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  1. MariaDB Server
  2. MDEV-3889

table elimination an a chain of left joins

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Minor
        • Resolution: Won't Fix
        • Affects Version/s: 5.5.28, 5.3.10
        • Fix Version/s: None
        • Component/s: None
        • Labels:
          None

          Description

          In the following test case:

          drop table if exists t1, t2, t3;
create table t1 (id int, key (id));
insert t1 values (1),(2);
create table t2 (t1_id int primary key, id int, key (id));
insert t2 values (1,1),(2,2);
create table t3 (t2_id int primary key);
insert t3 values (1),(2);
set sql_quote_show_create=0;
explain extended select t1.id from t1 left join
    t2 on t1.id = t2.t1_id left join t3 on t2.id = t3.t2_id;

          the optimizer is supposed to eliminate both t2 and t3 from the query plan, but it only removes t3.

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                psergey Sergei Petrunia added a comment -

                Don't see a demand for resolving this (Does anybody use table elimination to the extent that they are affected?) Feel free to re-open if it affects you.

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                psergey Sergei Petrunia added a comment - Don't see a demand for resolving this (Does anybody use table elimination to the extent that they are affected?) Feel free to re-open if it affects you.

                  People

                  • Assignee:
                    psergey Sergei Petrunia
                    Reporter:
                    serg Sergei Golubchik
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                    • Created:
                      Updated:
                      Resolved: