Question

Urgent: Your [placeholder] database’s functionality is at risk

I’ve been getting these emails daily from DigitalOcean:

Our systems have indicated that your MySQL cluster, [placeholder], has tables without primary keys. We have identified that MySQL tables without primary keys can lead to service replication issues that jeopardize performance and availability. If primary keys are not present for database tables exceeding 5,000 rows, data-loss can occur.

We urge you to take the following actions to ensure that your database [placeholder] continues to operate correctly:

  1. Review the following product documentation which details the issue and provides clear mitigation strategies for all impacted users.
  2. Implement primary keys for all database tables as described in the documentation.

See the full details at the following link: https://www.digitalocean.com/docs/databases/mysql/how-to/create-primary-keys/

We will continue to notify you of this issue until all MySQL tables have primary keys.

I used the following SQL query to find tables without indexes:

SELECT t.*
FROM INFORMATION_SCHEMA.TABLES t
LEFT JOIN INFORMATION_SCHEMA.COLUMNS c ON c.TABLE_NAME = t.TABLE_NAME
	AND c.COLUMN_KEY = 'PRI'
WHERE c.TABLE_SCHEMA IS NULL
	AND TABLE_TYPE NOT IN ('SYSTEM VIEW', 'VIEW', 'CSV');

I found a few tables that didn’t have primary keys, corrected the issue, and now the only remaining tables are:

  • performance_schema (lots of tables)
  • mysql (general_log and slow_log, which use the CSV engine)

I created a brand new database and did the same query on the new DB and the results on the new DB matched the results on the old DB. Like both queries returned 51 results.


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Accepted Answer

DigitalOcean support gave me this alternative query to run to find the problem tables:

SELECT
    tab.table_schema AS database_name,
    tab.table_name AS table_name,
    tab.table_rows AS table_rows
FROM information_schema.tables tab
LEFT JOIN information_schema.table_constraints tco
    ON (tab.table_schema = tco.table_schema
        AND tab.table_name = tco.table_name
        AND tco.constraint_type = 'PRIMARY KEY')
WHERE
    tab.table_schema NOT IN ('mysql', 'information_schema', 'performance_schema', 'sys')
    AND tco.constraint_type IS NULL
    AND tab.table_type = 'BASE TABLE';

It sound one table mine didn’t. The difference between mine and this one is that mine was looking at INFORMATION_SCHEMA.COLUMNS.COLUMN_KEY whereas this one is looking at INFORMATION_SCHEMA.TABLE_CONSTRAINTS.CONSTRAINT_NAME

Hi @jimwigginton,

From you’ve written, I think you’ve corrected the missing primary keys, is that correct? As such you shouldn’t be getting such messages already or are you still getting them?