1 files changed, 66 insertions, 0 deletions
diff --git a/mysql-test/main/range_notembedded.test b/mysql-test/main/range_notembedded.test
index 4dc49429ff1..d50bec23148 100644
--- a/mysql-test/main/range_notembedded.test
+++ b/mysql-test/main/range_notembedded.test
@@ -31,3 +31,69 @@ from information_schema.optimizer_trace;
 set optimizer_trace=@tmp_21958;
 
 drop table t2;
+--echo #
+--echo # MDEV-9750: Quick memory exhaustion with 'extended_keys=on'...
+--echo #
+
+create table t1 (
+   kp1 int,
+   kp2 int,
+   kp3 int,
+   kp4 int,
+   key key1(kp1, kp2, kp3,kp4)
+);
+
+insert into t1 values (1,1,1,1),(2,2,2,2),(3,3,3,3);
+analyze table t1;
+
+show variables like 'optimizer_max_sel_arg_weight';
+
+# 20 * 20 * 20 *20 = 400*400 = 160,000 ranges
+set @tmp_9750=@@optimizer_trace;
+set optimizer_trace=1;
+explain select * from t1 where 
+  kp1 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
+  kp2 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
+  kp3 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) and
+  kp4 in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20)
+;
+
+set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
+            from information_schema.optimizer_trace);
+--echo # This will show 3-component ranges. 
+--echo # The ranges were produced, but the optimizer has cut away kp4
+--echo #  to keep the number of ranges at manageable level:
+select left(@json, 500);
+
+--echo ## Repeat the above with low max_weight:
+set @tmp9750_weight=@@optimizer_max_sel_arg_weight;
+set optimizer_max_sel_arg_weight=20;
+explain select * from t1 where 
+  kp1 in (1,2,3,4,5,6,7,8,9,10) and
+  kp2 in (1,2,3,4,5,6,7,8,9,10) and
+  kp3 in (1,2,3,4,5,6,7,8,9,10) and
+  kp4 in (1,2,3,4,5,6,7,8,9,10)
+;
+set @trace= (select trace from information_schema.optimizer_trace);
+set @json= json_detailed(json_extract(@trace, '$**.range_scan_alternatives'));
+select left(@json, 500);
+
+set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
+select left(@json, 2500);
+
+--echo ## Repeat the above with a bit higher max_weight:
+set @tmp9750_weight=@@optimizer_max_sel_arg_weight;
+set optimizer_max_sel_arg_weight=120;
+explain select * from t1 where 
+  kp1 in (1,2,3,4,5,6,7,8,9,10) and
+  kp2 in (1,2,3,4,5,6,7,8,9,10) and
+  kp3 in (1,2,3,4,5,6,7,8,9,10) and
+  kp4 in (1,2,3,4,5,6,7,8,9,10)
+;
+set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
+            from information_schema.optimizer_trace);
+select left(@json, 1500);
+
+set optimizer_max_sel_arg_weight= @tmp9750_weight;
+set optimizer_trace=@tmp_9750;
+drop table t1;