21. The machine-readable storage medium of claim 20 , further comprising instructions which, when executed by one or more processors, causes: receiving a new XML document to store in said collection of XML documents; extracting a new set of values from the new XML document, wherein each value in said set of new values corresponds to a different element contained in said collection of XML documents; populating each column of said plurality of columns from said tables with the new set of values extracted from the new XML document.
31. The machine-readable storage medium of claim 21 , wherein a column from said plurality of columns maps to two or more elements.