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  1. MariaDB Server
  2. MDEV-36125

New-style hint: [NO_]INDEX_MERGE

Details

    • Server 12.1 dev sprint

    Description

      Implement the new-style hints:

      INDEX_MERGE
      		 
      NO_INDEX_MERGE

      in a way compatible to MySQL.
      MySQL's Work Log: https://dev.mysql.com/worklog/task/?id=9167

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          split from

          Epic - Created by Jira Software - do not edit or delete. Issue type for a big user story that needs to be broken down. MDEV-33281 Implement optimizer hints like in MySQL 8

          • Critical - Crashes, loss of data, severe memory leak.
          • In Progress

          Activity

            Gosselin Dave Gosselin added a comment - - edited

            Both our code and the referenced MySQL work log mention not only index merge but also others (like index_merge_union). Judging from our code, it appears that codepaths where some index_merge_* optimizer switch is used are gated by the index merge option itself (as though it is a top-level switch) so it appears sufficient for the new hint to affect only index merge, and the others will either be enabled or disabled accordingly. Testing will bear it out and I'll update accordingly.

            Gosselin Dave Gosselin added a comment - - edited Both our code and the referenced MySQL work log mention not only index merge but also others (like index_merge_union). Judging from our code, it appears that codepaths where some index_merge_* optimizer switch is used are gated by the index merge option itself (as though it is a top-level switch) so it appears sufficient for the new hint to affect only index merge, and the others will either be enabled or disabled accordingly. Testing will bear it out and I'll update accordingly.

            People

              Gosselin Dave Gosselin
              psergei Sergei Petrunia
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