Database Engine (Recurse Center)
Group of Recurse Center participants creating their own database engine
Run pokedb/command_prompt/poke.py to start a REPL.
SQL processing is in pokedb/command_prompt/processing/
Access management is in pokedb/access/
Transaction management is in pokedb/transactions/
Lock management is in pokedb/locks/
The data layer is in pokedb/storage/
Logging is in pokedb/logs/
pokedb/command_prompt/poke.py will give you a way to input raw SQL and receive responses from the data layer.
There will soon be a daemon process that lives at top-level as well that will listen on socket 1188 for incoming requests to the database.
SQL Processing lives in pokedb/command_prompt/processing/. Current operation runs on sqlparser.py which processes simple SQL statements:
select id1 from pokemon
insert into pokemon (id, val) values (9, \"hey listen\")
select * from pokemon where id=1More robust SQL parser in the works.
The Access Manager is in charge of taking processed read/write commands and performing them. The access/ module contains the BTree structure, which describes where data lives. It communicates with the data layer in pokedb/storage and the lock manager in pokedb/locks.
The Transaction Manager tracks what state all active transactions are in. It maintains this state in-memory. It accepts requests to begin transactions, commit transactions, and rollback transactions from the main process. On commit and rollback, it speaks to the Lock Manager.
The Lock Manager keeps track of what records are locked. It keeps that state in-memory. Depending on which isolation level you are running PokeDB on, the algorithms for acquiring locks changes. The specific algorithms for lock maintenance live in pokedb/locks/isolation.
The Data Layer is responsible for accessing and writing data to/from disk. It contains the buffer pool, copies of data that exist in-memory. It also contains the serializer, which translates data from on-disk format to something the access manager will understand.
The logger is a very thin shell that is something for the Managers to call to log their operations to disk.