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25.6.17.26 The ndbinfo dict_obj_tree Table

The dict_obj_tree table provides a tree-based view of table information from the dict_obj_info table. This is intended primarily for use in testing, but can be useful in visualizing hierarchies of NDB database objects.

The dict_obj_tree table contains the following columns:

  • type

    Type of DICT object; join on dict_obj_types to obtain the name of the object type

  • id

    Object identifier; same as the id column in dict_obj_info

    For Disk Data undo log files and data files, this is the same as the value shown in the LOGFILE_GROUP_NUMBER column of the Information Schema FILES table; for undo log files, it also the same as the value shown for the log_id column in the ndbinfo logbuffers and logspaces tables

  • name

    The fully qualified name of the object; the same as the fq_name column in dict_obj_info

    For a table, this is database_name/def/table_name (the same as its parent_name); for an index of any type, this takes the form NDB$INDEX_index_id_CUSTOM

  • parent_type

    The DICT object type of this object's parent object; join on dict_obj_types to obtain the name of the object type

  • parent_id

    Identifier for this object's parent object; the same as the dict_obj_info table's id column

  • parent_name

    Fully qualified name of this object's parent object; the same as the dict_obj_info table's fq_name column

    For a table, this has the form database_name/def/table_name. For an index, the name is sys/def/table_id/index_name. For a primary key, it is sys/def/table_id/PRIMARY, and for a unique key it is sys/def/table_id/uk_name$unique

  • root_type

    The DICT object type of the root object; join on dict_obj_types to obtain the name of the object type

  • root_id

    Identifier for the root object; the same as the dict_obj_info table's id column

  • root_name

    Fully qualified name of the root object; the same as the dict_obj_info table's fq_name column

  • level

    Level of the object in the hierarchy

  • path

    Complete path to the object in the NDB object hierarchy; objects are separated by a right arrow (represented as ->), starting with the root object on the left

  • indented_name

    The name prefixed with a right arrow (represented as ->) with a number of spaces preceding it that correspond to the object's depth in the hierarchy

The path column is useful for obtaining a complete path to a given NDB database object in a single line, whereas the indented_name column can be used to obtain a tree-like layout of complete hierarchy information for a desired object.

Example: Assuming the existence of a test database and no existing table named t1 in this database, execute the following SQL statement:

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CREATE TABLE test.t1 ( a INT PRIMARY KEY, b INT, UNIQUE KEY(b) ) ENGINE = NDB;

You can obtain the path to the table just created using the query shown here:

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mysql> SELECT path FROM ndbinfo.dict_obj_tree -> WHERE name LIKE 'test%t1'; +-------------+ | path | +-------------+ | test/def/t1 | +-------------+ 1 row in set (0.14 sec)

You can see the paths to all dependent objects of this table using the path to the table as the root name in a query like this one:

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mysql> SELECT path FROM ndbinfo.dict_obj_tree -> WHERE root_name = 'test/def/t1'; +----------------------------------------------------------+ | path | +----------------------------------------------------------+ | test/def/t1 | | test/def/t1 -> sys/def/13/b | | test/def/t1 -> sys/def/13/b -> NDB$INDEX_15_CUSTOM | | test/def/t1 -> sys/def/13/b$unique | | test/def/t1 -> sys/def/13/b$unique -> NDB$INDEX_16_UI | | test/def/t1 -> sys/def/13/PRIMARY | | test/def/t1 -> sys/def/13/PRIMARY -> NDB$INDEX_14_CUSTOM | +----------------------------------------------------------+ 7 rows in set (0.16 sec)

To obtain a hierarchical view of the t1 table with all its dependent objects, execute a query similar to this one which selects the indented name of each object having test/def/t1 as the name of its root object:

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mysql> SELECT indented_name FROM ndbinfo.dict_obj_tree -> WHERE root_name = 'test/def/t1'; +----------------------------+ | indented_name | +----------------------------+ | test/def/t1 | | -> sys/def/13/b | | -> NDB$INDEX_15_CUSTOM | | -> sys/def/13/b$unique | | -> NDB$INDEX_16_UI | | -> sys/def/13/PRIMARY | | -> NDB$INDEX_14_CUSTOM | +----------------------------+ 7 rows in set (0.15 sec)

When working with Disk Data tables, note that, in this context, a tablespace or log file group is considered a root object. This means that you must know the name of any tablespace or log file group associated with a given table, or obtain this information from SHOW CREATE TABLE and then querying INFORMATION_SCHEMA.FILES, or similar means as shown here:

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mysql> SHOW CREATE TABLE test.dt_1\G *************************** 1. row *************************** Table: dt_1 Create Table: CREATE TABLE `dt_1` ( `member_id` int unsigned NOT NULL AUTO_INCREMENT, `last_name` varchar(50) NOT NULL, `first_name` varchar(50) NOT NULL, `dob` date NOT NULL, `joined` date NOT NULL, PRIMARY KEY (`member_id`), KEY `last_name` (`last_name`,`first_name`) ) /*!50100 TABLESPACE `ts_1` STORAGE DISK */ ENGINE=ndbcluster DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci 1 row in set (0.00 sec) mysql> SELECT DISTINCT TABLESPACE_NAME, LOGFILE_GROUP_NAME -> FROM INFORMATION_SCHEMA.FILES WHERE TABLESPACE_NAME='ts_1'; +-----------------+--------------------+ | TABLESPACE_NAME | LOGFILE_GROUP_NAME | +-----------------+--------------------+ | ts_1 | lg_1 | +-----------------+--------------------+ 1 row in set (0.00 sec)

Now you can obtain hierarchical information for the table, tablespace, and log file group like this:

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mysql> SELECT indented_name FROM ndbinfo.dict_obj_tree -> WHERE root_name = 'test/def/dt_1'; +----------------------------+ | indented_name | +----------------------------+ | test/def/dt_1 | | -> sys/def/23/last_name | | -> NDB$INDEX_25_CUSTOM | | -> sys/def/23/PRIMARY | | -> NDB$INDEX_24_CUSTOM | +----------------------------+ 5 rows in set (0.15 sec) mysql> SELECT indented_name FROM ndbinfo.dict_obj_tree -> WHERE root_name = 'ts_1'; +-----------------+ | indented_name | +-----------------+ | ts_1 | | -> data_1.dat | | -> data_2.dat | +-----------------+ 3 rows in set (0.17 sec) mysql> SELECT indented_name FROM ndbinfo.dict_obj_tree -> WHERE root_name LIKE 'lg_1'; +-----------------+ | indented_name | +-----------------+ | lg_1 | | -> undo_1.log | | -> undo_2.log | +-----------------+ 3 rows in set (0.16 sec)