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# include/check_qep.inc
#
# SUMMARY
#
# Designed to be used together with include/expect_qep.inc
#
# $query should be assigned a select statement using
# straight_join to force the tables to be joined in most
# optimal order.
#
# expect_qep.inc will then store the estimated 'Last_query_cost'
# and total # 'Handler_read%' for this straight_joined query.
#
# We should then assign a non-straight_join'ed version of
# the same query to $query and execute it using
# 'include/check_qep.inc'. Its estimated cost and
# #handler_reads will then be verified against the
# previous straight_joined query.
#
# USAGE
#
# let $query= <select straight_join optimal statement>;
# --source include/expect_qep.inc
# let $query= <select statement>;
# --source include/check_qep.inc
#
# EXAMPLE
# t/greedy_optimizer.test
#
flush status;
eval EXPLAIN $query;
--disable_ps2_protocol
eval $query;
--enable_ps2_protocol
let $cost=
query_get_value(SHOW STATUS LIKE 'Last_query_cost', Value, 1);
--disable_warnings
let $reads=
`select sum(variable_value)
from information_schema.session_status
where VARIABLE_NAME like 'Handler_read%'`;
--enable_warnings
#echo Cost: $cost, Handler_reads: $reads;
if ($cost != $best_cost)
{ echo ### FAILED: Query_cost: $cost, expected: $best_cost ###;
}
# Difference in handler reads are ok as tables in MariaDB are sorted according
# to order in the query and the tables in greedy_optimizer.inc has reference to
# rows that does not exists, so different table orders will do different
# number of reads
if ($reads != $best_reads)
{ echo ### NOTE: Handler_reads: $reads, expected: $best_reads ###;
}
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