Current File : //usr/share/mysql-test/suite/opt_trace/t/eq_range_statistics.test
# Tests for eq_range_index_dive_limit variable:
# test that the number of ranges are counted correctly and
# index statistics kicks in when more than
# eq_range_index_dive_limit equality ranges are in the
# predicate
--source include/have_optimizer_trace.inc
--source include/have_debug.inc
SET optimizer_trace_max_mem_size=1048576; # 1MB
SET optimizer_trace="enabled=on,one_line=off";
SET end_markers_in_json="on";
SET eq_range_index_dive_limit=default;
SELECT @@eq_range_index_dive_limit;
CREATE TABLE t1 (
a INT,
b INT,
KEY (a,b)
);
INSERT INTO t1 VALUES (1,1), (2,2), (3,3);
INSERT INTO t1 VALUES (4,1), (4,2), (4,3);
INSERT INTO t1 VALUES (5,1), (5,2), (5,3);
SHOW INDEX FROM t1;
ANALYZE TABLE t1;
SHOW INDEX FROM t1;
--echo #####
--echo # Apply knowledge about the statistics (each index value for
--echo # the first key part has an estimate of 2 rows) to ensure that
--echo # index statistics kicks in correctly.
--echo #####
--echo # Index dives are done, giving correct estimate of 3 records
EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3);
SET eq_range_index_dive_limit=3;
SELECT @@eq_range_index_dive_limit;
# Crash server if records_in_range() is called
SET SESSION DEBUG="+d,crash_records_in_range";
--echo # Index statistics kicks in, giving incorrect estimate of 3x2=6 records
EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3);
SELECT * FROM t1 WHERE a IN (1,2,3);
SET SESSION DEBUG="-d,crash_records_in_range";
--echo #####
--echo # Below: A number of tests to verify that the number of equality ranges
--echo # are counted correctly
--echo #####
# The limit is 3
--echo
--echo # 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
# This query will use index statistics (as shown in trace) but
# we cannot make it crash if records_in_range() is called
# because the "a>10" range will correctly call records_in_range()
--echo
--echo # 3 equality ranges: should use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1,2);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
# Crash server if records_in_range() is called
--echo
--echo # 3 equality ranges: should use index statistics
SET SESSION DEBUG="+d,crash_records_in_range";
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b=4);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
SET SESSION DEBUG="-d,crash_records_in_range";
--echo
--echo # 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b>4);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
--echo
--echo # 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b IS NULL);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
--echo
--echo # 0 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a>5 AND (b=2 OR b=3 OR b=4);
SELECT * FROM information_schema.OPTIMIZER_TRACE;
# Turn index statistics off
SET eq_range_index_dive_limit=0;
--echo
--echo # 1 equality range: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5;
SELECT * FROM information_schema.OPTIMIZER_TRACE;
DROP TABLE t1;
SET eq_range_index_dive_limit=default;
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