# Read Consistency with Database Replicas

DevFeed: [Read Consistency with Database Replicas](<https://devfeed.tech/articles/read-consistency-with-database-replicas-1539.md>)

Original publisher: [Read original article](<https://shopify.engineering/read-consistency-database-replicas>)

Author: Thomas Saunders

Published: 2021-02-22T21:55:03Z

Content type: article

Language: en

Sources: [Shopify Engineering](<https://devfeed.tech/sources/shopify-engineering.md>), [Shopify Engineering - Shopify Engineering](<https://devfeed.tech/sources/shopify-engineering-shopify-engineering.md>)

Topics: [Replication](<https://devfeed.tech/topics/replication.md>), [Database](<https://devfeed.tech/topics/database.md>), [Shopify](<https://devfeed.tech/topics/shopify.md>), [data](<https://devfeed.tech/topics/data.md>), [User Experience](<https://devfeed.tech/topics/user-experience.md>)

Tags: [database](<https://devfeed.tech/tags/database.md>), [performance](<https://devfeed.tech/tags/performance.md>), [recovery](<https://devfeed.tech/tags/recovery.md>), [replication](<https://devfeed.tech/tags/replication.md>), [server](<https://devfeed.tech/tags/server.md>), [shopify](<https://devfeed.tech/tags/shopify.md>)

## AI overview

Shopify examines database replicas as read-only data sources for read-heavy applications. The article explains how replication lag can produce stale or inconsistent results across multiple queries, compares tight consistency with GTID-based causal consistency, and introduces the solution selected by Shopify's Database Connection Management team.

## Source excerpt

At Shopify, we've long used database replication for redundancy and failure recovery, but only fairly recently started to explore the potential of replicas as an alternative read-only data source for applications.