ALL_TAB_COLUMNS

ALL_TAB_COLUMNS describes the columns of the tables, views, and clusters accessible to the current user. To gather statistics for this view, use the DBMS_STATS package.

Related Views

  • DBA_TAB_COLUMNS describes the columns of all tables, views, and clusters in the database.

  • USER_TAB_COLUMNS describes the columns of the tables, views, and clusters 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 table, view, or cluster
TABLE_NAME VARCHAR2(30) NOT NULL Name of the table, view, or cluster
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. The constraint should be in an ENABLE VALIDATE state.
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 columnFoot 1 
LOW_VALUE RAW(32)   Low value in the columnFootref 1
HIGH_VALUE RAW(32)   High value in the columnFootref 1
DENSITY NUMBER   If a histogram is available on COLUMN_NAME, then this column displays the selectivity of a value that spans fewer than 2 endpoints in the histogram. It does not represent the selectivity of values that span 2 or more endpoints.

If a histogram is not available on COLUMN_NAME, then the value of this column is 1/NUM_DISTINCT.Footref 1
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

  • NVARCHAR2
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)
HISTOGRAM VARCHAR2(15)   Indicates existence/type of histogram:

  • NONE

  • FREQUENCY

  • HEIGHT BALANCED

Footnote 1 These columns remain for backward compatibility with Oracle7. This information is now in the {TAB|PART}_COL_STATISTICS views.