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.. -*- rst -*-
.. groonga-command
.. database: functions_vector_find
``vector_find``
===============
Summary
-------
.. versionadded:: 8.0.4
It returns the first element that matches the given condition from the
given vector. If no element is found, it returns ``null``.
You can use not only equal condition but also less than condition,
prefix equal condition and so on.
To enable this function, register ``functions/vector`` plugin by
the following command::
plugin_register functions/vector
.. _vector-find-syntax:
Syntax
------
``vector_find`` has two or three parameters::
vector_find(vector, value)
vector_find(vector, value, mode)
If you omit the third argument, each element in the ``vector`` is
compared with ``value`` by equality comparison.
.. _vector-find-usage:
Usage
-----
You need to register ``functions/vector`` plugin at first:
.. groonga-command
.. include:: ../../example/reference/functions/vector_find/usage_register.log
.. plugin_register functions/vector
Here is a schema definition and sample data.
Sample schema:
.. groonga-command
.. include:: ../../example/reference/functions/vector_find/usage_setup_schema.log
.. table_create Memos TABLE_HASH_KEY ShortText
.. column_create Memos tags COLUMN_VECTOR ShortText
Sample data:
.. groonga-command
.. include:: ../../example/reference/functions/vector_find/usage_setup_data.log
.. load --table Memos
.. [
.. {"_key": "Groonga is fast", "tags": ["groonga"]},
.. {"_key": "Mroonga is fast", "tags": ["mroonga", "groonga"]},
.. {"_key": "Groonga is very good!", "tags": ["groonga"]},
.. {"_key": "Droonga is fast", "tags": ["droonga", "groonga"]},
.. {"_key": "Groonga is a HTTP server", "tags": ["groonga", "http"]}
.. ]
Here is a simple usage of ``vector_find`` that searches an element in
``tags`` column and returns the first found element:
.. groonga-command
.. include:: ../../example/reference/functions/vector_find/usage_find.log
.. select \
.. --table Memos \
.. --output_columns 'tags, vector_find(tags, "mroonga")'
It returns ``"mroonga"`` when the ``tags`` column value includes
``"mroonga"`` element. It returns ``null`` otherwise.
You can customize how to compare with each value by the third
argument. Here is a usage to use full text search to find an element:
.. groonga-command
.. include:: ../../example/reference/functions/vector_find/usage_find_mode.log
.. select \
.. --table Memos \
.. --output_columns 'tags, vector_find(tags, "roonga", "@")'
It returns ``"groonga"``, ``"mroonga"`` or ``"droonga"`` when the
``tags`` column value includes one of them. The returned value is the
first found element. For example, ``"droonga"`` is returned for
``["droonga", "groonga"]``. ``"groonga"`` isn't returned because the
first element ``"droonga"`` is found before the second element
``"groonga"`` is searched.
It returns ``null`` when ``tags`` column value doesn't include them.
.. _vector-find-parameters:
Parameters
----------
It requires two parameters.
There is an optional parameter.
.. _vector-find-required-parameters:
Required parameters
^^^^^^^^^^^^^^^^^^^
``vector`` and ``value`` are required.
.. _vector-find-vector:
``vector``
""""""""""
Specifies a vector value to be searched an element.
.. _vector-find-value:
``value``
"""""""""
Specifies a value to be compared.
.. _vector-find-optional-parameters:
Optional parameters
^^^^^^^^^^^^^^^^^^^
``mode`` is optional.
.. _vector-find-mode:
``mode``
""""""""
Specifies a mode that specifies how to compare each element with
:ref:`vector-find-value`.
See :ref:`query-default-mode` for available mode names. All mode names
except ``"NEAR"``, ``"SIMILAR"`` and ``"SUFFIX"`` are supported.
The default mode is ``"EQUAL"``. Note that :ref:`query-default-mode`
says the default mode is ``"MATCH"`` but the default mode of
``vector_find`` is ``"EQUAL"``.
Return value
------------
The matched element on match, ``null`` otherwise.
|
