Explanation:This model requires only a small amount of memory, even for large data sets. 5. Point out the wrong statement :
A. If the output collection does not exist, MongoDB creates and shards the collection on the _id field
B. Map-reduce supports operations on sharded collections, both as an input and as an output
C. mongos dispatches, in parallel, a map-reduce post-processing job to every shard that owns a chunk
D. None of the mentioned
Answer:A
Explanation:This model requires only a small amount of memory, even for large data sets. 5. Point out the wrong statement :
A. If the output collection does not exist, MongoDB creates and shards the collection on the _id field B. Map-reduce supports operations on sharded collections, both as an input and as an output C. mongos dispatches, in parallel, a map-reduce post-processing job to every shard that owns a chunk D. None of the mentioned
Explanation:When using sharded collection as the input for a map-reduce operation, mongos will automatically dispatch the map-reduce job to each shard in parallel. 6. Which of the following function follows the reduce method and modifies the output ?