Multiple Choice Questions - Columnstore Indexes
1. A columnstore index is a technology for storing, retrieving and managing data by using a columnar data format, called a . . . . . . .
A) column segment
2. As an example, if a table has 50 columns and the query only uses 5 of those columns, the columnstore index only fetches the . . . . . columns from disk. It skips reading in the other . . . . . . columns.
A) 5, 45
B) 45, 5
C) 10, 40
D) 40, 10
3. A nonclustered columnstore index and a clustered columnstore index function the same. The difference is a nonclustered index is a secondary index created on a . . . . . . . table, whereas a clustered columnstore index is the primary storage for the . . . . . . . table.
A) columnstore, entire
B) rowstore, entire
C) rowstore, columnstore
D) columnstore, rowstore
4. Columnstore indexes read compressed data from disk, which means fewer bytes of data need to be read into memory.
5. Columnstore indexes give high performance gains . . . . . . . . .
A) for analytic queries that scan large amounts of data, especially on large tables
B) for queries on a small range of values
C) in case of fact tables, since they tend to require full table scans rather than table seeks
D) Both A & C
6. Clustered columnstore indexes collect up to 1,048,576 rows in deltastore before compressing them into the compressed rowgroup. Once the rowgroup contains 1,048,576 rows, the delta rowgroup is marked closed . . . .
A) but it is still available for queries and update/delete operations but the newly inserted rows go into an existing or newly created deltastore rowgroup.
B) and is not available for queries and update/delete operations. The newly inserted rows go into an existing or newly created deltastore rowgroup.
C) and is not available for queries and update/delete operations. The new rows cannot be inserted.
D) but it is still available for queries and update/delete operations but the new rows cannot be inserted.
7. The memory required for creating a columnstore index depends on the . . . . . . .
A) number of columns
B) number of string columns
D) Both A & B
E) All of above
8. If your table has fewer than one million rows, SQL Server will use only one thread to create the columnstore index.
9. By design, a columnstore table . . . . . . . a primary key constraint.
B) does not allow
10. Because data in a columnstore index is grouped by columns, rather than by rows, data can be compressed as efficiently as with rowstore indexes.
1) c, 2) a, 3) b, 4) a, 5) d, 6) a, 7) e, 8) a, 9) b, 10) b