DBE_COMPRESSION

Interface 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 interface supports only DNs in the distributed database.

• DBE_COMPRESSION.GET_COMPRESSION_RATIO

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

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  DBE_COMPRESSION.GET_COMPRESSION_RATIO ( scratchtbsname IN TEXT, ownname IN TEXT, objname IN TEXT, subobjname IN TEXT, comptype IN INTEGER, 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 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 pages occupied by sampled rows after compression.
  blkcnt_uncmp	Number of pages occupied by sampled rows before compression.
  row_cmp	Number of compressed rows on a single page.
  row_uncmp	Number of uncompressed rows on a single page.
  cmp_ratio	Compression ratio.
  comptype_str	Character string of the compression type.
  sample_ratio	Sampling rate.
  objtype	Object type. The options are as follows: 1: table object.

• DBE_COMPRESSION.GET_COMPRESSION_TYPE

  This interface is used to obtain the compression type of a specified row based on input parameters. This interface is an O&M interface and does not check the visibility. That is, if the input CTID is a deleted row, this interface 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 TEXT, tablename IN TEXT, ctid IN INTEGER, subobjname IN TEXT DEFAULT NULL, comptype OUT INTEGER);

  Table 3 DBE_COMPRESSION.GET_COMPRESSION_TYPE parameters

  Parameter	Description
  ownname	Data object owner (schema to which the data object belongs).
  tablename	Data object name.
  ctid	CTID of the target row.
  subobjname	Name of a data subobject.
  comptype	Compression type. The options are as follows: 1: uncompressed. 2: advanced compression.