7 files changed, 116 insertions, 1 deletions
diff --git a/mysql-test/r/ctype_utf8.result b/mysql-test/r/ctype_utf8.result
index 91dbe853a38..dfc872cc734 100644
--- a/mysql-test/r/ctype_utf8.result
+++ b/mysql-test/r/ctype_utf8.result
@@ -5804,5 +5804,21 @@ c0	c1	c2	c3	c4
 2012-06-11 15:18:24	2012-06-11 15:18:24	2012-06-11 15:18:24	2012-06-11 15:18:24	2012-06-11 15:18:24
 DROP TABLE t2, t1;
 #
+# MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+#
+SET NAMES utf8;
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8);
+INSERT INTO t1 VALUES (REPEAT('Ａ',100));
+SELECT OCTET_LENGTH(a) FROM t1;
+OCTET_LENGTH(a)
+300
+ALTER TABLE t1 MODIFY a TINYTEXT CHARACTER SET utf8;
+Warnings:
+Warning	1265	Data truncated for column 'a' at row 1
+SELECT OCTET_LENGTH(a),a FROM t1;
+OCTET_LENGTH(a)	a
+255	ＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡＡ
+DROP TABLE t1;
+#
 # End of 5.5 tests
 #
diff --git a/mysql-test/r/ctype_utf8mb4.result b/mysql-test/r/ctype_utf8mb4.result
index 64556308de2..29749d3f07b 100644
--- a/mysql-test/r/ctype_utf8mb4.result
+++ b/mysql-test/r/ctype_utf8mb4.result
@@ -2606,6 +2606,22 @@ Warning	1292	Truncated incorrect INTEGER value: 'a'
 DROP TABLE t1;
 # End of test for Bug#13581962,Bug#14096619
 #
+# MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+#
+SET NAMES utf8mb4;
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8mb4);
+INSERT INTO t1 VALUES (REPEAT('😎',100));
+SELECT OCTET_LENGTH(a) FROM t1;
+OCTET_LENGTH(a)
+400
+ALTER TABLE t1 MODIFY a TINYTEXT CHARACTER SET utf8mb4;
+Warnings:
+Warning	1265	Data truncated for column 'a' at row 1
+SELECT OCTET_LENGTH(a),a FROM t1;
+OCTET_LENGTH(a)	a
+252	😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎😎
+DROP TABLE t1;
+#
 # End of 5.5 tests
 #
 #
diff --git a/mysql-test/r/myisam-blob.result b/mysql-test/r/myisam-blob.result
index 43db7c8badd..6b41a244621 100644
--- a/mysql-test/r/myisam-blob.result
+++ b/mysql-test/r/myisam-blob.result
@@ -29,9 +29,11 @@ select length(data) from t1;
 length(data)
 18874368
 alter table t1 modify data blob;
+Warnings:
+Warning	1265	Data truncated for column 'data' at row 1
 select length(data) from t1;
 length(data)
-0
+65535
 drop table t1;
 CREATE TABLE t1 (data BLOB) ENGINE=myisam;
 INSERT INTO t1 (data) VALUES (NULL);
diff --git a/mysql-test/r/type_blob.result b/mysql-test/r/type_blob.result
index 723efbdcb23..f49b2a7d5ef 100644
--- a/mysql-test/r/type_blob.result
+++ b/mysql-test/r/type_blob.result
@@ -1000,9 +1000,42 @@ COUNT(*)
 DROP FUNCTION f1;
 DROP TABLE t1;
 End of 5.1 tests
+#
+# Start of 5.5 tests
+#
 CREATE TABLE t1 ( f1 blob, f2 blob );
 INSERT INTO t1 VALUES ('','');
 SELECT f1,f2,"found row" FROM t1 WHERE f1 = f2 ;
 f1	f2	found row
 		found row
 DROP TABLE t1;
+#
+# MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+#
+CREATE TABLE t1 (a MEDIUMBLOB);
+INSERT INTO t1 VALUES (REPEAT(0x61,128000));
+SELECT LENGTH(a) FROM t1;
+LENGTH(a)
+128000
+ALTER TABLE t1 MODIFY a BLOB;
+Warnings:
+Warning	1265	Data truncated for column 'a' at row 1
+SELECT LENGTH(a) FROM t1;
+LENGTH(a)
+65535
+DROP TABLE t1;
+CREATE TABLE t1 (a BLOB);
+INSERT INTO t1 VALUES (REPEAT(0x61,65000));
+SELECT LENGTH(a) FROM t1;
+LENGTH(a)
+65000
+ALTER TABLE t1 MODIFY a TINYBLOB;
+Warnings:
+Warning	1265	Data truncated for column 'a' at row 1
+SELECT LENGTH(a) FROM t1;
+LENGTH(a)
+255
+DROP TABLE t1;
+#
+# End of 5.5 tests
+#
diff --git a/mysql-test/t/ctype_utf8.test b/mysql-test/t/ctype_utf8.test
index 8cd70e9261a..fd70292c6c8 100644
--- a/mysql-test/t/ctype_utf8.test
+++ b/mysql-test/t/ctype_utf8.test
@@ -1649,5 +1649,16 @@ SELECT * FROM t2;
 DROP TABLE t2, t1;
 
 --echo #
+--echo # MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+--echo #
+SET NAMES utf8;
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8);
+INSERT INTO t1 VALUES (REPEAT('Ａ',100));
+SELECT OCTET_LENGTH(a) FROM t1;
+ALTER TABLE t1 MODIFY a TINYTEXT CHARACTER SET utf8;
+SELECT OCTET_LENGTH(a),a FROM t1;
+DROP TABLE t1;
+
+--echo #
 --echo # End of 5.5 tests
 --echo #
diff --git a/mysql-test/t/ctype_utf8mb4.test b/mysql-test/t/ctype_utf8mb4.test
index fda20ca0ec5..66f5a3ba5ac 100644
--- a/mysql-test/t/ctype_utf8mb4.test
+++ b/mysql-test/t/ctype_utf8mb4.test
@@ -1827,6 +1827,18 @@ DROP TABLE t1;
 --echo # End of test for Bug#13581962,Bug#14096619
 
 --echo #
+--echo # MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+--echo #
+SET NAMES utf8mb4;
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8mb4);
+INSERT INTO t1 VALUES (REPEAT('😎',100));
+SELECT OCTET_LENGTH(a) FROM t1;
+ALTER TABLE t1 MODIFY a TINYTEXT CHARACTER SET utf8mb4;
+SELECT OCTET_LENGTH(a),a FROM t1;
+DROP TABLE t1;
+
+
+--echo #
 --echo # End of 5.5 tests
 --echo #
 
diff --git a/mysql-test/t/type_blob.test b/mysql-test/t/type_blob.test
index 66dd71d2305..d5f6fc6ed32 100644
--- a/mysql-test/t/type_blob.test
+++ b/mysql-test/t/type_blob.test
@@ -643,6 +643,10 @@ DROP TABLE t1;
 
 --echo End of 5.1 tests
 
+--echo #
+--echo # Start of 5.5 tests
+--echo #
+
 #
 # Problem when comparing blobs #778901
 #
@@ -651,3 +655,24 @@ CREATE TABLE t1 ( f1 blob, f2 blob );
 INSERT INTO t1 VALUES ('','');
 SELECT f1,f2,"found row" FROM t1 WHERE f1 = f2 ;
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-9319 ALTER from a bigger to a smaller blob type truncates too much data
+--echo #
+CREATE TABLE t1 (a MEDIUMBLOB);
+INSERT INTO t1 VALUES (REPEAT(0x61,128000));
+SELECT LENGTH(a) FROM t1;
+ALTER TABLE t1 MODIFY a BLOB;
+SELECT LENGTH(a) FROM t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a BLOB);
+INSERT INTO t1 VALUES (REPEAT(0x61,65000));
+SELECT LENGTH(a) FROM t1;
+ALTER TABLE t1 MODIFY a TINYBLOB;
+SELECT LENGTH(a) FROM t1;
+DROP TABLE t1;
+
+--echo #
+--echo # End of 5.5 tests
+--echo #