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
}
} Nested loop join correct Sort-Merge join incorrect Hash join incorrect None of these joins 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 Nested loop join correct None of these joins incorrect Sort-Merge join incorrect
MC Which statement is NOT 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 Current versions of SQL require a specific internal data model. correct Index creation can help improve the performance of join queries. incorrect
MC Which statement is NOT CORRECT? Rolling upgrades are an example of how to avoid downtime in a cluster computing set-up. incorrect 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 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
MC Which statement is NOT 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 Indexing makes it harder to enforce uniqueness on a (combination of) column(s). correct Index creation can help improve the performance of join queries. incorrect
MC Which statement is CORRECT? Current versions of SQL require a specific internal data model. incorrect Using error correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring. 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. incorrect RAID level 5 strikes a balance between read and write performance, storage efficiency, and fault tolerance. correct
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 None of these join strategies incorrect Sort-Merge join correct Nested loop join incorrect
MC Which statement is NOT 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 A primary element of a contingency plan is the quantification of recovery objectives in RTO and RPO, given the organization's strategic priorities. incorrect Rolling upgrades are an example of how to avoid downtime in a cluster computing set-up. incorrect The only points of failure of a database system are the availability of database functionality and the availability of the data itself. correct
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 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 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
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 Nested loop join incorrect None of these join strategies incorrect Sort-Merge join correct