ha_innodb.cc:

  Add comment about how to modify InnoDB to deal with partial-field prefixes of key value in the future


sql/ha_innodb.cc:
  Add comment about how to modify InnoDB to deal with partial-field prefixes of key value in the future

1 files changed, 8 insertions, 2 deletions

diff --git a/sql/ha_innodb.cc b/sql/ha_innodb.cc
index 3ceb5cbeb36..b1f1911858d 100644
--- a/sql/ha_innodb.cc
+++ b/sql/ha_innodb.cc
@@ -2257,13 +2257,19 @@ convert_search_mode_to_innobase(
 		case HA_READ_PREFIX:		return(PAGE_CUR_GE);
 	        case HA_READ_PREFIX_LAST:       return(PAGE_CUR_LE);
 		  /* In MySQL-4.0 HA_READ_PREFIX and HA_READ_PREFIX_LAST always
-		  pass a complete-field-prefix of a key value as the search
+		  pass a complete-field prefix of a key value as the search
 		  tuple. I.e., it is not allowed that the last field would
 		  just contain n first bytes of the full field value.
 		  MySQL uses a 'padding' trick to convert LIKE 'abc%'
 		  type queries so that it can use as a search tuple
 		  a complete-field-prefix of a key value. Thus, the InnoDB
-		  search mode PAGE_CUR_LE_OR_EXTENDS is never used. */
+		  search mode PAGE_CUR_LE_OR_EXTENDS is never used.
+		  TODO: when/if MySQL starts to use also partial-field
+		  prefixes, we have to deal with stripping of spaces
+		  and comparison of non-latin1 char type fields in
+		  innobase_mysql_cmp() to get PAGE_CUR_LE_OR_EXTENDS to
+		  work correctly. */
+
 		default:			assert(0);
 	}