CODEWITHSUNDEEP
mysqlindexingphpmyadmin
user2342558
user2342558

Reputation: 6731

Mysql phpmyadmin show empty cardinality

Why does phpMyAdmin show an empty cardinality? enter image description here

If I edit the index (without change anything) and save, the cardinality will appear, but after a TRUNCATE and some INSERTs, the cardinality become empty again.

Running

ALTER TABLE tableName ENABLE KEYS

doesn't help.

How to make the cardinality always present?

Edit:

The phpMyAdmin version is 4.6.4

The MySql version is libmysql - mysqlnd 5.0.12-dev - 20150407

The Engine is MyISAM

Upvotes: 1

Views: 2765

Answers (2)

Rick James
Rick James

Reputation: 142453

Aha -- I found NULLs with SHOW INDEXES on a MyISAM table. Is yours ENGINE=MyISAM? Recommend changing to InnoDB.

Upvotes: 0

symcbean
symcbean

Reputation: 48387

You need to analyze the table.

ANALYZE LOCAL TABLE tablename

The stats for the primary key are updated when the data is updated, but the other indexes need this operation to set a value. Note that if the distribution of the data is not changing then you don't need to refresh the indexes.

Note that there is a performance impact (and locking impact with MyISAM) on large tables when you run this.

Upvotes: 2

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