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.
API |
Description |
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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. |
- 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) |
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