Monday, July 13, 2009

DBA_NESTED_TABLE_COLS

DBA_NESTED_TABLE_COLS describes the columns of all nested tables in the database. To gather statistics for this view, use the SQL ANALYZE statement.

Related Views

  • ALL_NESTED_TABLE_COLS describes the columns of the nested tables accessible to the current user. To gather statistics for this view, use the ANALYZE SQL statement or the DBMS_STATS package.
  • USER_NESTED_TABLE_COLS describes the columns of the nested tables owned by the current user. This view does not display the OWNER column.

Column

Datatype

NULL

Description

OWNER

VARCHAR2(30)

NOT NULL

Owner of the nested table

TABLE_NAME

VARCHAR2(30)

NOT NULL

Name of the nested table

COLUMN_NAME

VARCHAR2(30)

NOT NULL

Column name

DATA_TYPE

VARCHAR2(106)

Datatype of the column

DATA_TYPE_MOD

VARCHAR2(3)

Datatype modifier of the column

DATA_TYPE_OWNER

VARCHAR2(30)

Owner of the datatype of the column

DATA_LENGTH

NUMBER

NOT NULL

Length of the column (in bytes)

DATA_PRECISION

NUMBER

Decimal precision for NUMBER datatype; binary precision for FLOAT datatype; NULL for all other datatypes

DATA_SCALE

NUMBER

Digits to the right of the decimal point in a number

NULLABLE

VARCHAR2(1)

Indicates whether a column allows NULLs. The value is N if there is a NOT NULL constraint on the column or if the column is part of a PRIMARY KEY.

COLUMN_ID

NUMBER

Sequence number of the column as created

DEFAULT_LENGTH

NUMBER

Length of the default value for the column

DATA_DEFAULT

LONG

Default value for the column

NUM_DISTINCT

NUMBER

Number of distinct values in the column (The column remains for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views.)

LOW_VALUE

RAW(32)

Low value in the column (The column remains for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views.)

HIGH_VALUE

RAW(32)

High value in the column (The column remains for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views.)

DENSITY

NUMBER

Density of the column (The column remains for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views.)

NUM_NULLS

NUMBER

Number of NULLs in the column

NUM_BUCKETS

NUMBER

Number of buckets in the histogram for the column

Note: The number of buckets in a histogram is specified in the SIZE parameter of the ANALYZE SQL statement. However, Oracle Database does not create a histogram with more buckets than the number of rows in the sample. Also, if the sample contains any values that are very repetitious, Oracle Database creates the specified number of buckets, but the value indicated by this column may be smaller because of an internal compression algorithm.

LAST_ANALYZED

DATE

Date on which this column was most recently analyzed

SAMPLE_SIZE

NUMBER

Sample size used in analyzing this column

CHARACTER_SET_NAME

VARCHAR2(44)

Name of the character set:

  • CHAR_CS
  • NCHAR_CS

CHAR_COL_DECL_LENGTH

NUMBER

Declaration length of the character type column

GLOBAL_STATS

VARCHAR2(3)

For partitioned tables, indicates whether column statistics were collected for the table as a whole (YES) or were estimated from statistics on underlying partitions and subpartitions (NO)

USER_STATS

VARCHAR2(3)

Indicates whether statistics were entered directly by the user (YES) or not (NO)

AVG_COL_LEN

NUMBER

Average length of the column (in bytes)

CHAR_LENGTH

NUMBER

Displays the length of the column in characters. This value only applies to the following datatypes:

  • CHAR
  • VARCHAR2
  • NCHAR
  • NVARCHAR

CHAR_USED

VARCHAR2(1)

Indicates that the column uses BYTE length semantics (B) or CHAR length semantics (C), or whether the datatype is not any of the following (NULL):

  • CHAR
  • VARCHAR2
  • NCHAR
  • NVARCHAR2

V80_FMT_IMAGE

VARCHAR2(3)

Indicates whether the column data is in release 8.0 image format (YES) or not (NO)

DATA_UPGRADED

VARCHAR2(3)

Indicates whether the column data has been upgraded to the latest type version format (YES) or not (NO)

HIDDEN_COLUMN

VARCHAR2(3)

Indicates whether the column is a hidden column (YES) or not (NO)

VIRTUAL_COLUMN

VARCHAR2(3)

Indicates whether the column is a virtual column (YES) or not (NO)

SEGMENT_COLUMN_ID

NUMBER

Sequence number of the column in the segment

INTERNAL_COLUMN_ID

NUMBER

NOT NULL

Internal sequence number of the column

HISTOGRAM

VARCHAR2(15)

Indicates existence/type of histogram:

  • NONE
  • FREQUENCY
  • HEIGHT BALANCED

QUALIFIED_COL_NAME

VARCHAR2(4000)

Qualified column name

Oracle data dictionary views

Oracle dynamic performance views

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