MC Statement 1: When opting for hard drive back-ups to maintain data availability in case of a calamity, the RPO depends on the underlying infrastructure. Choosing a SAN as storage subsystem might be a solution here, as it keeps the burden of data and backup related traffic from the LAN and from the servers.
Statement 2: Log shipping is a technique which is used for preserving the transaction context of a DBMS in case of a calamity. The remote DBMS used for replication can use the primary log for restoring transactions that were ongoing at the primary site.
Which statements are correct or wrong? Statement 1 is correct, statement 2 is wrong. incorrect Both statements are correct. incorrect Statement 1 is wrong, statement 2 is correct. correct Both statements are wrong. incorrect
MC Given 2 tables R and S. Which of the following join strategies is described by the following algorithm:
denote S -> outer table
for every row s in S do {
for every row r in R do {
if r(a) = s(b) then join r with s and place in output buffer
}
} Sort-Merge join incorrect Nested loop join correct Hash join incorrect None of these joins incorrect
MC Which statement is NOT CORRECT? Using error correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring. correct It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because having multiple physical drives allows for parallel retrieval, which results in much more improved performance. incorrect With bit level data striping, every disk participates in each read or write operation. incorrect It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because reliability can be improved by introducing some measure of data redundancy. incorrect
MC Which statement is CORRECT? Current versions of SQL do not impose any standardization on the internal data model nor on the way in which a relational data model is implemented physically. correct Current versions of SQL require both a specific internal data model AND a specific physical implementation of that data model. incorrect Current versions of SQL require a specific internal data model. incorrect Current versions of SQL impose a specific physical implementation of internal data models. incorrect
MC Which statement is NOT CORRECT? The more attribute types are included in the index, the higher the performance impact is on update queries. incorrect The more selective a query predicate's FF, the less desirable it is to use the index on the corresponding attribute type in the access plan. correct For range queries, a primary or clustered index is more efficient than a secondary index. incorrect The number of block accesses determines the performance, not the number of rows retrieved. incorrect
MC Which statement is CORRECT? Current versions of SQL impose a specific physical implementation of internal data models. incorrect An index can be used to create a physical ordering of rows. correct Compared to SAN, a NAS is much less expensive and much simpler in soft- and hardware. However, it achieves performance similar to a NAS set-up. incorrect Using error correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring. incorrect
MC Which statement is NOT CORRECT? It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because having multiple physical drives allows for parallel retrieval, which results in much more improved performance. incorrect It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because reliability can be improved by introducing some measure of data redundancy. incorrect Using error correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring. correct With bit level data striping, every disk participates in each read or write operation. incorrect
MC Which statement is NOT CORRECT? For range queries, a primary or clustered index is more efficient than a secondary index. incorrect The number of block accesses determines the performance, not the number of rows retrieved. incorrect The more selective a query predicate's FF, the less desirable it is to use the index on the corresponding attribute type in the access plan. correct The more attribute types are included in the index, the higher the performance impact is on update queries. incorrect
MC Which statement is NOT CORRECT? Compared to SAN, a NAS is much less expensive and much simpler in soft- and hardware. However, it achieves performance similar to a NAS set-up. correct To store the same amount of data, RAID 1 needs twice the amount of storage capacity compared to RAID 0. incorrect The management of data storage is more expensive than the purchase of storage hardware, which is why businesses opt for enterprise storage subsystems. incorrect The SCSI I/O command set is a type of block-level I/O protocol which can be exchanged over SCSI, Ethernet or Fibre Channel cabling. incorrect
MC Which statement is NOT CORRECT? A NAS gateway receives file level I/O requests from servers connected to the LAN or WAN and translates these into SCSI block I/O commands to access the external storage devices - this latter connection can be organized by DAS or SAN technology. incorrect A DAS does not offer out-of-the-box capabilities for centralized storage management and sharing unused disk capacity across servers. incorrect Compared to SAN, a NAS is much less expensive and much simpler in soft- and hardware. However, it achieves performance similar to a NAS set-up. correct A SAN is typically best in terms of performance, because it often uses Fibre Channel, the LAN network is freed from storage related traffic, and Fibre Channel compatible storage devices have some onboard intelligence, which allows them to perform certain tasks autonomously, e.g. server-free back-ups. incorrect