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21.5.10.27 The ndbinfo memory_per_fragment Table

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

The following table provides information about the columns in the memory_per_fragment table. For each column, the table shows the name, data type, and a brief description. Additional information can be found in the notes following the table.

Table 21.397 Columns of the memory_per_fragment table

Column Name Type Description
fq_name string Name of this fragment
parent_fq_name string Name of this fragment's parent
type string Type of object; see text for possible values
table_id integer Table ID for this table
node_id integer Node ID for this node
block_instance integer Kernel block instance ID
fragment_num integer Fragment ID (number)
fixed_elem_alloc_bytes integer Number of bytes allocated for fixed-sized elements
fixed_elem_free_bytes integer Free bytes remaining in pages allocated to fixed-size elements
fixed_elem_size_bytes integer Length of each fixed-size element in bytes
fixed_elem_count integer Number of fixed-size elements
fixed_elem_free_count decimal Number of free rows for fixed-size elements
var_elem_alloc_bytes integer Number of bytes allocated for variable-size elements
var_elem_free_bytes integer Free bytes remaining in pages allocated to variable-size elements
var_elem_count integer Number of variable-size elements
hash_index_alloc_bytes integer Number of bytes allocated to hash indexes

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.