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.. -*- rst -*-
.. groonga-command
.. database: functions_in_records
``in_records``
==============
Summary
-------
.. versionadded:: 7.0.2
You can use ``in_records`` for using an existing table as condition patterns. Each record in the existing table is treated as a condition pattern.
You may be able to reduce multiple queries to only one query by ``in_records``.
``in_records`` is similar to :doc:`sub_filter`. Here are differences of them:
* ``sub_filter`` requires a reference column to condition table but ``in_records`` doesn't require.
* ``sub_filter`` requires an index column for the reference column but ``in_records`` doesn't require.
* ``sub_filter`` can use all logical operations but ``in_records`` can use only AND logical operation in one pattern.
* ``sub_filter`` can use only the value of one reference column for condition but ``in_records`` can use one or more values for condition. You can use multiple columns, functions and so on for multiple values.
* ``sub_filter`` uses index search but ``in_records`` uses sequential search.
.. _in-records-syntax:
Syntax
------
``in_records`` has four or more parameters::
in_records(condition_table,
value1, mode1, condition_column_name1,
...,
valueN, modeN, condition_column_nameN)
.. _in-records-usage:
Usage
-----
Here is a schema definition and sample data.
Sample schema:
.. groonga-command
.. include:: ../../example/reference/functions/in_records/usage_setup_schema.log
.. table_create Tags TABLE_PAT_KEY ShortText
..
.. table_create Conditions TABLE_PAT_KEY ShortText
.. column_create Conditions user_pattern COLUMN_SCALAR ShortText
.. column_create Conditions tag COLUMN_SCALAR Tags
.. column_create Conditions max_length COLUMN_SCALAR UInt32
..
.. table_create Memos TABLE_HASH_KEY ShortText
.. column_create Memos user COLUMN_SCALAR ShortText
.. column_create Memos tag COLUMN_SCALAR Tags
Sample data:
.. groonga-command
.. include:: ../../example/reference/functions/in_records/usage_setup_data.log
.. load --table Memos
.. [
.. {"_key": "Groonga is fast", "user": "alice", "tag": "groonga"},
.. {"_key": "Mroonga is fast", "user": "alice", "tag": "mroonga"},
.. {"_key": "Groonga is very good!", "user": "alice", "tag": "groonga"},
.. {"_key": "Droonga is fast", "user": "david", "tag": "droonga"},
.. {"_key": "Groonga is a HTTP server", "user": "david", "tag": "groonga"}
.. ]
Sample conditions:
.. groonga-command
.. include:: ../../example/reference/functions/in_records/usage_setup_conditions.log
.. load --table Conditions
.. [
.. {"_key": "lic + groonga", "user_pattern": "lic", "tag": "groonga", max_length: 20},
.. {"_key": "dav + droonga", "user_pattern": "dav", "tag": "droonga", max_length: 50}
.. ]
Here is a simple usage of ``in_records`` that searches by records in ``Conditions`` table. Each record is used as a condition:
.. groonga-command
.. include:: ../../example/reference/functions/in_records/usage_search.log
.. plugin_register functions/string
.. select \
.. --table Memos \
.. --filter 'in_records(Conditions, \
.. user, "@", "user_pattern", \
.. tag, "==", "tag", \
.. string_length(_key), "<=", "max_length")' \
.. --sort_by _id \
.. --output_columns _key,user,tag
The ``filter`` tries the following three conditions for each record:
* ``Memos.user`` matches (``@``) ``Conditions.user_pattern``.
* ``Memos.tag`` equals (``==``) ``Conditions.tag``.
* The number of characters in ``Memos._key`` is less than or equals to ``Conditions.max_length``.
If at least one record in ``Conditions`` table returns true for the all three conditions, the record in ``Memos`` is matched.
The first record in ``Conditions`` table use the following conditions:
* ``Memos.user`` has ``"lic"`` substring.
* ``Memos.tag`` is ``"groonga"``.
* The number of characters in ``Memos._key`` is less than or equals to ``20``.
This condition matches the following records:
* ``{"_key": "Groonga is fast", "user": "alice", "tag": "groonga"}``
The second record in ``Conditions`` table use the following conditions:
* ``Memos.user`` has ``"dav"`` substring.
* ``Memos.tag`` is ``"droonga"``.
* The number of characters in ``Memos._key`` is less than or equals to ``50``.
This condition matches the following records:
* ``{"_key": "Droonga is fast", "user": "david", "tag": "droonga"}``
The result has the all above records.
.. _in-records-parameters:
Parameters
----------
``in_records`` requires four or more parameters.
.. _in-records-required-parameters:
Required parameters
^^^^^^^^^^^^^^^^^^^
``condition_table`` and tuples of ``value``, ``mode_name`` and ``condition_column_name`` are required. You can specify multiple tuples of ``value``, ``mode_name`` and ``condition_column_name``
.. _in-records-condition-table:
``condition_table``
"""""""""""""""""""
Specifies a table that has conditions as its records.
.. _in-records-value:
``value``
^^^^^^^^^
Specifies a value to be compared.
.. _in-records-mode-name:
``mode_name``
^^^^^^^^^^^^^
Specifies a mode name that specifies how to compare :ref:`in-records-value` with a value of :ref:`in-records-condition-column-name`.
See :ref:`query-default-mode` for available mode names. All mode names
except ``"NEAR"``, ``"SIMILAR"`` and ``"SUFFIX"`` are supported.
.. _in-records-condition-column-name:
``condition_column_name``
^^^^^^^^^^^^^^^^^^^^^^^^^
Specifies a column name of :ref:`in-records-condition-table` to be used as condition.
.. _in-records-optional-parameters:
Optional parameter
^^^^^^^^^^^^^^^^^^
There are no optional parameter.
Return value
------------
``in_records`` returns whether the record is matched one of records of the specified condition table or not.
If the record is matched, it returns ``true``. Otherwise, it returns ``false``.
|
