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SELECT * FROM mysql.server_cost;
cost_name cost_value last_update comment
disk_temptable_create_cost NULL # NULL
disk_temptable_row_cost NULL # NULL
key_compare_cost NULL # NULL
memory_temptable_create_cost NULL # NULL
memory_temptable_row_cost NULL # NULL
row_evaluate_cost NULL # NULL
SHOW INDEX FROM mysql.server_cost;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
server_cost 0 PRIMARY 1 cost_name A # NULL NULL BTREE
SELECT * FROM mysql.engine_cost;
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost NULL # NULL
default 0 memory_block_read_cost NULL # NULL
SHOW INDEX FROM mysql.engine_cost;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
engine_cost 0 PRIMARY 1 cost_name A # NULL NULL BTREE
engine_cost 0 PRIMARY 2 engine_name A # NULL NULL BTREE
engine_cost 0 PRIMARY 3 device_type A # NULL NULL BTREE
UPDATE mysql.server_cost
SET cost_value=0.1
WHERE cost_name="row_evaluate_cost";
SELECT *
FROM mysql.server_cost
WHERE cost_name="row_evaluate_cost";
cost_name cost_value last_update comment
row_evaluate_cost 0.1 # NULL
UPDATE mysql.server_cost
SET cost_value=DEFAULT
WHERE cost_name="row_evaluate_cost";
SELECT *
FROM mysql.server_cost
WHERE cost_name="row_evaluate_cost";
cost_name cost_value last_update comment
row_evaluate_cost NULL # NULL
INSERT INTO mysql.server_cost
VALUES ("lunch_cost", DEFAULT, CURRENT_TIMESTAMP, "Lunch is important");
SELECT * FROM mysql.server_cost;
cost_name cost_value last_update comment
disk_temptable_create_cost NULL # NULL
disk_temptable_row_cost NULL # NULL
key_compare_cost NULL # NULL
lunch_cost NULL # Lunch is important
memory_temptable_create_cost NULL # NULL
memory_temptable_row_cost NULL # NULL
row_evaluate_cost NULL # NULL
DELETE FROM mysql.server_cost
WHERE cost_name="lunch_cost";
INSERT INTO mysql.server_cost
VALUES ("row_evaluate_cost", DEFAULT, CURRENT_TIMESTAMP, "Faster CPU");
ERROR 23000: Duplicate entry 'row_evaluate_cost' for key 'PRIMARY'
INSERT INTO mysql.server_cost
VALUES ("ROW_EVALUATE_COST", DEFAULT, CURRENT_TIMESTAMP, "Faster CPU");
ERROR 23000: Duplicate entry 'ROW_EVALUATE_COST' for key 'PRIMARY'
SELECT * FROM mysql.server_cost;
cost_name cost_value last_update comment
disk_temptable_create_cost NULL # NULL
disk_temptable_row_cost NULL # NULL
key_compare_cost NULL # NULL
memory_temptable_create_cost NULL # NULL
memory_temptable_row_cost NULL # NULL
row_evaluate_cost NULL # NULL
UPDATE mysql.engine_cost
SET cost_value=0.1
WHERE cost_name="io_block_read_cost";
SELECT *
FROM mysql.engine_cost
WHERE cost_name="io_block_read_cost";
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost 0.1 # NULL
UPDATE mysql.engine_cost
SET cost_value=DEFAULT
WHERE cost_name="io_block_read_cost";
SELECT *
FROM mysql.engine_cost
WHERE cost_name="io_block_read_cost";
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost NULL # NULL
INSERT INTO mysql.engine_cost
VALUES ("InnoDB", 2, "lunch_cost1", DEFAULT, CURRENT_TIMESTAMP, "Lunch 1"),
("InnoDB", 2, "lunch_cost2", DEFAULT, CURRENT_TIMESTAMP, "Lunch 2");
SELECT * FROM mysql.engine_cost;
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost NULL # NULL
InnoDB 2 lunch_cost1 NULL # Lunch 1
InnoDB 2 lunch_cost2 NULL # Lunch 2
default 0 memory_block_read_cost NULL # NULL
DELETE FROM mysql.engine_cost
WHERE cost_name LIKE "lunch_cost%";
INSERT INTO mysql.engine_cost
VALUES ("default", 0, "lunch_cost", DEFAULT, CURRENT_TIMESTAMP, "Lunch");
INSERT INTO mysql.engine_cost
VALUES ("default", 0, "lunch_cost", DEFAULT, CURRENT_TIMESTAMP, "Lunch");
ERROR 23000: Duplicate entry 'lunch_cost-default-0' for key 'PRIMARY'
SELECT * FROM mysql.engine_cost;
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost NULL # NULL
default 0 lunch_cost NULL # Lunch
default 0 memory_block_read_cost NULL # NULL
DELETE FROM mysql.engine_cost
WHERE cost_name="lunch_cost";
INSERT INTO mysql.engine_cost
VALUES ("default", 0, "IO_BLOCK_READ_COST", DEFAULT, CURRENT_TIMESTAMP,
"Lunch");
ERROR 23000: Duplicate entry 'IO_BLOCK_READ_COST-default-0' for key 'PRIMARY'
SELECT * FROM mysql.engine_cost;
engine_name device_type cost_name cost_value last_update comment
default 0 io_block_read_cost NULL # NULL
default 0 memory_block_read_cost NULL # NULL
CREATE TABLE server_cost_tmp (
cost_name VARCHAR(64) NOT NULL,
last_update TIMESTAMP
);
CREATE TABLE engine_cost_tmp (
cost_name VARCHAR(64) NOT NULL,
last_update TIMESTAMP
);
INSERT INTO server_cost_tmp
SELECT cost_name, last_update FROM mysql.server_cost;
INSERT INTO engine_cost_tmp
SELECT cost_name, last_update FROM mysql.engine_cost;
UPDATE mysql.server_cost
SET cost_value=0.1
WHERE cost_name="row_evaluate_cost";
SELECT mysql.server_cost.cost_name
FROM mysql.server_cost JOIN server_cost_tmp
ON mysql.server_cost.cost_name = server_cost_tmp.cost_name
WHERE mysql.server_cost.last_update > server_cost_tmp.last_update;
cost_name
row_evaluate_cost
UPDATE mysql.server_cost
SET cost_value=DEFAULT
WHERE cost_name="row_evaluate_cost";
UPDATE mysql.engine_cost
SET cost_value=2.0
WHERE cost_name="io_block_read_cost";
SELECT mysql.engine_cost.cost_name
FROM mysql.engine_cost JOIN engine_cost_tmp
ON mysql.engine_cost.cost_name = engine_cost_tmp.cost_name
WHERE mysql.engine_cost.last_update > engine_cost_tmp.last_update;
cost_name
io_block_read_cost
UPDATE mysql.engine_cost
SET cost_value=DEFAULT
WHERE cost_name="io_block_read_cost";
DROP TABLE server_cost_tmp, engine_cost_tmp;