F2023 #08 - B+Tree Indexes (CMU Intro to Database Systems)

15-445/645 Intro to Database Systems (Fall 2023)
Carnegie Mellon University

[solaris]

this course really defines what's absolute cinema, all the editions which came.

[potapow]

Timestamps
20:27 - B-Tree vs B+Tree
23:03 - B+Tree Insert
26:23 - B+Tree Delete
33:37 - Select conditions
40:50 - Duplicate keys
46:05 - Clustered indexes
50:37 - Node size
52:38 - Variable length keys
55:29 - Intra-node search
59:27 - Optimizations: Prefix compression
1:00:21 - Optimizations: Deduplication
1:01:47 - Optimizations: Suffix truncation
1:02:48 - Optimizations: Pointer swizzling
1:06:07 - Optimizations: Bulk insert
1:08:00 - Write-optimized B+Tree
1:12:43 - Demo (BTree vs Hash index)

[changliu]

How should I delete the leaf node if the key in leaf node is also in some internal nodes?

[blockpaper]

Didn't understand problem with duplicates in tree and how appending record_id solves it. 
Moreover, when I want to delete on 6, how I (DB systems) know what is record_id? I thought point of index is giving you record_id as a value so DB system can fetch tuple using record_id. When we use record_id as a part of a key what is the point of index then?