Datatype Limits

Datatypes	Limit	Comments
`BFILE`	Maximum size: 4 GB Maximum size of a file name: 255 characters Maximum size of a directory name: 30 characters Maximum number of open BFILEs: see Comments	The maximum number of `BFILEs` is limited by the value of the `SESSION_MAX_OPEN_FILES` initialization parameter, which is itself limited by the maximum number of open files the operating system will allow.
`BLOB`	Maximum size: (4 GB - 1) * `DB_BLOCK_SIZE` initialization parameter (8 TB to 128 TB)	The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000^Foot 1).
`CHAR`	Maximum size: 2000 bytes	None
`CHAR VARYING`	Maximum size: 4000 bytes	None
`CLOB`	Maximum size: (4 GB - 1) * `DB_BLOCK_SIZE` initialization parameter (8 TB to 128 TB)	The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000^Footref 1).
Literals (characters or numbers in SQL or PL/SQL)	Maximum size: 4000 characters	None
`LONG`	Maximum size: 2 GB - 1	Only one `LONG` column is allowed per table.
`NCHAR`	Maximum size: 2000 bytes	None
`NCHAR VARYING`	Maximum size: 4000 bytes	None
`NCLOB`	Maximum size: (4 GB - 1) * `DB_BLOCK_SIZE` initialization parameter (8 TB to 128 TB)	The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000^Footref 1).
`NUMBER`	999...(38 9's) x10¹²⁵ maximum value -999...(38 9's) x10¹²⁵ minimum value	Can be represented to full 38-digit precision (the mantissa) Can be represented to full 38-digit precision (the mantissa)
Precision	38 significant digits	None
`RAW`	Maximum size: 2000 bytes	None
`VARCHAR`	Maximum size: 4000 bytes	None
`VARCHAR2`	Maximum size: 4000 bytes	None

^Footnote 1The absolute maximum number of columns in a table is 1000. However, when you create an object table (or a relational table with columns of object, nested table, varray, or REF type), Oracle maps the columns of the user-defined types to relational columns, creating in effect hidden columns that count toward the 1000-column limit. For details on how Oracle calculates the total number of columns in such a table, refer to Oracle Database Administrator's Guide.