Vadim Yatsenko: Splitting the Read-Only Transaction: Replica Reads Inside an Open Transaction

Read/write splitting is easy for single, autocommit statements. It gets hard the moment a client opens a transaction. Most proxies give up and send every statement inside a transaction to the primary, even the reads. This article is about a middle path we built into Polar Proxy: keep the transaction on the primary, but let its read statements borrow a replica connection.