Exam AWS Certified Data Analytics - Specialty topic 1 question 68 discussion

For me is CDF

A is not best practice any more. [Quoted]previously Amazon S3 performance guidelines recommended randomizing prefix naming with hashed characters to optimize performance for frequent data retrievals. You no longer have to randomize prefix naming for performance, and can use sequential date-based naming for your prefixes. [Unquoted]

The comment about random strings is also in this useful link: https://docs.aws.amazon.com/whitepapers/latest/s3-optimizing-performance-best-practices/introduction.html

C and F are not doubt easy answers. But I believe A and D both are correct. People quoting randomize prefix not required - are ignoring "sequential date-based naming" which is also not mentioned in question and Athen can run longer as S3 list operations will take time without a well distributed prefix.

CDF: I passed the test

A,C,F Some data lake applications on Amazon S3 scan millions or billions of objects for queries that run over petabytes of data. In this scenario, millions of data points are stored on Amazon S3 and it is recommended to create a random string and add that to the beginning of the object prefixes to increase the read performance for S3 objects.

Correct answers are C, D & F Options C & F as using compression and columnar data format helps improve query performance and optimize storage Option D as using Athena and S3 within the same region would help with query performance and cost. Option A is wrong as S3 scales automatically now and is not bounded by the restriction. Option B is wrong as using the same account does not help in optimizing the cost of query performance. Option E is wrong as using JSON is the same as using CSV files and does help in n optimizing the cost or query performance.

Selected Answer: CDF

Ans A. can't be correct at all. Adding randomized string will make partition size too small to reap the benefits. https://aws.amazon.com/blogs/big-data/top-10-performance-tuning-tips-for-amazon-athena/

C,D,F fulfills are needs

My Answer is C, D & F

For me is CDF

As a best practice, S3 and Athena should be in the same region and account and columnar based is appropriate for the performance. My answer would be BDF

CDF. Parquet compresses by default, yes, but there is also an "uncompressed" option. So C is not redundant.

I think CDF

I goes with C,D,F.

C -> is WRONG in my opinion 1. How do you want to compress Apache Parquet that is already compressed by default? We selected Parquet as file format in F. "For Athena, we recommend using either Apache Parquet or Apache ORC, which compress data by default and are splittable." 2. We still need prefixes but we don't have to randomize them You can increase your read or write performance by parallelizing reads. For example, if you create 10 prefixes in an Amazon S3 bucket to parallelize reads, you could scale your read performance to 55,000 read requests per second. BUT You no longer have to randomize prefix naming for performance and can use sequential date-based naming for your prefixes. 3. You can not reduce data transfer I/O. I/O represents an entity that sends/receives data, therefore, you can only reduce parameters of I/O e.g. data transfer bandwidth, speed, no of operations (e.g. IOPS) etc.