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8916aeed28
(Patch provided by Monty, Testcase by Rex Johnston) get_tmp_table_costs() computes the cost of using a temporary (work table) for certain cases, including semi-join subquery materialization. The computed cost value was very low, it used this formula: key_lookup_cost * (disk_read_ratio= 0.02) Use the correct formula: key_lookup_cost // Index lookup is always done + disk_read_cost * disk_read_ratio disk_read_cost is incurred when the lookup has to go to disk. We assume this doesn't occur for every lookup. It happens only with disk_read_ratio=0.02 frequency. The fix is controlled by @@new_mode='FIX_DISK_TMPTABLE_COSTS' flag. It is OFF by default in this patch.
53 lines
1.3 KiB
Text
53 lines
1.3 KiB
Text
--source include/load_sysvars.inc
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--source include/have_debug.inc
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SET @global_start_value = @@global.new_mode;
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SELECT @global_start_value;
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SET @session_start_value = @@session.new_mode;
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SELECT @session_start_value;
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SET @@global.new_mode = "FIX_DISK_TMPTABLE_COSTS";
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SELECT @@global.new_mode;
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SELECT @@session.new_mode;
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SET @@global.new_mode = DEFAULT;
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SELECT @@global.new_mode;
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SELECT @@session.new_mode;
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SET @@session.new_mode = "FIX_DISK_TMPTABLE_COSTS,TEST_WARNING1";
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SET @@session.new_mode = "FIX_DISK_TMPTABLE_COSTS,TEST_WARNING1,TEST_WARNING2";
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--Error ER_WRONG_VALUE_FOR_VAR
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SET @@session.new_mode = "FIX_DISK_TMPTABLE_COSTS,TEST_WARNING1,TEST_WARNING2,TEST_WARNING3";
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SET @@session.new_mode = "ALL";
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select @@session.new_mode;
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--Error ER_WRONG_VALUE_FOR_VAR
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SET @@global.new_mode = NULL;
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SET @@global.new_mode = '';
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SELECT @@global.new_mode;
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SET @@global.new_mode = ' ';
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SELECT @@global.new_mode;
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--Error ER_WRONG_VALUE_FOR_VAR
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SET @@session.new_mode = NULL;
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SET @@session.new_mode = '';
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SELECT @@session.new_mode;
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SET @@session.new_mode = ' ';
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SELECT @@session.new_mode;
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--Error ER_WRONG_VALUE_FOR_VAR
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SET @@global.new_mode = OFF;
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--Error ER_WRONG_VALUE_FOR_VAR
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SET @@session.new_mode = OFF;
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SET @@global.new_mode = @global_start_value;
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SELECT @@global.new_mode;
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SET @@session.new_mode = @session_start_value;
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SELECT @@session.new_mode;
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