Upgrade from 8.4 to 9.7 overview¶

Topic type: Concept

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Need expert guidance for your upgrade? Percona Support can assist .

Why upgrade to Percona Server for MySQL 9.7?¶

Moving from 8.4 Long-Term Support (LTS) to 9.7 is more than a version bump. Updated defaults, deprecated options, and behavior changes can affect performance and break existing scripts. Treat the upgrade as a project. Plan the steps, select a method that fits your downtime window, and verify the result.

Identify the benefits of upgrading¶

The following table lists the main benefits.

Benefit	What it means for you
Security fixes	Patches close known vulnerabilities and protect data from attacks.
Additional features	Improved performance, reliability, and capability.
Less manual effort	Automation handles routine tasks without hands-on intervention.
Lower operational cost	Improved efficiency and scalability reduce day-to-day operations cost.

Assess the risks of staying on an older version¶

The following table summarizes the risks.

Risk	Potential impact
Security exposure	Without recent patches, attackers can breach, corrupt, or destroy data.
Feature stagnation	Missing capabilities slow performance and increase outage frequency.
Reduced support	Older versions receive less vendor assistance, which lengthens troubleshooting.
Compatibility problems	Hardware, operating system releases, or third-party applications may not work with an outdated server.
Unplanned upgrade pressure	Hardware or operating system failures can force a rushed upgrade and increase error risk.

Concerned about these risks? Percona Support can help assess and mitigate them .

Understand what the upgrade process changes¶

A 9.7 restart against an existing data directory runs an automatic two-phase upgrade. The phases run inside the server with no user action required. The split lets the server start with a current data dictionary even when other tasks remain.

Phase	Scope	What the server does
Data dictionary upgrade	The data dictionary tables in the `mysql` schema, the Performance Schema, and the `INFORMATION_SCHEMA`	Creates dictionary tables with current definitions, copies metadata across, and atomically replaces the prior tables
Server upgrade	The system tables in `mysql`, the `sys` schema, and all user schemas	Runs `CHECK TABLE ... FOR UPGRADE` on each table, repairs as needed, and stamps each table with the 9.7 version number

The data dictionary upgrade always runs first. The server tracks two versions in the data dictionary: the data dictionary version and the server (MySQL) version. The server upgrades any part that lags the 9.7 expected versions.

The --upgrade server option controls the automatic upgrade behavior at startup.

Mode	Behavior
`AUTO` (default)	Run any out-of-date upgrade tasks across both phases
`NONE`	Skip both phases. The server exits with an error if the data dictionary requires an upgrade
`MINIMAL`	Run the data dictionary upgrade only. Group Replication cannot start after a MINIMAL upgrade because system tables remain stale
`FORCE`	Run the data dictionary upgrade, then force the server upgrade across every schema. Use the mode to re-create missing system tables, such as help tables or time zone tables. Expect a longer startup

The server upgrade locks each table during processing. Plan a maintenance window that fits the largest tables in the schema. Time zone tables are not refreshed automatically. Reload the tables with mysql_tzinfo_to_sql if your applications depend on time zone names.

For underlying MySQL guidance, see What the MySQL Upgrade Process Upgrades .

Run the upgrade workflow¶

The following steps describe the upgrade workflow from 8.4 to 9.7.

Step 1: Review what changed¶

Review the following resources to understand behavior changes, removed features, and toolkit impacts:

Percona Toolkit updates for 9.7 describes toolkit changes
MySQL upgrade paths and supported methods confirms supported upgrade paths
Keywords and Reserved Words in MySQL 9.7 lists reserved words that break unquoted identifiers

Step 2: Complete pre-upgrade preparation¶

Work through the pre-upgrade checks in the upgrade checklist. The pre-upgrade checks cover the following topics:

Authentication methods and client compatibility
Backup and restore procedures
Configuration defaults
Plugin-to-component transitions, if applicable
Removed features and variables
Replication script updates (MASTER/SLAVE to SOURCE/REPLICA syntax)

Step 3: Choose your upgrade strategy¶

Select an upgrade method that fits your environment:

MySQL upgrade paths and supported methods confirms supported upgrade paths
Upgrade strategies covers in-place, logical dump and restore, side-by-side, MySQL Clone, and rolling-replication methods

Step 4: Run the upgrade¶

Follow the procedures in Upgrade procedures for 9.7. The procedures cover repository-based and standalone package upgrades.

Step 5: Validate the upgrade¶

Complete the post-upgrade validation in the upgrade checklist. The validation steps cover the following topics:

Backup and recovery testing
Connectivity and authentication
Logs and metrics
Performance baselines
Replication health, if applicable
Spatial index re-creation

Reduce upgrade risk¶

The following tools help reduce upgrade risk before you run the production upgrade:

A full dry-run workflow exercises every step. Create a backup, restore on 9.7, run smoke and load tests, validate, and practice rollback.
Percona XtraBackup creates hot backups for restore testing.
pt-upgrade compares query plans between Percona Server 8.4 and 9.7.

These tools surface regressions early and confirm a reliable fallback plan.

Test before production¶

Configure a sandbox and run the upgrade there first. The sandbox is essential for a successful migration.

Data loss risk

Percona Server for MySQL 9.7 does not provide a supported in-place downgrade to an earlier major version. Plan the rollback path before the upgrade. The most reliable rollback is to restore a backup taken before the upgrade. Logical dump and load, or replication into the older version, are also supported.

Operations in 9.7 can change data formats, which breaks binary compatibility with older versions. The safest approach is to provision a fresh server on the older version and reload your data. Do not expect a one-step undo of the upgrade. See Downgrade options for more details.

We recommend upgrading to the most recent LTS release for security, performance, and full support.

Need personalized support during your upgrade? Contact Percona Support for a detailed migration plan .