Speed up main.sum_distinct-big

Eliminate one InnoDB table with 128*16384 rows, and use
the sequence engine instead. Also, run everything in a single
transaction, to prevent purge from running concurrently
unnecessarily. (Starting with MariaDB Server 10.3, purge would
reset the DB_TRX_ID after INSERT.)

mysql-test/r/sum_distinct-big.result

-DROP TABLE IF EXISTS t1, t2;
 set @save_tmp_table_size=@@tmp_table_size;
 set @save_max_heap_table_size=@@max_heap_table_size;
-set @save_storage_engine=@@storage_engine;
 set storage_engine=MYISAM;
 CREATE TABLE t1 (id INTEGER);
 CREATE TABLE t2 (id INTEGER);
@@ -126,35 +124,13 @@ DROP TABLE t1;
 DROP TABLE t2;
 SET @@tmp_table_size=@save_tmp_table_size;
 SET @@max_heap_table_size=@save_max_heap_table_size;
-# 
-# Bug mdev-4311: COUNT(DISTINCT...) requiring a file for Unique 
-# (bug #68749)
-# 
-set @save_storage_engine=@@storage_engine;
-set storage_engine=INNODB;
-CREATE TABLE t1 (id INTEGER) ENGINE=InnoDB;
+#
+# MDEV-4311: COUNT(DISTINCT...) requiring a file for UNIQUE (bug #68749)
+#
 CREATE TABLE t2 (id INTEGER) ENGINE=InnoDB;
-INSERT INTO t1 (id) VALUES (1), (1), (1),(1);
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 SELECT id+1 FROM t1;
-INSERT INTO t1 SELECT id+2 FROM t1;
-INSERT INTO t1 SELECT id+4 FROM t1;
-INSERT INTO t1 SELECT id+8 FROM t1;
-INSERT INTO t1 SELECT id+16 FROM t1;
-INSERT INTO t1 SELECT id+32 FROM t1;
-INSERT INTO t1 SELECT id+64 FROM t1;
-INSERT INTO t1 SELECT id+128 FROM t1;
-INSERT INTO t1 SELECT id+256 FROM t1;
-INSERT INTO t1 SELECT id+512 FROM t1;
-INSERT INTO t1 SELECT id+1024 FROM t1;
-INSERT INTO t1 SELECT id+2048 FROM t1;
-INSERT INTO t1 SELECT id+4096 FROM t1;
-INSERT INTO t1 SELECT id+8192 FROM t1;
-INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
+BEGIN;
+INSERT INTO t2 SELECT b.seq FROM seq_1_to_128 a, seq_1_to_16384 b
+ORDER BY b.seq*rand();
 INSERT INTO t2 VALUE(NULL);
 # With default tmp_table_size / max_heap_table_size
 SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
@@ -176,5 +152,5 @@ SET @@max_heap_table_size=@save_max_heap_table_size;
 SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
 sm
 16384
-DROP TABLE t1,t2;
-set storage_engine=@save_storage_engine;
+COMMIT;
+DROP TABLE t2;

mysql-test/t/sum_distinct-big.test

@@ -4,15 +4,11 @@
 
 --source include/big_test.inc
 --source include/have_innodb.inc
---disable_warnings
-DROP TABLE IF EXISTS t1, t2;
---enable_warnings
+--source include/have_sequence.inc
 
 set @save_tmp_table_size=@@tmp_table_size;
 set @save_max_heap_table_size=@@max_heap_table_size;
 
-set @save_storage_engine=@@storage_engine;
-
 #
 # Test the case when distinct values doesn't fit in memory and 
 # filesort is used (see uniques.cc:merge_walk)
@@ -94,39 +90,14 @@ DROP TABLE t2;
 SET @@tmp_table_size=@save_tmp_table_size;
 SET @@max_heap_table_size=@save_max_heap_table_size;
 
---echo # 
---echo # Bug mdev-4311: COUNT(DISTINCT...) requiring a file for Unique 
---echo # (bug #68749)
---echo # 
-
-set @save_storage_engine=@@storage_engine;
-set storage_engine=INNODB;
-
-CREATE TABLE t1 (id INTEGER) ENGINE=InnoDB;
+--echo #
+--echo # MDEV-4311: COUNT(DISTINCT...) requiring a file for UNIQUE (bug #68749)
+--echo #
 CREATE TABLE t2 (id INTEGER) ENGINE=InnoDB;
 
-INSERT INTO t1 (id) VALUES (1), (1), (1),(1);
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 (id) SELECT id FROM t1;
-INSERT INTO t1 SELECT id+1 FROM t1;
-INSERT INTO t1 SELECT id+2 FROM t1;
-INSERT INTO t1 SELECT id+4 FROM t1;
-INSERT INTO t1 SELECT id+8 FROM t1;
-INSERT INTO t1 SELECT id+16 FROM t1;
-INSERT INTO t1 SELECT id+32 FROM t1;
-INSERT INTO t1 SELECT id+64 FROM t1;
-INSERT INTO t1 SELECT id+128 FROM t1;
-INSERT INTO t1 SELECT id+256 FROM t1;
-INSERT INTO t1 SELECT id+512 FROM t1;
-INSERT INTO t1 SELECT id+1024 FROM t1;
-INSERT INTO t1 SELECT id+2048 FROM t1;
-INSERT INTO t1 SELECT id+4096 FROM t1;
-INSERT INTO t1 SELECT id+8192 FROM t1;
-
-INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
+BEGIN;
+INSERT INTO t2 SELECT b.seq FROM seq_1_to_128 a, seq_1_to_16384 b
+ORDER BY b.seq*rand();
 INSERT INTO t2 VALUE(NULL);
 
 --echo # With default tmp_table_size / max_heap_table_size
@@ -147,7 +118,6 @@ SET @@max_heap_table_size=@save_max_heap_table_size;
 
 --echo # Back to default tmp_table_size / max_heap_table_size
 SELECT SQL_NO_CACHE count(DISTINCT id) sm FROM t2;
+COMMIT;
 
-DROP TABLE t1,t2;
-
-set storage_engine=@save_storage_engine;
+DROP TABLE t2;