Crowdly

Immediate execution

No execution

Parallel execution only

Which operation is lazy evaluated in Pandas?

df.groupby()

df.head()

60%

df.describe()

None (Pandas is eager by default)

If many pairs hash to the same bucket in PCY, what is the consequence?

Algorithm fails

No impact

False positives increase

False negatives increase

CURE selects representative points by:

Choosing centroids

50%

Using medians

Selecting well-scattered points and shrinking them

50%

Random sampling only

Which is a key difference between ETL and ELT?

Storage type

Programming language

Data format

Order of transformation and loading

In PCY, the bitmap size depends o

Number of buckets

Number of transactions

Number of items

Support threshold

What is the result of this operation?

df['col'].fillna(method='ffill')

Replace nulls with previous value

Replace nulls with mean

Remove null rows

Replace nulls with 0

60%

While uploading a file to HDFS using -put, what happens if the destination path already contains a file with the same name?

The file is appended

The file is overwritten silently

83%

The file is renamed automatically

The command fails unless -f is used

17%

Which MapReduce phase is primarily responsible for implementing a JOIN operation?

Input Split

Combiner

80%

Mapper

Shuffle and Sort

If a dataset is unevenly partitioned, SON may:

Generate more candidates

Reduce accuracy

33%

Miss frequent itemsets

67%

Fail completely