Hands-on Lab·MySQL
MySQL Table Sizes and Growth
`information_schema` reports table sizes, and `TABLE_ROWS` is an estimate that was wrong every time it was read here. Useful for capacity, useless for counting.
Monitoring and Operations Guide 42 of 45 Beginner
- OSUbuntu 26.04 LTS (resolute)
- MySQL8.4.10-0ubuntu0.26.04.1
- Topologydb-a01 source, db-b01 and db-c01 replicas
- TimeAbout 12 min
- Reviewed27 August 2026
Written against the versions above. InnoDB samples index pages to estimate row counts. The sample size is controlled by `innodb_stats_persistent_sample_pages`, and no setting makes the estimate exact.
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| db-a01 | 192.168.0.81 | Ubuntu 26.04 LTS | Primary / Source / Replica Set Member 1 | 2 Core | 4 GB | 50 GB |
Before you start
- The
appdbdatabase with theeventstable.
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Measure the schema, freshly analysed
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Compare the schema against the disk it lives on