05 - Columnar Databases & Compression (CMU Intro to Database Systems / Fall 2022)

15-445/645 Intro to Database Systems (Fall 2022)
Carnegie Mellon University

[sontungnguyen]

Sound quality is much better in this one compared to previous lectures. Thank you!

[Tryagainbtf]

At 31:20, it is mentioned that nobody uses cubes anymore. The company (ActiveViam) I work at produces an in-memory column store paired with an aggregation engine/data cube, supporting real-time transactions. It is a very niche product, but it does still exist and fill a specific need.
Loving the lecture! Cheers

[Azxsdwrrbh]

Graduated CMU student comes back and listen the newly added lecture.

[foxl]

1:10:50 On incremental encoding: Why does Andy say you don't need to replay the whole thing? If we want to decode the "robbing" word, we have "ing" suffix and and the length of prefix, 4, but to get that prefix we first need to decode "robbed", and so on until we decode all the values up to the word that doesn't have a common prefix with a previous word, in this example it's "rob".

[haitaoyang-gffk]

About the bit-packing algorithm, how does data system know the max value of a column? scan the whole column?

[manmohanmundhraa]

can small tables with say less then 5 column, can replace columner database ?

[olegpatraschku]

at 55:53 and later on I think the id column didn't skip id 5 on purpose ?

[allencheri]

OLTP, row store.
OLAP, column store.

Which store used by HTAP? hybrid store?

[rainwave]

51:50 Someone wasn't paying attention in earlier lectures 😄

[knowsomething-bd]

Are they killing a rat wiz a baseball bat?
It seems like they are.