Pivot Table.

i am facing a problem on creating a pivot table using
externa data source(i.e. Oracle SQL database) The amount
of data exceeds 70,000 entries.when i create a pivot
table, an error message pops up:
"A field in your source data has more unique items than
can be used in a PivotTable. Microsoft Excel may not be
able to create the PivotTable, or may crate the PivotTable
without the data from this field."
My question is, how can i create a pivot table with this
huge database? is it got limitation of the amount of data
entry that can be used to create pivot table? if yes, how
to solve this problem?
thank you.