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  • Concurrency

  • Distributed

    • Talk

      Solving Raft's practical problems in Tarantool. What, how and why

      Language -RU

      Speakers began implementing Raft in Tarantool with somewhat inflated expectations:

      • expected the leader to be persistent, as long as it was alive and connected to most nodes;
      • expected that it would be impossible to get an "I am the leader" message from multiple nodes at the same time;
      • wanted a new leader to show up as quickly as possible if the leader failed;
        wanted to be able to go into "crash mode" where the cluster was writable even after more than half of the nodes had been lost.

      In fact, Raft promises none of these things. And to get it, it is necessary to implement some add-ons, about which we will talk.

    • Talk

      Self-stabilizing Population Protocols

      Language -EN

      Focusing on resources of memory and time, we will discuss how efficiently tasks can be solved when facing transient faults modeled by means of self-stabilization. The talk will give an overview of the related work and focus on several fundamental tasks like counting, naming, and leader election.

    • Talk

      Making a desktop IDE distributed and collaborative

      Language -EN

      In the year 2021, two particular features landed in the IntelliJ family of IDEs. Code With Me gives you the ability to invite and collaborate with others on the same project. Remote development is the feature that allows launching the IDE as a backend on a remote machine or a cloud that users can get access to instead of setting up and developing code locally. While the product-wise and usage differences are clear, they have a lot in common from the IDE synchronization perspective and are created using the same technologies. In this talk, we’ll be exploring the way such synchronization is performed, how one can separate an extremely big and complex system with tons of plugins into several parts; and what it takes to transform a single-user desktop application into a server capable of handling multiple clients.

       

    • Talk

      A sledgehammer to crack a nut: why blockchain is not (always) a good idea

      Language -EN

      In this short talk, we are going to discuss two somewhat provocative claims. First, cryptocurrency, the most popular application of blockchain technology, can be implemented in a much simpler and more efficient way. Second, the permissionless setting with mutual distrust, assumed by conventional blockchain implementations, is way too pessimistic in most cases. We then show how the two observations can help in designing efficient and robust replicated services.

    • Talk

      Scaling Raft

      Language -EN

      In this talk, Konstantin will discuss the challenges of supporting hundreds of instances of the Raft protocol on a single node and how we were able to significantly reduce the static burden on the network and disk each Raft group creates by sharing the work of failure detection and persistence between multiple groups.

    • Talk

      Distributed transactions implementation trade-offs

      Room 2
      Language -RU

      This is educational first speech. Let's see why ACID transaction properties are important and how they are implemented in distributed databases with sharding and replication. What about geo-distributed databases? Is it possible to achieve fault tolerance (high availability) and support strong consistency in such databases. What are trade offs for performance. discuss famous CAP theorem and what it means for data indexing and DB transactions.

       

    • Talk

      Parallel Asynchronous Replication between YDB Database Instances

      Room 2
      Language -RU

      Asynchronous replication is a well-known technique to provide an independent replica of a database for different purposes including disaster recovery, geo-replication or scaling read workload. Traditionally, a log of changes from source replica is treated as an input for target replica database. If source and target replicas are distributed databases that handle high workload, putting all updates to a single log of changes could be nearly impossible. 

  • Database Internals

    • Talk

      How ScyllaDB makes LSM-tree compaction state-of-art by leveraging RUM conjecture and controller theory

      Language -EN

      LSM-tree storage engines are known for providing very fast write throughput, as they allow new data to be flushed into immutable files called Sorted String Table, a.k.a. SSTable. But there's no such thing as a free lunch. This append-only nature of the LSM tree generates read amplification over time, because a given key can be redundantly stored across multiple immutable files. That's the reason storage engines have to employ a background compaction process, to reduce both read and space amplification.

    • Discussion

      Roundtable: Cloud Databases as a Service

      Language -RU

      Roundtable on moving databases to the cloud. We will discuss different approaches and experiences, economic component and development.

      • Oleg Anastasyev
      • Vladimir Ozerov
      • Ivan Prisyazhniy

    • Talk

      HTAP Workloads: Challenges and Solutions

      Language -EN

      In this talk, we consider challenges posed to modern DMBS by so-called HTAP workloads. HTAP (Hybrid Transactional & Analytical Processing) combines:

      1. Fast OLTP-style requests that should be executed with maximal throughput and reasonably low latency.
      2. OLAP-style analytical queries that require reading a lot of rows to be executed.

      As a solution to this question, we consider several approaches: persistent-parallel trees, fork+COW approach (from HyPer), MVCC, and HTAP-aware LSM tree (from LASER).

    • Talk

      OK S3

      Room 2
      Language -RU

      Vadim will describe implementation of S3 compatible storage service based on blob and NewSQL storages at Odnoklassniki. The talk will cover the architecture and data model, features and trade-offs, performance and optimization, some intricacies and surprises. The ideas and experience presented in the talk might be useful to designers and developers of distributed storage services, especially S3-compatible and/or Cassandra-based ones.