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  1. MariaDB Server
  2. MDEV-7901

re-implement analyze table for low impact

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    • Sprint:
      10.1.6-1, 10.1.6-2, 10.1.7-1, 10.2.0-5, 10.2.0-6, 5.5.51 & 10.2.2

      Description

      MDEV-7829 and MDEV-7363 where attempts to work around the implementation of analyze table because holding a read lock only on the entire table while gathers statistics. This can be up to an hour or so on larger tables as witnessed in production databases. This level of total read only on a table isn't acceptable.

      MDEV-7196 suggested by Jan Lindström indicated that perhaps a full scan is more appropriate to give better statistics. Obviously this isn't going to help the locking scenario at all.

      So perhaps, instead of locking the entire table, the analyze table takes a full table scan in incremental blocks. These block sizes should try to scale to something that keeps the lock time less that a goal time, a new variable max_analyze_table_lock_time (locks can be dropped in analyze table gets there too soon). Analyze table being a long running operation should drop to read committed (or uncommitted?) mode to keep the undo logs from growing because of the intensive read operations.

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              • Assignee:
                sanja Oleksandr Byelkin
                Reporter:
                danblack Daniel Black
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                • Created:
                  Updated:
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