基本概念

Architecture Overview [DRAFT]

Entity and Concept

Overview

Take standard demo cluster as an example, this cluster consist of four nodes: meta , node-1 , node-2, node-3.

• 节点运行有postgres, pgbouncer, patroni, haproxy, node_exporter, pg_exporter, pgbouncer_exporter,consul等服务
• 集群中有两套数据库集群：pg-meta 与 pg-test。其中pg-test为一主两从结构，pg-meta为单主结构。
• meta节点上运行有基础设施服务：nginx, repo, ntp, dns, consul server/etcd, prometheus, grafana, alertmanager等
• 接入层使用DNS与VIP对外暴露服务，将流量导引至对应的服务节点（可选）。

Service Overview

Pigsty provides multiple ways to connect to database:

• L2: via virtual IP address that are bond to primary instance
• L4: via haproxy load balancer that runs symmetrically on all nodes among cluster
• L7: via DNS (pg-test, primary.pg-test, replica.pg-test)

And multiple ways to route (read-only/read-write) traffic:

• Distinguish primary and replica service by DNS (pg-test, pg-test-primary, pg-test-replica)
• Distinguish primary and replica service by Port (5433 for primary, 5434 for replica)
• Direct instance access
• Smart Client (target_session_attrs=read-write)

Lot’s of configurable parameters items, refer to Proxy Configuration Guide for more detail.

Database Access Guide provides information about how to connect to database.