Exercises

Exercise 1

1. Create an index in ascending order for the writer field and get the index information. 😀

   {'_id_': {'key': [('_id', 1)], 'ns': 'lab6.blog', 'v': 2},
   'writer_1': {'key': [('writer', 1)], 'ns': 'lab6.blog', 'v': 2}} 

2. Again, print a query plan using executionStats corresponding to the query that finds a writer, Kim.

    "executionStats" : {
   …
                   "executionTimeMillis" : 0,
                   "totalKeysExamined" : 1,
                   "totalDocsExamined" : 1,
                   "nReturned": 1,
                   "executionStages": {
                                 "inputStage": {
                                            "stage": "IXSCAN",
   …

3. Create the compound index on id in descending order and writer in ascending order.

   {'_id_': {'key': [('_id', 1)], 'ns': 'lab6.blog', 'v': 2}, 
   'id_-1_writer_1': {'key': [('id', -1), ('writer', 1)], 'ns': 'lab6.blog', 'v': 2}, 
   'writer_1': {'key': [('writer', 1)], 'ns': 'lab6.blog', 'v': 2}} 

4. Drop all indexes on the blog collection.

   {'_id_': {'key': [('_id', 1)], 'ns': 'lab6.blog', 'v': 2}}

Exercise 2

• Index 생성

  • Create a unique index to doc_id in ascending order

  • Try to build a unique index to line_num

  • Create a sparse index to intersect in ascending order

  • Create a unique and sparse index to intersect_id in ascending order

  • Check the index information

• Compare the results below two cases. (metro collection)

  • Show the first two documents, sorting with doc_id in ascending order.

  • Using intersect index by hint(), show the first two documents

  • Sort doc_id in ascending order

  • Use explain() above each case (executionStats).

  • No Index

     "executionStats" : {
    …
    	 'executionTimeMillis': 155,
    	 'nReturned': 2,
    	 'totalDocsExamined': 186024,
    	 'totalKeysExamined': 0
    	}

  • Indexed

     "executionStats" : {
    …
    	'executionTimeMillis': 21,
    	'nReturned': 2,
    	'totalDocsExamined': 2,
    	'totalKeysExamined': 2
    	}