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#
# Bug#23508576 FILL_INDEXES_FROM_DD() DOES NOT INITIALIZE
# ST_KEY::M_IN_MEMORY_ESTIMATE
#
UPDATE mysql.engine_cost
SET cost_value=0.5
WHERE cost_name="memory_block_read_cost";
UPDATE mysql.engine_cost
SET cost_value=2
WHERE cost_name="io_block_read_cost";
FLUSH OPTIMIZER_COSTS;
SELECT engine_name, device_type, cost_name, cost_value
FROM mysql.engine_cost
WHERE cost_name="memory_block_read_cost"
OR cost_name="io_block_read_cost";
engine_name device_type cost_name cost_value
default 0 io_block_read_cost 2
default 0 memory_block_read_cost 0.5
CREATE TABLE t1 (
i1 INTEGER,
c1 CHAR(200),
INDEX idx (i1)
) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1, "Ullensvang"), (2, "Odda"), (3, "Jondal");
# Pass criteria for the query plan:
# 1. Should be executed as an index-only range scan
# 2. Cost estimate: "read_cost" - "eval_cost" should be approximately
# the cost of reading one page from memory, ie. about 0.5.
EXPLAIN FORMAT=JSON
SELECT i1 FROM t1 WHERE i1 > 1;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "0.92"
},
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"idx"
],
"key": "idx",
"used_key_parts": [
"i1"
],
"key_length": "5",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "0.72",
"eval_cost": "0.20",
"prefix_cost": "0.92",
"data_read_per_join": "1K"
},
"used_columns": [
"i1"
],
"attached_condition": "(`test`.`t1`.`i1` > 1)"
}
}
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i1` AS `i1` from `test`.`t1` where (`test`.`t1`.`i1` > 1)
DROP TABLE t1;
UPDATE mysql.engine_cost
SET cost_value=DEFAULT;
FLUSH OPTIMIZER_COSTS;
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