More Interview Questions

Question 1

What is .Q.dpft?

Answer 1

Save table function in the Q namespace.

Question 2

What is Q.hdpf?

Answer 2

Save tables function in the Q namespace.

Question 3

What does exec mean?

Answer 3

returns selected rows and columns from a table.

Question 4

What is each right?

Answer 4

applies a list of paramaters on the right to a single parameter on the left

Question 5

What is each left?

Answer 5

applies a list of paramaters on the left to a single parameter on the right

Question 6

What is each right?

Answer 6

applies a list of parameters on the right to a single parameter on the left

Question 7

What are splayed tables why do we use them?

Answer 7

When a table is too large to fit into memory, we can break it into pieces and save each column individually under a directory with the table name.

Question 8

What are segmented tables why do we use them?

Answer 8

Extension of partitioned databases. The root directory has a sym file and a par.txt file. Data partitions are stored in separate locations.

Question 9

How can you modify on disk data.

Answer 9

using amend ~

Question 10

What is .z.w

Answer 10

handle dictionary.

Question 11

What is .z.p?

Answer 11

loca/UTC timespan.

Question 12

.Q.par?

Answer 12

locate partition

Question 13

What is par.txt?

Answer 13

defines the top-level partitioning of the database into directories. Each row of par.txt is a directory path. Each such directory is itself partitioned in the usual way, typically by date.

Question 14

0h?

Answer 14

mixed list

Question 15

How to delete from namespace?

Answer 15

delete from `.ns

Question 16

What is a window join?

Answer 16

type of as of join.

Question 17

select syntax.

Answer 17

select <return> by <grouping> from <table> where <filter></filter></grouping></return>

Question 18

select 4 columns from a table

Answer 18

select date, sym, open, size from daily

Question 19

How do you select columns and rename them in one line.

Answer 19

select dt: date, stock:sym, open, sz: size from daily

Question 20

How to create a column from a function on an ald column?

Answer 20

select avg: 0.5*high+low from table

Question 21

How to find the sum of a column from a list

Answer 21

select sum column from table

Question 22

How would you find the wavg price of google stock

Answer 22

SELECT vwap:size wavg price
FROM trade
WHERE sym=`GOOG

Question 23

How to find indexes of all Apple stocks

Answer 23

where table[sym] = AAPL

Question 24

how to find the max size of each sym

Answer 24

select max size by sym from table