Describe Tarantool features in common DBMS terms

[ligurio]

Tarantool is a complex system that stores user data.
I think users want to know guarantees that Tarantool provides before start to use it. Unfortunately we don't have any description of tarantool guarantees in common DBMS terms, like 'consistency model', 'transation isolation level', 'ACID/BASE', 'MVCC' etc.

I've tried to search this in documentation and failed.

What isolation levels tarantool uses? Search in documentation found only two relevant pages: Transaction control and SQL. Both pages doesn't contain answers for the question. On page about SQL: "SET TRANSACTION statement ISOLATION SERIALIZABLE clause | SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; | Fail. Syntax error.". Well, but what isolation levels are supported then?

Transaction control describes atomicity support and isolation. What about durability and consistency?

This page contains good description of possible consistency models.

Also it's worth to mention that we don't support transaction for DDL.

Examples:

• DGraph
• CockroachDB
• FaunaDB
• YugaByte
• MongoDB, https://www.mongodb.com/transactions
• Aerospike: https://www.aerospike.com/docs/architecture/acid.html and https://www.aerospike.com/docs/architecture/consistency.html

[ligurio]

@lenkis What kind of feedback do you need?

[pgulutzan]

I think this refers to the situation that existed before version 2.6.1 when memtx_use_mvcc_engine arrived.
Before that we could say "serializable" because everything really was serialized.
Now it is not necessarily so, and the manual does mention snapshot and serializable, e.g. here:
https://www.tarantool.io/en/doc/latest/book/box/atomic/#transactional-manager
I regret that I think there might some flaws related to that claim, e.g. here
tarantool/tarantool#5801

[Totktonada]

Now we're going deeper: #2793.