Multi-master replication | EPFL Graph Search

Multi-master replication is a method of database replication which allows data to be stored by a group of computers, and updated by any member of the group. All members are responsive to client data queries. The multi-master replication system is responsible for propagating the data modifications made by each member to the rest of the group and resolving any conflicts that might arise between concurrent changes made by different members. Multi-master replication can be contrasted with primary-replica replication, in which a single member of the group is designated as the "master" for a given piece of data and is the only node allowed to modify that data item. Other members wishing to modify the data item must first contact the master node. Allowing only a single master makes it easier to achieve consistency among the members of the group, but is less flexible than multi-master replication. Multi-master replication can also be contrasted with failover clustering where passive replica servers are replicating the master data in order to prepare for takeover in the event that the master stops functioning. The master is the only server active for client interaction. Often, communication and replication in Multi-master systems are handled via a type of Consensus algorithm, but can also be implemented via custom or proprietary algorithms specific to the software. The primary purposes of multi-master replication are increased availability and faster server response time. Availability: If one master fails, other masters continue to update the database. Distributed Access: Masters can be located in several physical sites, i.e. distributed across the network. Consistency: Most multi-master replication systems are only loosely consistent, i.e. lazy and asynchronous, violating ACID properties. Performance: Eager replication systems are complex and increase communication latency. Integrity: Issues such as conflict resolution can become intractable as the number of nodes involved rises and latency increases.

One-shot Garbage Collection for In-memory OLTP through Temporality-aware Version Storage

Anastasia Ailamaki, Periklis Chrysogelos, Angelos Christos Anadiotis, Syed Mohammad Aunn Raza

Most modern in-memory online transaction processing (OLTP) engines rely on multi-version concurrency control (MVCC) to provide data consistency guarantees in the presence of conflicting data accesses. MVCC improves concurrency by generating a new version o ...

ACM2023

Two-level Data Augmentation for Calibrated Multi-view Detection

Pascal Fua, Martin Pierre Engilberge, Zhiye Wang, Haixin Shi

Data augmentation has proven its usefulness to improve model generalization and performance. While it is commonly applied in computer vision application when it comes to multi-view systems, it is rarely used. Indeed geometric data augmentation can break th ...

2023

Theory-based scaling laws of near and far scrape-off layer widths in single-null L-mode discharges

Paolo Ricci, Holger Reimerdes, Jan Horacek, Cedric Kar-Wai Tsui, Maurizio Giacomin, Adriano Stagni

Theory-based scaling laws of the near and far scrape-off layer (SOL) widths are analytically derived for L-mode diverted tokamak discharges by using a two-fluid model. The near SOL pressure and density decay lengths are obtained by leveraging a balance amo ...

2021