MariaDB Plans - Statistics and Monitoring

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Notes from the Statistics and Monitoring group:

  • Strategic direction: Enterprise monitoring
    • graphing and data aggregation tools, server monitoring, etc.
    • customer has reported that Merlin is inadequate, should we enter into this market?
  • QA request: better EXPLAIN:
    • required in order to debug performance issues in queries without knowing the query or the data;
    • the customer will only provide EXPLAIN and SHOW output, we need to debug based on that;
    • required to ensure repeatable query execution for InnoDB;
    • may allow various statistics to be reported by the server regardless of engine;
  • U/C at Oracle: OPTIMIZER tracing spetrunia: report actual estimates, and all decisions of the optimizer, including why an index was *not* picked, etc.
  • Developed by Serg for MariaDB 5.3: Phone Home todo: make a web page on showing the results from the data being collected; pstoev: do we need to allow people to run their own reporting servers;
  • Present in MySQL 5.5: Performance Schema
    • what do we want to do with it, embrace it, extend it?
    • or it is better to have more SHOW commands and INFORMATION_SCHEMA tables?
    • are going to use Facebook's user stats/index stats patch or create a PERFORMANCE_SCHEMA-based solution?
  • FB request: log all SQL errors
    • serg: possible via AUDIT plugin, must back-port audit infrastructure from MySQL 5.5
  • FB request: more options for controlling the slow query log
    • sample one out of every N queries or transactions ; with N ~ 99
    • filter queries based on rows examined, I/O performed, total lock wait time;
  • idea: collect statistics per query text, or normalized query text and report;
  • FB request: EXPLAIN the *actual* plan on a *running* statement; no progress indicators and numbers are needed;
  • request by community: progress bar for queries such as LOAD DATA and SELECT;
    • what numbers are to be reported? time to elapsed, time to completion, number of rows processed?
    • how to estimate the total runing time of the query;
  • FB request: limit total temptable size on the server; Already available per-query, but per-server needed;
  • FB patch: Admission Control
    • limit number of concurrently running queries per user;
    • if all user queries are blocked, allow a few more queries to join;
  • Kurt: Integration with log watching tools
    • alter log formats to make them compatible with tools;
    • include logwatch mysql-specific config file in packages/distributions;
  • FB request: Better monitoring for replication:
    • seconds_behind_master computation is incorrect, sometimes is zero
    • a counter for the total number of bytes read by I/O thread that does not rotate on log rotation;
    • "seconds behind real master" to report the actual time the slave I/O thread is behind;
  • community request: prevent full scans from running at all above a certain table size;
    • is existing max-join-size variable sufficient or more granula control is needed?
  • FB patch: report the time spent in individual phases of query processing


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