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This patch implements engine independent unique hash index.
Usage:- Unique HASH index can be created automatically for blob/varchar/test column whose key
length > handler->max_key_length()
or it can be explicitly specified.
Automatic Creation:-
Create TABLE t1 (a blob unique);
Explicit Creation:-
Create TABLE t1 (a int , unique(a) using HASH);
Internal KEY_PART Representations:-
Long unique key_info will have 2 representations.
(lets understand this with an example create table t1(a blob, b blob , unique(a, b)); )
1. User Given Representation:- key_info->key_part array will be similar to what user has defined.
So in case of example it will have 2 key_parts (a, b)
2. Storage Engine Representation:- In this case there will be only one key_part and it will point to
HASH_FIELD. This key_part will be always after user defined key_parts.
So:- User Given Representation [a] [b] [hash_key_part]
key_info->key_part ----^
Storage Engine Representation [a] [b] [hash_key_part]
key_info->key_part ------------^
Table->s->key_info will have User Given Representation, While table->key_info will have Storage Engine
Representation.Representation can be changed into each other by calling re/setup_keyinfo_hash function.
Working:-
1. So when user specifies HASH_INDEX or key_length is > handler->max_key_length(), In mysql_prepare_create_table
One extra vfield is added (for each long unique key). And key_info->algorithm is set to HA_KEY_ALG_LONG_HASH.
2. In init_from_binary_frm_image values for hash_keypart is set (like fieldnr , field and flags)
3. In parse_vcol_defs, HASH_FIELD->vcol_info is created. Item_func_hash is used with list of Item_fields,
When Explicit length is given by user then Item_left is used to concatenate Item_field values.
4. In ha_write_row/ha_update_row check_duplicate_long_entry_key is called which will create the hash key from
table->record[0] and then call ha_index_read_map , if we found duplicated hash , we will compare the result
field by field.
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| .. | ||
| doc | ||
| mysql-test | ||
| PerconaFT | ||
| tests | ||
| tools | ||
| CMakeLists.txt | ||
| ha_tokudb.cc | ||
| ha_tokudb.h | ||
| ha_tokudb_admin.cc | ||
| ha_tokudb_alter_55.cc | ||
| ha_tokudb_alter_56.cc | ||
| ha_tokudb_alter_common.cc | ||
| ha_tokudb_mrr_maria.cc | ||
| ha_tokudb_mrr_mysql.cc | ||
| ha_tokudb_update.cc | ||
| hatoku_cmp.cc | ||
| hatoku_cmp.h | ||
| hatoku_defines.h | ||
| hatoku_hton.cc | ||
| hatoku_hton.h | ||
| tokudb.cnf.in | ||
| tokudb.conf.in | ||
| tokudb_background.cc | ||
| tokudb_background.h | ||
| tokudb_buffer.h | ||
| tokudb_card.h | ||
| tokudb_debug.h | ||
| tokudb_dir_cmd.cc | ||
| tokudb_dir_cmd.h | ||
| tokudb_information_schema.cc | ||
| tokudb_information_schema.h | ||
| tokudb_math.h | ||
| tokudb_memory.h | ||
| tokudb_status.h | ||
| tokudb_sysvars.cc | ||
| tokudb_sysvars.h | ||
| tokudb_thread.cc | ||
| tokudb_thread.h | ||
| tokudb_time.h | ||
| tokudb_txn.h | ||
| tokudb_update_fun.cc | ||
| tokudb_vlq.h | ||