How to store XML in a database using the least amount of storage?

How to store XML in a database using the least amount of storage?

What is the best way to store a normal (ASCII) XML file into the database with minimal database size?

Storing XML files in the database with minimal storage capacity.

How to store files in a database using the least amount of storage?

Files can be stored in the database using LOB fields.
 

Use CREATE X-DOCUMENT or COPY-LOB FROM FILE to copy XML into the database field. 

The following code shows both options (choose one):

DEFINE VARIABLE MyLongCharVariable AS LONGCHAR NO-UNDO. 
DEFINE VARIABLE hXDoc AS HANDLE NO-UNDO. 

DEFINE TEMP-TABLE ttTemp NO-UNDO 
       FIELD MyClobField AS CLOB.

CREATE ttTemp. 

/* From X-DOCUMENT to LONGCHAR to CLOB */
CREATE X-DOCUMENT hXDoc.
hXDoc:LOAD("FILE", "example.xml", FALSE).
hXDoc:SAVE("LONGCHAR", MyLongCharVariable).
COPY-LOB MyLongCharVariable TO ttTemp.MyClobField.

/* From file to CLOB */
COPY-LOB FROM FILE "example.xml" TO ttTemp.MyClobField.

To further reduce space, the file could also be compressed/zipped before being stored in the database.
Progress does not provide any built-in methods to zip files but third-party libraries are available for this.

References to other documentation:

Progress article(s):
 Best practices with BLOB/CLOB fields
 How to report of the space used by LOBS?