ALTER TABLE table ADD COLUMN column_name [{INTEGER|INT|BIGINT|FLOAT|BOOL|MULTI|MULTI64|JSON|STRING|TIMESTAMP|TEXT [INDEXED [ATTRIBUTE]]}] [engine='columnar']
ALTER TABLE table DROP COLUMN column_nameIt supports adding one field at a time for RT tables. Supported data types are:
int- integer attributetimestamp- timestamp attributebigint- big integer attributefloat- float attributebool- boolean attributemulti- multi-valued integer attributemulti64- multi-valued bigint attributejson- json attributestring/text attribute/string attribute- string attributetext/text indexed stored/string indexed stored- full-text indexed field with original value stored in docstoretext indexed/string indexed- full-text indexed field, indexed only (the original value is not stored in docstore)text indexed attribute/string indexed attribute- full text indexed field + string attribute (not storing the original value in docstore)text stored/string stored- the value will be only stored in docstore, not full-text indexed, not a string attribute- adding
engine='columnar'to any attribute (except for json) will make it stored in the columnar storage
- ❗It's recommended to backup table files before
ALTERing it to avoid data corruption in case of a sudden power interruption or other similar issues. - Querying a table is impossible while a column is being added.
- Newly created attribute's values are set to 0.
ALTERwill not work for distributed tables and tables without any attributes.DROP COLUMNwill fail if a table has only one field.- When dropping a field which is both a full-text field and a string attribute the first
ALTER DROPdrops the attribute, the second one drops the full-text field. - Adding/dropping full-text field is only supported in the RT mode.
- Example
Example
📋
mysql> desc rt;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| group_id | uint |
| date_added | timestamp |
+------------+-----------+
mysql> alter table rt add column test integer;
mysql> desc rt;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| group_id | uint |
| date_added | timestamp |
| test | uint |
+------------+-----------+
mysql> alter table rt drop column group_id;
mysql> desc rt;
+------------+-----------+
| Field | Type |
+------------+-----------+
| id | bigint |
| text | field |
| date_added | timestamp |
| test | uint |
+------------+-----------+
mysql> alter table rt add column title text indexed;
mysql> desc rt;
+------------+-----------+------------+
| Field | Type | Properties |
+------------+-----------+------------+
| id | bigint | |
| text | text | indexed |
| title | text | indexed |
| date_added | timestamp | |
| test | uint | |
+------------+-----------+------------+
mysql> alter table rt add column title text attribute;
mysql> desc rt;
+------------+-----------+------------+
| Field | Type | Properties |
+------------+-----------+------------+
| id | bigint | |
| text | text | indexed |
| title | text | indexed |
| date_added | timestamp | |
| test | uint | |
| title | string | |
+------------+-----------+------------+
mysql> alter table rt drop column title;
mysql> desc rt;
+------------+-----------+------------+
| Field | Type | Properties |
+------------+-----------+------------+
| id | bigint | |
| text | text | indexed |
| title | text | indexed |
| date_added | timestamp | |
| test | uint | |
+------------+-----------+------------+
mysql> alter table rt drop column title;
mysql> desc rt;
+------------+-----------+------------+
| Field | Type | Properties |
+------------+-----------+------------+
| id | bigint | |
| text | text | indexed |
| date_added | timestamp | |
| test | uint | |
+------------+-----------+------------+ALTER TABLE table ft_setting='value'[, ft_setting2='value']You can also use ALTER to modify full-text settings of your table in the RT mode. Just remember that it doesn't affect existing documents, it only affects new ones. Take a look at the example where we:
- create a table with a full-text field and
charset_tablethat allows only 3 searchable characters:a,bandc. - then we insert document 'abcd' and find it by query
abcd, thedjust gets ignored since it's not in thecharset_tablearray - then we understand, that we want
dto be searchable too, so we add it with help ofALTER - but the same query
where match('abcd')still says it searched byabc, because the existing document remembers previous contents ofcharset_table - then we add another document
abcdand search byabcdagain - now it finds the both documents and
show metasays it used two keywords:abc(to find the old document) andabcd(for the new one).
- Example
Example
📋
mysql> create table rt(title text) charset_table='a,b,c';
mysql> insert into rt(title) values('abcd');
mysql> select * from rt where match('abcd');
+---------------------+-------+
| id | title |
+---------------------+-------+
| 1514630637682688054 | abcd |
+---------------------+-------+
mysql> show meta;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| total | 1 |
| total_found | 1 |
| time | 0.000 |
| keyword[0] | abc |
| docs[0] | 1 |
| hits[0] | 1 |
+---------------+-------+
mysql> alter table rt charset_table='a,b,c,d';
mysql> select * from rt where match('abcd');
+---------------------+-------+
| id | title |
+---------------------+-------+
| 1514630637682688054 | abcd |
+---------------------+-------+
mysql> show meta
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| total | 1 |
| total_found | 1 |
| time | 0.000 |
| keyword[0] | abc |
| docs[0] | 1 |
| hits[0] | 1 |
+---------------+-------+
mysql> insert into rt(title) values('abcd');
mysql> select * from rt where match('abcd');
+---------------------+-------+
| id | title |
+---------------------+-------+
| 1514630637682688055 | abcd |
| 1514630637682688054 | abcd |
+---------------------+-------+
mysql> show meta;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| total | 2 |
| total_found | 2 |
| time | 0.000 |
| keyword[0] | abc |
| docs[0] | 1 |
| hits[0] | 1 |
| keyword[1] | abcd |
| docs[1] | 1 |
| hits[1] | 1 |
+---------------+-------+ALTER TABLE table RECONFIGUREALTER can also reconfigure an RT table in the plain mode, so that new tokenization, morphology and other text processing settings from the configuration file take effect for new documents. Note, that the existing document will be left intact. Internally, it forcibly saves the current RAM chunk as a new disk chunk and adjusts the table header, so that new documents are tokenized using the updated full-text settings.
- Example
Example
📋
mysql> show table rt settings;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| settings | |
+---------------+-------+
1 row in set (0.00 sec)
mysql> alter table rt reconfigure;
Query OK, 0 rows affected (0.00 sec)
mysql> show table rt settings;
+---------------+----------------------+
| Variable_name | Value |
+---------------+----------------------+
| settings | morphology = stem_en |
+---------------+----------------------+
1 row in set (0.00 sec)ALTER TABLE table REBUILD SECONDARYALTER can also be used to rebuild secondary indexes in a given table. Sometimes a secondary index can be disabled for the whole table or for one/multiple attributes in it:
- On
UPDATEof an attribute: in this case its secondary index gets disabled. - In case Manticore loads a table with old formatted secondary indexes: in this case secondary indexes will be disabled for the whole table.
ALTER TABLE table REBUILD SECONDARY rebuilds secondary indexes from attribute data and enables them again.
- Example
Example
📋
ALTER TABLE rt REBUILD SECONDARY;Response
Query OK, 0 rows affected (0.00 sec)