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21.5.14.27 The ndbinfo memory_per_fragment Table

The memory_per_fragment table provides information about the usage of memory by individual fragments.

The memory_per_fragment table contains the following columns:

  • fq_name

    Name of this fragment

  • parent_fq_name

    Name of this fragment's parent

  • type

    Type of object; see text for possible values

  • table_id

    Table ID for this table

  • node_id

    Node ID for this node

  • block_instance

    Kernel block instance ID

  • fragment_num

    Fragment ID (number)

  • fixed_elem_alloc_bytes

    Number of bytes allocated for fixed-sized elements

  • fixed_elem_free_bytes

    Free bytes remaining in pages allocated to fixed-size elements

  • fixed_elem_size_bytes

    Length of each fixed-size element in bytes

  • fixed_elem_count

    Number of fixed-size elements

  • fixed_elem_free_count

    Number of free rows for fixed-size elements

  • var_elem_alloc_bytes

    Number of bytes allocated for variable-size elements

  • var_elem_free_bytes

    Free bytes remaining in pages allocated to variable-size elements

  • var_elem_count

    Number of variable-size elements

  • hash_index_alloc_bytes

    Number of bytes allocated to hash indexes

Notes

The type column from this table shows the dictionary object type used for this fragment (Object::Type, in the NDB API), and can take any one of the values shown in the following list:

  • System table

  • User table

  • Unique hash index

  • Hash index

  • Unique ordered index

  • Ordered index

  • Hash index trigger

  • Subscription trigger

  • Read only constraint

  • Index trigger

  • Reorganize trigger

  • Tablespace

  • Log file group

  • Data file

  • Undo file

  • Hash map

  • Foreign key definition

  • Foreign key parent trigger

  • Foreign key child trigger

  • Schema transaction

You can also obtain this list by executing SELECT * FROM ndbinfo.dict_obj_types in the mysql client.

The block_instance column provides the NDB kernel block instance number. You can use this to obtain information about specific threads from the threadblocks table.