The Foundations of Schema Design in CockroachDB Exam Answers (💯Correct Answers)

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These are the answers to The Foundations of Schema Design in CockroachDB Exam Answers free certification course. These answers have been updated recently and are 100% correct. The final exam is on Monday, April. All answers are 100%.

Q1.When working with the DECIMAL data type, which of the following represents the count of digits to the right of the decimal point?

  • Scale
  • Measure
  • Precision

Q2.In CockroachDB, which of these data types is useful if you need to limit the number of characters stored in a given column?

  • STRING(n)
  • BYTES
  • VARCHAR

Q3:Which data type would be useful if you wanted to store the time of day with an offset from UTC?

  • now()
  • TIME
  • TIMESTAMPTZ

Quiz 2 :

Q1. which feature of CockroachDB helps sort STRING values based on language- and .country-specific rules?

  • STRING(n)
  • GEOGRAPHY
  • Collation

Q2.Which feature of CockroachDB lets the database set the current time rather than requiring the client to set this information?

  • TIMESTAMPTZ
  • TIME
  • now()

Q3.Which data type would be useful if you were looking to store airport locations in North America in latitude and longitude?

  • GEOGRAPHY
  • TIMETZ
  • GEOMETRY

Quiz 3:

Q1.Which of the following would be a good use case for an ARRAY column?

  • You need to store 3-dimensional coordinates for player locations in a game in sub-ARRAYs like so: [ [23, 18, 5], [19, 4, 10], [1, 25, 8] ]
  • You need to store a user’s name as a STRING, age as an INT, and test score as a FLOAT all together in one column
  • You need to store a list of phone numbers associated with a user’s account

Q2.Which of the following would be a good use case for a JSON column?

  • You need to import JSON data from a third party API
  • You want to store a record of every single video game action ever taken by a player in one JSON object
  • You’re storing data from an app and you know all of the fields and data types ahead of time

Q3.What’s one advantage of using an inverted index?

  • They can help avoid the need for full table scans when querying for a matching key: value pair in a JSON column.
  • Inverted indexes are extremely compact, increasing the efficiency of writing to a JSON column.
  • They increase the efficiency of queries that use less than or greater than

What is the purpose of a computed column?

  • They expose data generated from other columns by an expression.
  • They store a homogeneous list of data in every row.
  • They separate each field in a JSON object into a unique index entry.

Quiz 4 : Hash

When should you hash shard an index? Check all that apply.

  • When all candidate index keys are monotonically increasing
  • When you’re using a composite index with a TIMESTAMPTZ column as the second column
  • When you’re running a 3-node cluster but are ready to scale out
  • When there are many null values in the column
  • When the column has only a few possible values (such as a BOOLEAN)

Final assessment :

Q1.You have a table that stores status updates from an autonomous vehicle with the following schema:

moving BOOLEAN,

check_in TIMESTAMPTZ,

status JSON

Here are the first three rows of this table:

moving            |          check_in         |  status

——————+—————————+——————————————-

TRUE              | 2021-07-10 06:19:03-03:00 | ‘{“velocity”: “10”, “heading”: “145.5”}’

TRUE              | 2021-07-10 06:19:07-03:00 | ‘{“velocity”: “12”, “heading”: “147”}

TRUE              | 2021-07-10 06:19:11-03:00 | ‘{“velocity”: “15”, “heading”: “149”}’

Of the following options, what would be the best primary key for this table?

  • Use the status column as the primary key
  • Create a hash sharded primary key with the check_in column
  • Create a compound primary key that includes the status column as the leading column and the check_in column

Q2.When working with the DECIMAL data type, which of the following represents the maximum count of digits both to the left and right of the decimal point?

  • Precision
  • Scale
  • Accuracy
  • (n)

Q3.You have a table that stores a history of alerts received for a monitoring system with the following schema:

alert_code INT,

alert_time TIMESTAMPTZ,

device_id STRING

Here are the first three rows of this table:

alert_code       |        alert_time         |    device_id

—————–+—————————+—————–

404              | 2021-08-26 12:39:35-05:00 | A300-432

502              | 2021-08-26 12:39:46-05:00 | A300-432

404              | 2021-08-26 12:39:48-05:00 | C202-859

Of the following options, what would be the best primary key for this table?

  • Create a compound key with device_id as the leading column and the alert_time column
  • Create a hash sharded primary key with just the alert_time column
  • Create a separate UUID column to use

Q4.You have a 7 node cluster with 1,000,000 rows between 9 tables, one of which has a TIMESTAMP column. How many buckets should the hash sharded index on that column have?

  • 3
  • 5
  • 7
  • 9
  • 11

Q5Which of these is a benefit of using the now() function for a default column value?

  • It can display a TIMESTAMP with more digits than the application
  • It provides accuracy through the implementation of atomic clocks on the cluster
  • It allows the database to be the source of truth for date and time

Q6. What data type or feature of CockroachDB type would be useful if you are looking to display green space in a city as polygons on a city map, which is small enough that you don’t need to worry about the curvature of the Earth?

  • GEOMETRY
  • Collation
  • GEOGRAPHY

Q7. What data type or feature of CockroachDB might you use instead of a definite table schema if you were experimenting with (and frequently revising) a table’s structure during application development?

  • The EXPERIMENTAL flag
  • BYTES
  • JSON

Q8.Which feature of CockroachDB would be helpful if you were building a language learning app and needed a way to sort words from a given language based on the language’s alphabetical sorting rules?

  • STRING
  • Collation
  • GEOGRAPHY
  • VARCHAR

Q9.Which of the following should be avoided (or otherwise mitigated) when choosing an index key with CockroachDB?

  • Letting the database assign UUIDs to a row, which are then used as the primary key
  • Using a compound index key
  • Using the TIMESTAMP data type as the first column of an index

Q10.What is a feature of CockroachDB that you might use if you needed to regularly find purchases less than $100 and the purchase information was stored in a field in a JSON column?

  • Computed Column with a secondary index
  • A regular secondary index on the JSON column
  • Inverted Index

Conclusion

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