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14 articles

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Aug 26, 2025 · Databases

6 Proven Strategies to Safely Add Columns to Billion‑Row MySQL Tables

This article explores why adding columns to massive MySQL tables can lock the database, explains the risks, and presents six practical solutions—including native online DDL, downtime maintenance, PT‑OSC, logical migration with dual writes, gh‑ost, and partition sliding windows—along with best‑practice tips for monitoring, backup, and performance.

Large TablesOnline DDLSchema Migration

0 likes · 11 min read

6 Proven Strategies to Safely Add Columns to Billion‑Row MySQL Tables

Aikesheng Open Source Community

Feb 18, 2025 · Databases

Using pt-online-schema-change to Quickly Clean Data and Resolve Disk‑Space Alerts in MySQL

This article explains how to handle MySQL disk‑space alerts by using the pt‑online‑schema‑change (pt‑osc) tool to selectively retain needed rows, migrate data to a temporary table, and drop the original table, thereby achieving fast, low‑impact data cleanup.

Database operationsOnline Schema Changedata cleanup

0 likes · 10 min read

Using pt-online-schema-change to Quickly Clean Data and Resolve Disk‑Space Alerts in MySQL

dbaplus Community

Feb 6, 2025 · Databases

How a MySQL Online Schema Change Platform Evolved from a Single‑Lane Bridge to a Robust 2.0 System

This article recounts the development of ZzoOnlineDDL, a MySQL schema‑change platform, detailing its 1.0 limitations, the 2.0 architectural upgrades, feature set—including intelligent tool selection, timed execution, sharding support, monitoring, and retry mechanisms—and lessons learned from real‑world incidents such as MDL locks, disk pressure, and unique‑index pitfalls.

Online DDLSchema Changegh-ost

0 likes · 34 min read

How a MySQL Online Schema Change Platform Evolved from a Single‑Lane Bridge to a Robust 2.0 System

Aikesheng Open Source Community

Jun 4, 2024 · Databases

Deep Dive into pt-osc: Working Principles, Common Pitfalls, and Practical Recommendations

This article thoroughly explains how the Percona pt-osc tool performs online schema changes in MySQL, analyzes trigger design, deadlock scenarios, data‑consistency issues, and provides detailed test cases, operational tips, and best‑practice recommendations for safe usage.

DDLOnline Schema ChangeTriggers

0 likes · 26 min read

Deep Dive into pt-osc: Working Principles, Common Pitfalls, and Practical Recommendations

Aikesheng Open Source Community

Apr 18, 2023 · Databases

Schema Change for a 400‑Million‑Row MySQL Table Using Cascade Replication

This article details a step‑by‑step strategy for expanding a VARCHAR column from 50 to 500 characters on a 4‑hundred‑million‑row MySQL 8.0 table, evaluating online DDL, gh‑ost, pt‑osc, and ultimately implementing a cascade replication workflow to meet a four‑hour downtime window.

Cascade ReplicationOnline DDLSchema Change

0 likes · 10 min read

Schema Change for a 400‑Million‑Row MySQL Table Using Cascade Replication

Aikesheng Open Source Community

Mar 6, 2023 · Databases

Adding Unique Indexes in MySQL: Methods, Risks, and Hook‑Based Mitigations

This article explains how to add unique indexes to large MySQL tables using Online DDL, pt‑osc, and gh‑ost, compares their advantages and drawbacks, outlines common data‑loss risks, and provides practical hook scripts and best‑practice recommendations to mitigate those risks.

Unique Indexdatabase migrationgh-ost

0 likes · 20 min read

Adding Unique Indexes in MySQL: Methods, Risks, and Hook‑Based Mitigations

Aikesheng Open Source Community

Apr 12, 2022 · Databases

Using pt-osc for Table DDL Changes with DTLE: Procedure and Support

This article explains how DTLE supports pt-osc table schema changes by describing pt-osc's underlying mechanism, DTLE's DDL capabilities, and step‑by‑step instructions for deploying DTLE, preparing MySQL data, configuring a DTLE job, running pt‑online‑schema‑change, and verifying successful synchronization.

DDLDTLEdatabase migration

0 likes · 7 min read

Using pt-osc for Table DDL Changes with DTLE: Procedure and Support

Aikesheng Open Source Community

May 6, 2021 · Databases

Designing an Online DDL Work Order System for MySQL

This article examines the pain points of MySQL DDL operations for large tables, analyzes the limitations of online DDL, compares tools like gh‑ost and pt‑osc, and outlines a comprehensive workflow and implementation details for an automated online DDL work‑order system.

DDLDatabase AdministrationOnlineDDL

0 likes · 9 min read

Designing an Online DDL Work Order System for MySQL

Aikesheng Open Source Community

Sep 16, 2020 · Databases

Online DDL Tool pt-osc: Principles, Usage, and Comparison

This article provides a comprehensive guide to the pt-online-schema-change (pt-osc) tool for MySQL online DDL, covering its underlying mechanism, limitations, installation steps, command‑line syntax, practical examples, and a comparative analysis with native Online DDL and gh‑ost to help users choose the appropriate solution.

Online DDLdatabase migrationmysql

0 likes · 32 min read

Online DDL Tool pt-osc: Principles, Usage, and Comparison

Ctrip Technology

Sep 3, 2020 · Databases

Evolution of Ctrip's MySQL Database Release System: From 1.0 to 3.0

This article details the design, evolution, and operational practices of Ctrip's MySQL database release system, covering its three major versions, the adoption of gh‑ost, safety mechanisms, real‑world case studies, and performance improvements that enable reliable, low‑impact schema changes at scale.

AutomationSchema Migrationdatabase release

0 likes · 14 min read

Evolution of Ctrip's MySQL Database Release System: From 1.0 to 3.0

Aikesheng Open Source Community

Sep 17, 2019 · Databases

Using gh-ost for Online Schema Changes in MySQL: Introduction, Usage, Parameters, and Comparison with pt-osc

This article introduces the gh-ost tool for performing online schema changes on large MySQL tables, explains its architecture and operation modes, provides detailed command‑line parameters and practical examples, and compares its features and performance with the traditional pt‑osc solution.

DDLOnline Schema Changegh-ost

0 likes · 18 min read

Using gh-ost for Online Schema Changes in MySQL: Introduction, Usage, Parameters, and Comparison with pt-osc

JD Retail Technology

Jul 5, 2019 · Databases

Understanding MySQL Online DDL, PT-OSC, and GH-OST for Large Table Schema Changes

This article explains how MySQL performs DDL operations on large tables without long‑lasting locks, covering the evolution from copy‑table and in‑place methods to Fast Index Creation, Online DDL introduced in 5.6, and third‑party tools PT‑OSC and GH‑OST, with detailed process steps and comparisons.

Online DDLSchema Changedatabases

0 likes · 11 min read

Understanding MySQL Online DDL, PT-OSC, and GH-OST for Large Table Schema Changes

Java Backend Technology

Apr 26, 2019 · Databases

What Happens When MySQL Auto‑Increment IDs Exhaust? Practical Solutions

This article explains why MySQL auto‑increment primary keys can reach their limit, shows how switching from INT to BIGINT prevents overflow, and reviews three online schema‑change methods—including native ALTER, pt‑osc, and gh‑ost—plus considerations for triggers, foreign keys, and master‑slave setups.

BIGINTOnline Schema Changeauto_increment

0 likes · 8 min read

What Happens When MySQL Auto‑Increment IDs Exhaust? Practical Solutions

Beike Product & Technology

Apr 13, 2018 · Databases

Understanding MySQL ALTER Operations and Online Schema Change (OSC) Tools

This article explains the detailed steps of MySQL ALTER operations, compares single‑instance and master‑slave scenarios, introduces various online schema‑change tools such as pt‑OSC, outlines native MySQL OSC support, discusses limitations, and provides practical recommendations for safely performing large‑table DDL.

ALTEROnline Schema Changedatabase migration

0 likes · 13 min read

Understanding MySQL ALTER Operations and Online Schema Change (OSC) Tools