MySQL Collation Repair: Column Level Encoding Issues

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This document is part of the guide on How to Fix the Collation and Character Set of a MySQL Database. Please refer to that page for more information.

Table of Contents

Before Proceeding

Before proceeding, ensure that you:

  • Have shut down Confluence
  • Have completed a full database backup

You may also wish to apply these changes in a test environment before applying them to production.

When to apply this fix

If you notice that your content is not displaying correctly, you should apply this fix. For example, if you have the string José that is being displayed as José, that is an example of when to apply this fix.

Repairing a column with incorrectly encoded content

You'll need to select the column converting to the previousEncoding (such as latin1) and cast it to binary; then to utf8.

Setting SQL_SAFE_UPDATES to 0 before issuing the query allows you to update each row in the table. This is potentially unsafe, and should be tested thoroughly before being applied to a production system.

UPDATE tableName SET columnName = CONVERT(CAST(CONVERT(columnName USING previousEncoding) AS BINARY) USING utf8);

Depending on the character and how it's encoded, this query may not be enough to resolve the encoding issues you're seeing. You may wish to try one of the alternative methods outlined in the "Further Reading" section below.

Further Reading:

Last modified on Feb 19, 2016

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