diff options
Diffstat (limited to 'storage/innobase/include/dict0mem.h')
| -rw-r--r-- | storage/innobase/include/dict0mem.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/storage/innobase/include/dict0mem.h b/storage/innobase/include/dict0mem.h index a23f89954a4..647035c2fff 100644 --- a/storage/innobase/include/dict0mem.h +++ b/storage/innobase/include/dict0mem.h @@ -158,10 +158,13 @@ struct dict_col_struct{ of an index */ }; -/* DICT_MAX_INDEX_COL_LEN is measured in bytes and is the max index column -length + 1. Starting from 4.1.6, we set it to < 3 * 256, so that one can -create a column prefix index on 255 characters of a TEXT field also in the -UTF-8 charset. In that charset, a character may take at most 3 bytes. */ +/* DICT_MAX_INDEX_COL_LEN is measured in bytes and is the maximum +indexed column length (or indexed prefix length). It is set to 3*256, +so that one can create a column prefix index on 256 characters of a +TEXT or VARCHAR column also in the UTF-8 charset. In that charset, +a character may take at most 3 bytes. +This constant MUST NOT BE CHANGED, or the compatibility of InnoDB data +files would be at risk! */ #define DICT_MAX_INDEX_COL_LEN 768 |