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# 7.15.38. `vector_find`

## 7.15.38.1. Summary

Added in version 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

## 7.15.38.2. 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.

## 7.15.38.3. Usage

You need to register `functions/vector` plugin at first:

Execution example:

    plugin_register functions/vector
    # [[0,1337566253.89858,0.000355720520019531],true]

Here is a schema definition and sample data.

Sample schema:

Execution example:

    table_create  Memos TABLE_HASH_KEY ShortText
    # [[0,1337566253.89858,0.000355720520019531],true]
    column_create Memos tags COLUMN_VECTOR ShortText
    # [[0,1337566253.89858,0.000355720520019531],true]

Sample data:

Execution example:

    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"]}
    ]
    # [[0,1337566253.89858,0.000355720520019531],5]

Here is a simple usage of `vector_find` that searches an element in `tags` column and returns the first found element:

Execution example:

    select \
      --table Memos \
      --output_columns 'tags, vector_find(tags, "mroonga")'
    # [
    #   [
    #     0,
    #     1337566253.89858,
    #     0.000355720520019531
    #   ],
    #   [
    #     [
    #       [
    #         5
    #       ],
    #       [
    #         [
    #           "tags",
    #           "ShortText"
    #         ],
    #         [
    #           "vector_find",
    #           null
    #         ]
    #       ],
    #       [
    #         [
    #           "groonga"
    #         ],
    #         null
    #       ],
    #       [
    #         [
    #           "mroonga",
    #           "groonga"
    #         ],
    #         "mroonga"
    #       ],
    #       [
    #         [
    #           "groonga"
    #         ],
    #         null
    #       ],
    #       [
    #         [
    #           "droonga",
    #           "groonga"
    #         ],
    #         null
    #       ],
    #       [
    #         [
    #           "groonga",
    #           "http"
    #         ],
    #         null
    #       ]
    #     ]
    #   ]
    # ]

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:

Execution example:

    select \
      --table Memos \
      --output_columns 'tags, vector_find(tags, "roonga", "@")'
    # [
    #   [
    #     0,
    #     1337566253.89858,
    #     0.000355720520019531
    #   ],
    #   [
    #     [
    #       [
    #         5
    #       ],
    #       [
    #         [
    #           "tags",
    #           "ShortText"
    #         ],
    #         [
    #           "vector_find",
    #           null
    #         ]
    #       ],
    #       [
    #         [
    #           "groonga"
    #         ],
    #         "groonga"
    #       ],
    #       [
    #         [
    #           "mroonga",
    #           "groonga"
    #         ],
    #         "mroonga"
    #       ],
    #       [
    #         [
    #           "groonga"
    #         ],
    #         "groonga"
    #       ],
    #       [
    #         [
    #           "droonga",
    #           "groonga"
    #         ],
    #         "droonga"
    #       ],
    #       [
    #         [
    #           "groonga",
    #           "http"
    #         ],
    #         "groonga"
    #       ]
    #     ]
    #   ]
    # ]

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.

## 7.15.38.4. Parameters

It requires two parameters.

There is an optional parameter.

### 7.15.38.4.1. Required parameters

`vector` and `value` are required.

#### 7.15.38.4.1.1. `vector`

Specifies a vector value to be searched an element.

#### 7.15.38.4.1.2. `value`

Specifies a value to be compared.

### 7.15.38.4.2. Optional parameters

`mode` is optional.

#### 7.15.38.4.2.1. `mode`

Specifies a mode that specifies how to compare each element with value.

See default_mode for available mode names. All mode names except `"NEAR"`, `"SIMILAR"` and `"SUFFIX"` are supported.

The default mode is `"EQUAL"`. Note that default_mode says the default mode is `"MATCH"` but the default mode of `vector_find` is `"EQUAL"`.

## 7.15.38.5. Return value

The matched element on match, `null` otherwise.