Add support for transaction rollback - Githubissues

UWHustle / hustle-in-Rust-now-defunct

Hustle

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Add support for transaction rollback #88

Closed kpgaffney closed 5 years ago

kpgaffney commented 5 years ago

The basic design for making transactions atomic and durable in Hustle is below.

Transaction Log

BEGIN: write a log record to storage that contains the transaction ID and the boolean false to indicate the committed state.
COMMIT: set the corresponding committed state to true.

Inserts

INSERT: create an empty log on storage with the transaction ID in the header. For each row that is inserted, write a log record to storage that contains the block ID and row ID. Then, set the row state to "tentative full".
COMMIT: scan through the log and set each row state to "full". Delete the log.
ROLLBACK or recover: scan through the log and set each row state to "empty". Delete the log.

Deletes

DELETE: create an empty log on storage with the transaction ID in the header. For each row that is deleted, write a log record to storage that contains the block ID and row ID. Then, set the row state to "tentative empty".
COMMIT: scan through the log and set each row state to "empty". Delete the log.
ROLLBACK or recover: scan through the log and set each row state to "full". Delete the log.

Updates

UPDATE: create an empty log on storage with the transaction ID in the header. For each row that is updated, write a log record to storage that contains the block ID, row ID, column ID, and old value. Then, update the row.
COMMIT: delete the log.
ROLLBACK or recover: scan through the log and set each row to the old value.

Action Items

[ ] Develop a log structure backed by stable storage that is optimized for appends.
[ ] Alter the execution operators to write to a log and perform tentative inserts and deletes.
[ ] Implement the functionality described above for BEGIN and COMMIT.

kpgaffney commented 5 years ago

Closing because further discussion is needed.