ALTER TABLE index {ADD|DROP} COLUMN column_name [{INTEGER|INT|BIGINT|FLOAT|BOOL|MULTI|MULTI64|JSON|STRING|TIMESTAMP}]It supports adding one attribute at a time for both plain and RT indexes. The int, bigint, float, bool, multi-valued, multi-valued 64bit, json and string attribute types are supported. You can add json and string attributes, but you cannot modify their values.
- Querying an index is impossible (because of a write lock) while adding a column.
- Newly created attribute's values are set to 0.
ALTERwill not work for distributed indexes and indexes without any attributes.DROP COLUMNwill fail if an index has only one attribute.
ALTER RTINDEX index RECONFIGUREALTER can also reconfigure an RT index in plain mode, so that new tokenization, morphology, and other text processing settings from the configuration file take effect on the newly INSERT-ed rows, while retaining the existing rows as they were. Internally, it forcibly saves the current RAM chunk as a new disk chunk, and adjusts the index header, so that the new rows are tokenized using the new rules.
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- Example
Example
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mysql> desc plain;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| group_id | uint |
| date_added | timestamp |
+------------+-----------+
4 rows in set (0.01 sec)
mysql> alter table plain add column test integer;
Query OK, 0 rows affected (0.04 sec)
mysql> desc plain;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| group_id | uint |
| date_added | timestamp |
| test | uint |
+------------+-----------+
5 rows in set (0.00 sec)
mysql> alter table plain drop column group_id;
Query OK, 0 rows affected (0.01 sec)
mysql> desc plain;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| date_added | timestamp |
| test | uint |
+------------+-----------+
4 rows in set (0.00 sec)