# 10. API: LOB Objects

See Using CLOB and BLOB Data for more information about using LOBs.

Note

This object is an extension the DB API. It is returned whenever Oracle `CLOB`, `BLOB` and `BFILE` columns are fetched.

## 10.1. LOB Methods

LOB.close()

  Closes the LOB. Call this when writing is completed so that the indexes associated with the LOB can be updated – but only if `open()` was called first.

LOB.fileexists()

  Returns a boolean indicating if the file referenced by the BFILE type LOB exists.

LOB.getchunksize()

  Returns the chunk size for the internal LOB. Reading and writing to the LOB in chunks of multiples of this size will improve performance.

LOB.getfilename()

  Returns a two-tuple consisting of the directory alias and file name for a BFILE type LOB.

LOB.isopen()

  Returns a boolean indicating if the LOB has been opened using the method `open()`.

LOB.open()

  Opens the LOB for writing. This will improve performance when writing to a LOB in chunks and there are functional or extensible indexes associated with the LOB. If this method is not called, each write will perform an open internally followed by a close after the write has been completed.

LOB.read([offset=1[, amount]])

  Returns a portion (or all) of the data in the LOB object. Note that the amount and offset are in bytes for BLOB and BFILE type LOBs and in UCS-2 code points for CLOB and NCLOB type LOBs. UCS-2 code points are equivalent to characters for all but supplemental characters. If supplemental characters are in the LOB, the offset and amount will have to be chosen carefully to avoid splitting a character.

LOB.setfilename(dirAlias, name)

  Sets the directory alias and name of the BFILE type LOB.

LOB.size()

  Returns the size of the data in the LOB object. For BLOB and BFILE type LOBs, this is the number of bytes. For CLOB and NCLOB type LOBs, this is the number of UCS-2 code points. UCS-2 code points are equivalent to characters for all but supplemental characters.

LOB.trim(new_size=0)

  Trims the LOB to the new size.

LOB.write(data, offset=1)

  Writes the data to the LOB object at the given offset. The offset is in bytes for BLOB type LOBs and in UCS-2 code points for CLOB and NCLOB type LOBs. UCS-2 code points are equivalent to characters for all but supplemental characters. If supplemental characters are in the LOB, the offset will have to be chosen carefully to avoid splitting a character. Note that if you want to make the LOB value smaller, you must use the `trim()` function.

## 10.2. LOB Attributes

LOB.type

  This read-only attribute returns the type of the LOB as one of the database type constants.