MC Which statement is CORRECT? 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 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 do not impose any standardization on the internal data model nor on the way in which a relational data model is implemented physically. correct MC Which statement is NOT CORRECT? Index creation can help improve the performance of join queries. incorrect Indexing makes it harder to enforce uniqueness on a (combination of) column(s). correct An index implies a logical ordering of the rows in a table. incorrect An index can be used to create a physical ordering of rows. incorrect MC Which statement is NOT CORRECT? 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 The more attribute types are included in the index, the higher the performance impact is on update queries. 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
  }
} Hash join incorrect Sort-Merge join incorrect Nested loop join correct None of these joins incorrect MC Given 2 tables R and S. Which of the following join strategies is described by the following algorithm:

Stage 1:
sort R according to r(a)
sort S according to s(b)

Stage 2:
retrieve the first row r of R
retrieve the first row s of S
for every row r in R do {
  while s(b) < r(a) do {
    read the newt row s of S
    if r(a) = s(b) then join r with s and place in output buffer
  }
} Hash join incorrect Sort-Merge join correct Nested loop join incorrect None of these join strategies incorrect MC Which statement is CORRECT? SQL is a declarative language, meaning that the programmer has to specify what data to retrieve and how the data is to be located and retrieved from the physical database files. incorrect The filter factor of a predicate is the fraction of rows that contain a missing value for that predicate. incorrect If no further statistical information about a predicate is available, the filter factor of that predicate can be estimated by dividing 1 by the number of different values the attribute type can have. correct Table cardinality is another way of referring to the number of columns in a table. incorrect MC Which statement is NOT CORRECT? RAID level 0 is used if performance is more important than fault tolerance. incorrect To store the same amount of data, RAID 1 needs twice the amount of storage capacity compared to RAID 0. incorrect RAID level 5 strikes a balance between read and write performance, storage efficiency, and fault tolerance. incorrect Block level striping as used in RAID 0 does not increase read performance. correct 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 With bit level data striping, every disk participates in each read or write operation. incorrect Using error correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring. correct MC Which statement is NOT CORRECT? The management of data storage is more expensive than the purchase of storage hardware, which is why businesses opt for enterprise storage subsystems. incorrect 'Network attach' refers to establishing a many-to-many connection between storage devices and the corresponding servers by means of network technology. incorrect Although SCSI has been a popular medium for connecting storage devices to servers and/or processors in the past, nowadays, it is not used anymore for high performance and high capacity workstations and servers. correct 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 DAS does not offer out-of-the-box capabilities for centralized storage management and sharing unused disk capacity across servers. incorrect 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 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 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 MC Which statement is NOT CORRECT? A primary element of a contingency plan is the quantification of recovery objectives in RTO and RPO, given the organization's strategic priorities. incorrect The only points of failure of a database system are the availability of database functionality and the availability of the data itself. correct The manual failover of DBMS functionality is a simple and not very expensive solution to guarantee the availability of DBMS functionality in case of a calamity. incorrect Rolling upgrades are an example of how to avoid downtime in a cluster computing set-up. incorrect 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? Both statements are correct. incorrect Statement 1 is correct, statement 2 is wrong. incorrect Statement 1 is wrong, statement 2 is correct. correct Both statements are wrong. incorrect