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  1. MariaDB Server
  2. MDEV-6941

SET STATEMENT affects the value of the GLOBAL variable for the duration of the statement

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      Description

      Output of the test case below

      # Initial values
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;
      @@global.lock_wait_timeout	@@lock_wait_timeout
      31536000	31536000
      # 
      set statement lock_wait_timeout=11 for show global variables like 'lock_wait_timeout';
      Variable_name	Value
      lock_wait_timeout	31536000
      SET STATEMENT lock_wait_timeout=12 FOR SELECT SLEEP(2.5);
      connect con1,localhost,root;
      # 
      # It's a new connection, so it picked up the current value 
      # of the global variable for the session variable
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;
      @@global.lock_wait_timeout	@@lock_wait_timeout
      12	12
      # 
      # Now SET STATEMENT in the other connection ended, so the global value
      # is back to normal (but the session one is not)
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;
      @@global.lock_wait_timeout	@@lock_wait_timeout
      31536000	12

      Test case

      --enable_connect_log
       
      --echo # Initial values
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;
       
      --echo # 
      set statement lock_wait_timeout=11 for show global variables like 'lock_wait_timeout';
      --send SET STATEMENT lock_wait_timeout=12 FOR SELECT SLEEP(2.5)
       
      --sleep 1
      --connect(con1,localhost,root)
      --echo # 
      --echo # It's a new connection, so it picked up the current value 
      --echo # of the global variable for the session variable
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;
      --sleep 2
      --echo # 
      --echo # Now SET STATEMENT in the other connection ended, so the global value
      --echo # is back to normal (but the session one is not)
      SELECT @@global.lock_wait_timeout, @@lock_wait_timeout;

      commit 3a3f88e789a41b309cfe902f4823c9c7ebbce6ca
      Author: Oleksandr Byelkin <sanja@mariadb.com>
      Date:   Fri Oct 24 10:13:08 2014 +0200
       
          MDEV-5231: Per query variables from Percona Server (rewritten)

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              Assignee:
              sanja Oleksandr Byelkin
              Reporter:
              elenst Elena Stepanova
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