DBE_HEAT_MAP

API Description

Returns information such as the last modification time of a row in the target data block based on the input parameters. The information is used to browse the basis for determining cold and hot rows. This API is an O&M API and has no visibility check. That is, if the input CTID is a deleted row, this API still returns the latest status of the current row on the page.

• DBE_HEAT_MAP.ROW_HEAT_MAP

  Obtains information such as the last modification time of a row based on the schema to which the object belongs, data object name, data object partition name, and CTID. The prototype is as follows:

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  DBE_HEAT_MAP.ROW_HEAT_MAP( OWNER IN VARCHAR2, SEGMENT_NAME IN VARCHAR2, PARTITION_NAME IN VARCHAR2 DEFAULT NULL, CTID IN TEXT, V_DEBUG IN BOOL DEFAULT FALSE);

  Table 2 DBE_HEAT_MAP.ROW_HEAT_MAP parameters

  Parameter	Description
  OWNER	Schema to which a data object belongs.
  SEGMENT_NAME	Data object name.
  PARTITION_NAME	Data object partition name. This parameter is optional. The default value is NULL.
  CTID	ctid of the target row, that is, block_id or row_id.
  V_DEBUG	Debugging. Debug logs are recorded.

  Table 3 Output parameters of DBE_HEAT_MAP.ROW_HEAT_MAP

  Parameter	Description
  OWNER	Owner of a data object.
  SEGMENT_NAME	Data object name.
  PARTITION_NAME	Name of a data object partition. This parameter is optional.
  TABLESPACE_NAME	Name of the tablespace to which data belongs.
  FILE_ID	ID of the absolute file to which a row belongs.
  RELATIVE_FNO	ID of the relative file to which a row belongs. (GaussDB does not have this logic. Therefore, the value is the same as the preceding value.)
  CTID	ctid of a row, that is, block_id or row_id.
  WRITETIME	Last modification time of a row.

Examples

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gaussdb=# ALTER DATABASE set ilm = on;
gaussdb=# CREATE Schema HEAT_MAP_DATA;
gaussdb=# SET current_schema=HEAT_MAP_DATA;

gaussdb=# CREATE TABLESPACE example1 RELATIVE LOCATION 'tablespace1';
gaussdb=# CREATE TABLE HEAT_MAP_DATA.heat_map_table(id INT, value TEXT) TABLESPACE example1;
gaussdb=# INSERT INTO HEAT_MAP_DATA.heat_map_table VALUES (1, 'test_data_row_1');

gaussdb=# SELECT * from DBE_HEAT_MAP.ROW_HEAT_MAP(
    owner         =>  'heat_map_data',
    segment_name  =>  'heat_map_table',
    partition_name  => NULL,
    ctid          =>  '(0,1)');
     owner     |  segment_name  | partition_name | tablespace_name | file_id | relative_fno | ctid  | writetime 
---------------+----------------+----------------+-----------------+---------+--------------+-------+-----------
 heat_map_data | heat_map_table |                | example1        |   17291 |        17291 | (0,1) | 
(1 row)