Appendix B. Glossary
This is a list of terms and their meaning in the context of Shardman. For terms that are used in this document in the general context of PostgreSQL and relational databases, see PostgreSQL Glossary.
- ACID
Atomicity, Consistency, Isolation and Durability. This set of properties of database transactions is intended to guarantee validity in concurrent operation and even in event of errors, power failures, etc. For more information, see PostgreSQL Glossary.
- Clover
A set of nodes where each node holds a PostgreSQL instance that is the master for one of the replication groups and PostgreSQL instances that are replicas for all the other replication groups. The total number of nodes in a clover is equal to the replication factor.
- etcd
A distributed reliable key-value store for the most critical data of a distributed system. For more information, see etcd home page.
- Global role
A role such that operations on it are always performed on all replication groups simultaneously.
- Global user
A user such that operations on it are always performed on all replication groups simultaneously.
- Replication group
A stolon cluster with one master and one or more replicas. Replication groups are organized in Clovers. Shardman utilities often refer to replication groups as "repgroups".
- Shard
In Sharding, some table partitions located on one node being the master for them.
- Sharded table
A partitioned table where some partitions are regular local tables that make up a Shard and the other partitions are foreign tables available from remote servers via
postgres_fdw.- Sharding
A database design principle where rows of a table are held separately in different databases that are potentially managed by different DBMS instances.
- Silk (Shardman InterLinK)
Experimental transport that can be used in a Shardman cluster for communication between nodes.
- stolon
A cloud native PostgreSQL manager for PostgreSQL high availability. For more information, see stolon on github.
- syncpoint
A set of consistent LSNs in a cluster corresponding to a global snapshot.