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Top Architect
Top Architect
Dec 3, 2025 · Backend Development

How to Add a Column to a Billion‑Row Order Table Without Breaking Production

When a new business field is required on a core order table with tens of millions of rows, the article walks through the risks of direct ALTER TABLE, evaluates master‑slave switching, online DDL tools, extension tables, JSON‑based schema‑less designs, and a clever reuse of an existing redundant column, providing practical steps and performance insights.

ALTER TABLEJSON columnOnline DDL
0 likes · 9 min read
How to Add a Column to a Billion‑Row Order Table Without Breaking Production
Aikesheng Open Source Community
Aikesheng Open Source Community
Jun 24, 2025 · Databases

Why MySQL 8.0 Table Rebuilds Slow Down and How to Fix It

MySQL 8.0 (especially versions 8.0.20+) suffers a performance regression in table‑rebuilding operations like ALTER TABLE … FORCE, running up to three times slower than 5.7 due to the default innodb_doublewrite_pages setting, but the issue can be mitigated by adjusting the parameter or upgrading to 8.4+.

ALTER TABLEDatabase TuningPerformance Regression
0 likes · 4 min read
Why MySQL 8.0 Table Rebuilds Slow Down and How to Fix It
Aikesheng Open Source Community
Aikesheng Open Source Community
Jan 30, 2024 · Databases

Troubleshooting VARCHAR Column Expansion Issues with MySQL Online DDL

This article analyzes why ALTER TABLE operations that extend VARCHAR columns sometimes fail in MySQL, explains the underlying Online DDL constraints, presents several real‑world problems such as default‑value handling, indexed columns, and hidden table‑rebuild quirks, and offers practical solutions for each case.

ALTER TABLEDatabase AdministrationOnline DDL
0 likes · 17 min read
Troubleshooting VARCHAR Column Expansion Issues with MySQL Online DDL
Top Architect
Top Architect
Dec 5, 2021 · Databases

Why MySQL Table Size Does Not Decrease After DELETE and How to Reduce It

This article explains why deleting rows in MySQL does not shrink the underlying table file, describes the InnoDB storage mechanics that cause this behavior, and provides practical solutions such as OPTIMIZE TABLE, ALTER TABLE, and Online DDL to reclaim space and avoid table‑locking issues.

ALTER TABLEDELETEInnoDB
0 likes · 8 min read
Why MySQL Table Size Does Not Decrease After DELETE and How to Reduce It
Top Architect
Top Architect
Jul 19, 2021 · Databases

Why MySQL DELETE Does Not Reduce Table File Size and How to Shrink It

The article explains why deleting rows in MySQL does not shrink the physical table file, describes the underlying InnoDB storage mechanisms, and provides practical methods such as OPTIMIZE TABLE, ALTER TABLE, and Online DDL to reclaim space and reorganize the table.

ALTER TABLEDELETEDatabase Maintenance
0 likes · 7 min read
Why MySQL DELETE Does Not Reduce Table File Size and How to Shrink It
ITPUB
ITPUB
Feb 24, 2017 · Databases

Why Adding NOT NULL Columns Can Still Store NULLs in Oracle?

This article examines the surprising behavior of Oracle when adding NOT NULL columns with default NULL values, explains how different Oracle versions handle the constraint, demonstrates test cases, and clarifies the underlying data‑dictionary mechanism that leads to unexpected query results.

ALTER TABLENOT NULLOracle
0 likes · 7 min read
Why Adding NOT NULL Columns Can Still Store NULLs in Oracle?
ITPUB
ITPUB
Apr 29, 2016 · Databases

How to Clean Up MySQL Table Fragmentation with OPTIMIZE and ALTER

This guide explains why MySQL tables become fragmented, how to detect fragmentation using information_schema queries, and how to defragment tables safely with OPTIMIZE, ALTER TABLE, or MySQL startup options while noting engine‑specific behavior and best‑practice cautions.

ALTER TABLEInnoDBMyISAM
0 likes · 5 min read
How to Clean Up MySQL Table Fragmentation with OPTIMIZE and ALTER
MaGe Linux Operations
MaGe Linux Operations
Jan 12, 2015 · Databases

Why Does ALTER TABLE Hang? Understanding MySQL Metadata Locks

This article explains why ALTER TABLE statements can become blocked by MySQL’s metadata locking, describes the underlying mechanisms, outlines common scenarios that cause “Waiting for table metadata lock,” and offers practical steps to diagnose and avoid such lock contention.

ALTER TABLEmetadata lockmysql
0 likes · 8 min read
Why Does ALTER TABLE Hang? Understanding MySQL Metadata Locks