Displaying the layout of LOB columns

 

When you use CL commands, such as Display Physical File Member (DSPPFM), to display a row of data from a table that holds large object (LOB) columns, the LOB data stored in the row is not displayed. Instead, the database shows a special value for the LOB columns.

The layout of this special value is as follows:

• 13 to 28 bytes of hexadecimal zeros.

• 16 bytes beginning with *POINTER and followed by blanks.

The number of bytes in the first portion of the value is set to the number needed to 16 byte boundary align the second part of the value.

For example, say you have a table that holds three columns: ColumnOne Char(10), ColumnTwo CLOB(40K), and ColumnThree BLOB(10M). If you were to issue a DSPPFM of this table, each row of data looks as follows.

• For ColumnOne: 10 bytes filled with character data.

• For ColumnTwo: 22 bytes filled with hexadecimal zeros and 16 bytes filled with '*POINTER '.

• For ColumnThree: 16 bytes filled with hexadecimal zeros and 16 bytes filled with '*POINTER '.

The full set of commands that display LOB columns in this way is:

• Display Physical File Member (DSPPFM)

• Copy File (CPYF) when the value *PRINT is specified for the TOFILE keyword

• Display Journal (DSPJRN)

• Retrieve Journal Entry (RTVJRNE)

• Receive Journal Entry (RCVJRNE) when the values *TYPE1, *TYPE2, *TYPE3 and *TYPE4 are specified for the ENTFMT keyword.

 

Parent topic:

Large objects