Research logs

[Junji Zhi]

Paper Summary: XXX

What's cool about it

My doubts

New ideas

[Junji Zhi]

DBMS arch

Block

• Size: 64KB - 128KB today
• Next block: on the same cylinder, followed by adjacent cylinder

Disk space management

• Not common to see DB to talk directly to storage media
• Use File Systems (FS)
• One db file maps to multiple FS files

Page management

• Iteration 1: Header page links to 1) full page, 2) pages with space
  • Problem: Find the next page with 20 byte space
• Iteration 2: Have a header directory: bookkeeping, which page has how much disk space

Relational operators

• SQL: declarative -> Relational operator: imperative.

Note:

• projection operator indicates it is a set, so it removes duplicates in the result

[Junji Zhi]

Paper Summary: Green Marl

What's cool about it

• New graph primitives in a JS like language
• Able to execute Graph algo in parallel

My doubts

• Not my use case
• I just need to find the connection by degrees

New ideas

• How expensive is it to implement Graph + SQL language?

[Junji Zhi]

Paper Summary: Oracle pgql: Property Graph Query Language

https://pgql-lang.org/

• Term: Variable-length graph patterns matching with SQL
• Property graph data model: That's exactly what we were looking for

What's cool about it

SELECT a.number AS a,
       b.number AS b,
       COUNT(e) AS pathLength,
       ARRAY_AGG(e.amount) AS amounts
  FROM MATCH SHORTEST ( (a:Account) -[e:transaction]->* (b:Account) )
 WHERE a.number = 10039 AND b.number = 2090

My doubts

New ideas

• How fast is the parser? How does it execute?
• How does query planner work? How to write one?