Kouhei Sutou
null+****@clear*****
Thu Sep 10 18:00:37 JST 2015
Kouhei Sutou 2015-09-10 18:00:37 +0900 (Thu, 10 Sep 2015) New Revision: b1535f4f7b4567742af3f7a4e974c9aaeb66eb86 https://github.com/groonga/groonga/commit/b1535f4f7b4567742af3f7a4e974c9aaeb66eb86 Message: doc: update table_remove Modified files: doc/source/reference/commands/table_remove.rst Modified: doc/source/reference/commands/table_remove.rst (+207 -16) =================================================================== --- doc/source/reference/commands/table_remove.rst 2015-09-10 17:38:20 +0900 (7d417f7) +++ doc/source/reference/commands/table_remove.rst 2015-09-10 18:00:37 +0900 (eba8db7) @@ -2,46 +2,237 @@ .. highlightlang:: none +.. groonga-command +.. database: commands_table_remove + ``table_remove`` ================ Summary ------- -table_remove - テーブルの削除 - -groonga組込コマンドの一つであるtable_removeについて説明します。組込コマンドは、groonga実行ファイルの引数、標準入力、またはソケット経由でgroongaサーバにリクエストを送信することによって実行します。 - -table_removeはテーブルと定義されているカラムを削除します。カラムに付随するインデックスも再帰的に削除されます。 +``table_remove`` removes a table and its columns. If there are one or +more indexes against key of the table and its columns, they are also +removed. Syntax ------ -:: - table_remove name +This command takes only one required parameter:: + + table_remove name + +.. _table-remove-usage: Usage ----- -:: - table_remove Entry +You just specify table name that you want to remove. ``table_remove`` +removes the table and its columns. If the table and its columns are +indexed, all index columns for the table and its columns are also +removed. + +This section describes about the followings: + + * Basic usage + * Unremovable cases + * Decreases used resources + +.. _table-remove-basic-usage: + +Basic usage +^^^^^^^^^^^ + +Let's think about the following case: + + * There is one table ``Entries``. + * ``Entries`` table has some columns. + * ``Entries`` table's key is indexed. + * A column of ``Entries`` is indexed. + +Here are commands that create ``Entries`` table: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_create_entries_table.log +.. table_create Entries TABLE_HASH_KEY UInt32 +.. column_create Entries title COLUMN_SCALAR ShortText +.. column_create Entries content COLUMN_SCALAR Text + +Here are commands that create an index for ``Entries`` table's key: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_create_index_for_entries_table.log +.. table_create EntryKeys TABLE_HASH_KEY UInt32 +.. column_create EntryKeys key_index COLUMN_INDEX Entries _key + +Here are commands that create an index for ``Entries`` table's column: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_create_index_for_entries_table_column.log +.. table_create Terms TABLE_PAT_KEY ShortText \ +.. --default_tokenizer TokenBigram \ +.. --normalizer NormalizerAuto +.. column_create Terms content_index COLUMN_INDEX Entries content + +Let's confirm the current schema before running ``table_remove``: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_dump_before_table_remove.log +.. dump + +If you remove ``Entries`` table, the following tables and columns are +removed: + + * ``Entries`` + * ``Entries.title`` + * ``Entries.context`` + * ``EntryKeys.key_index`` + * ``Terms.content_index`` + +The following tables (lexicons) aren't removed: + + * ``EntryKeys`` + * ``Terms`` + +Let's run ``table_remove``: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_table_remove.log +.. table_remove Entries + +Here is schema after ``table_remove``. Only ``EntryKeys`` and +``Terms`` exist: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/basic_usage_dump_after_table_remove.log +.. dump + +.. _table-remove-unremovable-cases: + +Unremovable cases +^^^^^^^^^^^^^^^^^ + +There are some unremovable cases: + + * One or more tables use the table as key type. + * One or more columns use the table as value type. + +Both cases blocks dangling references. If the table is referenced as +type and the table is removed, tables and columns that refer the table +are broken. - [true] +If the target table satisfies one of them, ``table_remove`` is +failed. The target table and its columns aren't removed. + +Here is an example for the table is used as key type case. + +The following commands create a table to be removed and a table that +uses the table to be removed as key type: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_key_type_create.log +.. table_create ReferencedByTable TABLE_HASH_KEY ShortText +.. table_create ReferenceTable TABLE_HASH_KEY ReferencedByTable + +``table_remove`` against ``ReferencedByTable`` is failed: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_key_type_remove_fail.log +.. table_remove ReferencedByTable + +You need to remove ``ReferenceTable`` before you remove +``ReferencedByTable``: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_key_type_remove_success.log +.. table_remove ReferenceTable +.. table_remove ReferencedByTable + +Here is an example for the table is used as value type case. + +The following commands create a table to be removed and a column that +uses the table to be removed as value type: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_value_type_create.log +.. table_create ReferencedByColumn TABLE_HASH_KEY ShortText +.. table_create Table TABLE_NO_KEY +.. column_create Table reference_column COLUMN_SCALAR ReferencedByColumn + +``table_remove`` against ``ReferencedByColumn`` is failed: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_value_type_remove_fail.log +.. table_remove ReferencedByColumn + +You need to remove ``Table.reference_column`` before you remove +``ReferencedByColumn``: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/unremovable_cases_value_type_remove_success.log +.. column_remove Table reference_column +.. table_remove ReferencedByColumn + +Decreases used resources +^^^^^^^^^^^^^^^^^^^^^^^^ + +``table_remove`` opens all tables and columns in database to check +:ref:`table-remove-unremovable-cases`. + +If you have many tables and columns, ``table_remove`` may use many +resources. There is a workaround to avoid the case. + +``table_remove`` closes temporary opened tables and columns for +checking when the max number of threads is ``1``. + +You can confirm and change the current max number of threads by +:doc:`thread_limit`. + +.. groonga-command +.. thread_limit 4 + +The feature is used in the following case: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/decreases_used_resources_close_temporary_opened_objects.log +.. table_create Entries TABLE_NO_KEY +.. thread_limit 1 +.. table_remove Entries + +The feature isn't used in the following case: + +.. groonga-command +.. include:: ../../example/reference/commands/table_remove/decreases_used_resources_close_temporary_opened_objects.log +.. table_create Entries TABLE_NO_KEY +.. thread_limit 2 +.. table_remove Entries Parameters ---------- +This section describes all parameters. + +Required parameters +^^^^^^^^^^^^^^^^^^^ + +There is only one required parameters. + +.. _table-remove-name: + ``name`` - 削除対象のカラムが定義されているテーブルの名前を指定します。 +"""""""" + +Specifies the table name to be removed. + +See :ref:`table-remove-usage` how to use this parameter. Return value ------------ -:: - - [成功かどうかのフラグ] +The command returns ``true`` as body on success such as:: -``成功かどうかのフラグ`` + [HEADER, true] - エラーが生じなかった場合にはtrue、エラーが生じた場合にはfalseを返す。 +If the command fails, error details are in ``HEADER``. +See :doc:`/reference/command/output_format` for ``HEADER``. -------------- next part -------------- HTML����������������������������...다운로드
