible for coalescing free extents in dictionary-managed tablespaces, consolidating adjacent free space into larger extents. Process Monitor (PMON) monitors processes, Checkpoint (CKPT) updates checkpoints, and Log Writer (LGWR) writes redo logs.

SQL optimization quality directly determines statement performance - a well-optimized query executes efficiently while a poorly optimized one performs badly regardless of other factors. The optimizer's ability to choose efficient execution plans is more critical than CPUs, parallelism, or index types.

Quality Center supports enterprise databases - Oracle and Microsoft SQL Server. Access is a desktop database, not supported. Sybase is also not a supported QC database (supported are Oracle, SQL Server, and in some versions, MySQL).

DB RACE and ArcSight Intrusion are security monitoring and analysis tools. In Operational Acceptance Testing (OAT), these security tools are predominantly used under the Security Testing service.

Informatica PowerCenter is an ETL tool that can extract data from various heterogeneous sources (like databases, flat files, XML, etc.), transform it, and load it into heterogeneous targets. This flexibility is a key feature that allows integration between different systems and platforms.

In Oracle, the init.ora file (or init.ora) is located in the $ORACLE_HOME/dbs directory on Unix/Linux systems. This is the standard location for instance initialization parameter files.

The Oracle Net configuration files (tnsnames.ora, listener.ora, and sqlnet.ora) are located in $ORACLE_HOME/network/admin directory. This is the standard location for network configuration files.