Manually merged

mysql-test/r/cast.result:
  Auto merged
mysql-test/t/func_time.test:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/item_strfunc.cc:
  Auto merged
sql/item_timefunc.cc:
  Auto merged
sql/item_timefunc.h:
  Auto merged
sql/opt_sum.cc:
  Auto merged
sql/structs.h:
  Auto merged

1 files changed, 7 insertions, 1 deletions

diff --git a/sql/structs.h b/sql/structs.h
index 9421ebdc2af..41b5f3b39c5 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -70,7 +70,13 @@ typedef struct st_key_part_info {	/* Info about a key part */
   Field *field;
   uint	offset;				/* offset in record (from 0) */
   uint	null_offset;			/* Offset to null_bit in record */
-  uint16 length;			/* Length of key_part */
+  uint16 length;                        /* Length of keypart value in bytes */
+  /* 
+    Number of bytes required to store the keypart value. This may be
+    different from the "length" field as it also counts
+     - possible NULL-flag byte (see HA_KEY_NULL_LENGTH)
+     - possible HA_KEY_BLOB_LENGTH bytes needed to store actual value length.
+  */
   uint16 store_length;
   uint16 key_type;
   uint16 fieldnr;			/* Fieldnum in UNIREG */