Storage

Question 1

What are benefits of columnar vs row based storage?

Answer 1

Columnar is faster when access’s patterns require specific attributes vs entire row access, and example my be averaging or totaling sales. Row level is good when you need to update or read entire entries.

Question 2

What are some examples of columnar storage?

Answer 2

Redshift
Snowflake
Bigquery
Apache Parquet (format)

Question 3

whats map reduce

Answer 3

map reduce is a combination of functions that make parallizing work on a large data set easier.

map formats chunks of the data for processing, and reduce operates on them performing an agegrate operation like sum’ing.

Question 4

what does atomicity mean?

Answer 4

essentially “all or nothing”. considered a set of updates, if it partially completes it would leave the database in an inconsistent state.

Atomicity is on of the parts of ACID.

Question 5

what is ACID in data storage?

Answer 5

Atomic, Consistent (never in an invalid state, transactions move from on valid state to the next without failure), Isolated, concurrent transactions should not create unexpected results. Durable, ones trasnaction is done it should remain through a power outage or system failure.