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_name
ALTER TABLE table MODIFY COLUMN column_name bigint
This feature only supports adding one field at a time for RT tables or the expansion of an int
column to bigint
. The 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
ALTER
ing 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.
ALTER
will not work for distributed tables and tables without any attributes.- You can't delete the
id
column. - When dropping a field which is both a full-text field and a string attribute the first
ALTER DROP
drops the attribute, the second one drops the full-text field. - Adding/dropping full-text field is only supported in the RT mode.
- 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 use ALTER
to modify the full-text settings of your table in RT mode. However, it only affects new documents and not existing ones.
Example:
- create a table with a full-text field and
charset_table
that allows only 3 searchable characters:a
,b
andc
. - then we insert document 'abcd' and find it by query
abcd
, thed
just gets ignored since it's not in thecharset_table
array - then we understand, that we want
d
to 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
abcd
and search byabcd
again - now it finds the both documents and
show meta
says it used two keywords:abc
(to find the old document) andabcd
(for the new one).
- 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 |
+---------------+-------+
You can change the name of a real-time table in RT mode.
ALTER TABLE table_name RENAME new_table_name;
- Example
ALTER TABLE table_name RENAME new_table_name;
Query OK, 0 rows affected (0.00 sec)
ALTER TABLE table RECONFIGURE
ALTER
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
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 SECONDARY
You can also use ALTER
to rebuild secondary indexes in a given table. Sometimes, a secondary index can be disabled for the entire table or for one or multiple attributes within the table:
- When an attribute is updated, its secondary index gets disabled.
- If Manticore loads a table with an old version of secondary indexes that is no longer supported, the secondary indexes will be disabled for the entire table.
ALTER TABLE table REBUILD SECONDARY
rebuilds secondary indexes from attribute data and enables them again.
Additionally, an old version of secondary indexes may be supported but will lack certain features. REBUILD SECONDARY
can be used to update secondary indexes.
- Example
ALTER TABLE rt REBUILD SECONDARY;
Query OK, 0 rows affected (0.00 sec)
To change the list of local or remote nodes in a distributed table, follow the same syntax you used to create the table. Just replace CREATE
with ALTER
in the command and remove type='distributed'
:
ALTER TABLE `distr_table_name` [[local='local_index_name'], [agent='host:port:remote_index'] ... ]
- Example
ALTER TABLE local_dist local='index1' local='index2' agent='127.0.0.1:9312:remote_index';
Returns the absolute value of the argument.
Returns the arctangent function of two arguments, expressed in radians.
BITDOT(mask, w0, w1, ...)
returns the sum of products of each bit of a mask multiplied by its weight. bit0*w0 + bit1*w1 + ...
Returns the smallest integer value greater than or equal to the argument.
Returns the cosine of the argument.
Returns the CRC32 value of a string argument.
Returns the exponent of the argument (e=2.718... to the power of the argument).
Returns the N-th Fibonacci number, where N is the integer argument. That is, arguments of 0 and up will generate the values 0, 1, 1, 2, 3, 5, 8, 13 and so on. Note that the computations are done using 32-bit integer math and thus numbers 48th and up will be returned modulo 2^32.
Returns the largest integer value lesser than or equal to the argument.
GREATEST(attr_json.some_array)
function takes a JSON array as the argument, and returns the greatest value in that array. Also works for MVA.
Returns the result of an integer division of the first argument by the second argument. Both arguments must be of an integer type.
LEAST(attr_json.some_array)
function takes a JSON array as the argument, and returns the least value in that array. Also works for MVA.
Returns the natural logarithm of the argument (with the base of e=2.718...).
Returns the common logarithm of the argument (with the base of 10).
Returns the binary logarithm of the argument (with the base of 2).
Returns the larger of two arguments.
Returns the smaller of two arguments.
Returns the first argument raised to the power of the second argument.
Returns a random float between 0 and 1. It can optionally accept a seed
, which can be a constant integer or an integer attribute's name.
If you use a seed
, keep in mind that it resets rand()
's starting point separately for each plain table, RT disk, RAM chunk, or pseudo shard. Therefore, queries to a distributed table in any form can return multiple identical random values.
Returns the sine of the argument.
Returns the square root of the argument.