Post push fix for bug#11766249 bug#59316

Partitions can have different ref_length (position data length).
Removed DBUG_ASSERT which crashed debug builds when using
MAX_ROWS on some partitions.

mysql-test/r/partition_not_embedded.result → mysql-test/r/partition_myisam.result

@@ -79,3 +79,12 @@ a
 DROP TABLE t1;
 # Should not be any files left here
 # End of bug#30102 test.
+# Test of post-push fix for bug#11766249/59316
+CREATE TABLE t1 (a INT, b VARCHAR(255), PRIMARY KEY (a))
+ENGINE = MyISAM
+PARTITION BY RANGE (a)
+(PARTITION p0 VALUES LESS THAN (0) MAX_ROWS=100,
+PARTITION p1 VALUES LESS THAN (100) MAX_ROWS=100,
+PARTITION pMax VALUES LESS THAN MAXVALUE);
+INSERT INTO t1 VALUES (1, "Partition p1, first row");
+DROP TABLE t1;

mysql-test/t/partition_not_embedded.test → mysql-test/t/partition_myisam.test

 -- source include/have_partition.inc
--- source include/not_embedded.inc
 --disable_warnings
 DROP TABLE IF EXISTS t1, t2;
 --enable_warnings
@@ -51,3 +50,13 @@ DROP TABLE t1;
 --list_files $MYSQLD_DATADIR/test t1*
 --list_files $MYSQLD_DATADIR/test t2*
 --echo # End of bug#30102 test.
+
+--echo # Test of post-push fix for bug#11766249/59316
+CREATE TABLE t1 (a INT, b VARCHAR(255), PRIMARY KEY (a))
+ENGINE = MyISAM
+PARTITION BY RANGE (a)
+(PARTITION p0 VALUES LESS THAN (0) MAX_ROWS=100,
+ PARTITION p1 VALUES LESS THAN (100) MAX_ROWS=100,
+ PARTITION pMax VALUES LESS THAN MAXVALUE);
+INSERT INTO t1 VALUES (1, "Partition p1, first row");
+DROP TABLE t1;

sql/ha_partition.cc

@@ -2697,7 +2697,7 @@ int ha_partition::open(const char *name, int mode, uint test_if_locked)
                       (PARTITION_ENABLED_TABLE_FLAGS));
   while (*(++file))
   {
-    DBUG_ASSERT(ref_length >= (*file)->ref_length);
+    /* MyISAM can have smaller ref_length for partitions with MAX_ROWS set */
     set_if_bigger(ref_length, ((*file)->ref_length));
     /*
       Verify that all partitions have the same set of table flags.
@@ -3957,12 +3957,15 @@ int ha_partition::rnd_next(uchar *buf)
 void ha_partition::position(const uchar *record)
 {
   handler *file= m_file[m_last_part];
+  uint pad_length;
   DBUG_ENTER("ha_partition::position");
 
   file->position(record);
   int2store(ref, m_last_part);
-  memcpy((ref + PARTITION_BYTES_IN_POS), file->ref,
-	 (ref_length - PARTITION_BYTES_IN_POS));
+  memcpy((ref + PARTITION_BYTES_IN_POS), file->ref, file->ref_length);
+  pad_length= m_ref_length - PARTITION_BYTES_IN_POS - file->ref_length;
+  if (pad_length)
+    memset((ref + PARTITION_BYTES_IN_POS + file->ref_length), 0, pad_length);
 
 #ifdef SUPPORTING_PARTITION_OVER_DIFFERENT_ENGINES
 #ifdef HAVE_purify