Bug#38005 Partitions: error with insert select.

MyISAM blocks index usage for bulk insert into zero-records tables.
See ha_myisam::start_bulk_insert() lines from
...
    if (file->state->records == 0 ...
...

That causes problems for partition engine when some partitions have records some not
as the engine uses same access method for all partitions.

Now partition engine doesn't call index_first/index_last
for empty tables.

per-file comments:
  mysql-test/r/partition.result
        Bug#38005 Partitions: error with insert select.
        test result

  mysql-test/t/partition.test
        Bug#38005 Partitions: error with insert select.
        test case

  sql/ha_partition.cc
        Bug#38005 Partitions: error with insert select.
        ha_engine::index_first and
        ha_engine::index_last not called for empty tables.

1 files changed, 49 insertions, 0 deletions

diff --git a/mysql-test/t/partition.test b/mysql-test/t/partition.test
index 5270eced05f..970eb3e6f35 100644
--- a/mysql-test/t/partition.test
+++ b/mysql-test/t/partition.test
@@ -1791,4 +1791,53 @@ select count(*) from t1, t2 where t1.createdDate = t2.createdDate;
 
 drop table t1, t2;
 
+#
+# Bug #38005 Partitions: error with insert select
+#
+
+create table t1 (s1 int) partition by hash(s1) partitions 2;
+create index i on t1 (s1);
+insert into t1 values (1);
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1 order by s1 desc;
+select * from t1;
+drop table t1;
+
+create table t1 (s1 int) partition by range(s1) 
+        (partition pa1 values less than (10),
+         partition pa2 values less than MAXVALUE);
+create index i on t1 (s1);
+insert into t1 values (1);
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1 order by s1 desc;
+select * from t1;
+drop table t1;
+
+create table t1 (s1 int) partition by range(s1) 
+        (partition pa1 values less than (10),
+         partition pa2 values less than MAXVALUE);
+create index i on t1 (s1);
+insert into t1 values (20);
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1 order by s1 desc;
+select * from t1;
+drop table t1;
+
+create table t1 (s1 int) partition by range(s1) 
+        (partition pa1 values less than (10),
+         partition pa2 values less than MAXVALUE);
+create index i on t1 (s1);
+insert into t1 values (1), (2), (3), (4), (5), (6), (7), (8);
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1;
+insert into t1 select s1 from t1 order by s1 desc;
+insert into t1 select s1 from t1 where s1=3;
+select count(*) from t1;
+drop table t1;
+
 --echo End of 5.1 tests