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  1. MariaDB Server
  2. MDEV-14569

Query runs slower using a UNIQUE KEY vs. a KEY

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      Description

      I have an old Request Tracker 3.6 setup using MariaDB 10.2.10 (recently rebuilt, was on MySQL 5.5 before and did not have this issue). I noticed that a query that includes searching by the requester Name is much slower than searching by the EmailAddress. When I look at the SQL query generated, the only difference is searching by the Users.Name column vs. the Users.EmailAddress column. The Name column is a UNIQUE KEY while the EmailAddress column is just a KEY (each of the keys has just the one column). That doesn't seem like it should cause a big difference.

      I'm attaching the Users table schema as well as "explain extended" of the two queries.

        Attachments

        1. explain-email.txt
          3 kB
        2. explain-name.txt
          3 kB
        3. tables.sql
          2 kB
        4. Users.sql
          1 kB

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              Assignee:
              alice Alice Sherepa
              Reporter:
              cmadams Chris Adams
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