DBE_COMPRESSION

API Description

Evaluates the sampling compression rate of a specified data object or obtains the compression type of a specified row of data based on the input parameters.

The GET_COMPRESSION_TYPE API supports only DNs in the distributed database.

• DBE_COMPRESSION.GET_COMPRESSION_RATIO

  Evaluates the sampling compression rate of a specified data object based on input parameters. The prototype is as follows:

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  DBE_COMPRESSION.GET_COMPRESSION_RATIO( SCRATCHTBSNAME IN VARCHAR2, OWNNAME IN VARCHAR2, OBJNAME IN VARCHAR2, SUBOBJNAME IN VARCHAR2, COMPTYPE IN NUMBER, BLKCNT_CMP OUT INTEGER, BLKCNT_UNCMP OUT INTEGER, ROW_CMP OUT INTEGER, ROW_UNCMP OUT INTEGER, CMP_RATIO OUT NUMBER, COMPTYPE_STR OUT VARCHAR2, SAMPLE_RATIO IN NUMBER DEFAULT 20, OBJTYPE IN INTEGER DEFAULT 1);

  Table 2 DBE_COMPRESSION.GET_COMPRESSION_RATIO API parameters

  Parameter	Description
  SCRATCHTBSNAME	Tablespace to which a data object belongs.
  OWNNAME	Data object owner (schema to which the data object belongs).
  OBJNAME	Data object name.
  SUBOBJNAME	Name of a data subobject.
  COMPTYPE	Compression type. The options are as follows: 1: uncompressed. 2: advanced compression.
  BLKCNT_CMP	Number of blocks occupied by compressed samples.
  BLKCNT_UNCMP	Number of blocks occupied by uncompressed samples.
  ROW_CMP	Number of rows that can be contained in a single block after samples are compressed.
  ROW_UNCMP	Number of rows that can be contained in a single block when samples are not compressed.
  CMP_RATIO	Compression ratio, that is, blkcnt_uncmp divided by blkcnt_cmp.
  COMPTYPE_STR	Character string that describes the compression type.
  SAMPLE_RATIO	Sampling ratio. The value is an integer or floating-point number ranging from 0 to 100, corresponding to the sampling ratio of N percent. The default value is 20, indicating that 20% of the rows are sampled.
  OBJTYPE	Object type. The options are as follows: 1: table object.

• DBE_COMPRESSION.GET_COMPRESSION_TYPE

  This API is used to obtain the compression type of a specified row based on input parameters. This API is an O&M API and does not check the visibility. That is, if the input CTID is a deleted row, this API still returns the latest status of the current row on the page. The prototype is as follows:

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  DBE_COMPRESSION.GET_COMPRESSION_TYPE( OWNNAME IN VARCHAR2, TABNAME IN VARCHAR2, CTID IN TEXT, SUBOBJNAME IN VARCHAR2 DEFAULT NULL, BUCKETID IN pg_catalog.int2 DEFAULT NULL)

  Table 3 DBE_COMPRESSION.GET_COMPRESSION_TYPE API parameters

  Parameter	Description
  OWNNAME	Data object owner (schema to which the data object belongs).
  TABNAME	Data object name.
  CTID	CTID of the target row.
  SUBOBJNAME	Name of a data subobject.
  BUCKETID	Table bucket ID of the target row, which is used only for bucket tables. The default value is NULL.