public RecordIterator indexIteratorAfter(int columnIndex, Field startValue) throws IOException {
		synchronized (db) {
			IndexTable indexTable = secondaryIndexes.get(columnIndex);
			if (indexTable == null) {
				throw new IOException("Index required (" + getName() + "," + columnIndex + ")");
			}
			return new KeyToRecordIterator(this, indexTable.keyIteratorAfter(startValue));
		}
	}
Iterate over the records using a secondary index.  Sorting occurs on the
specified schema column.  The iterator's initial position immediately follows 
the specified startValue. If this value does not exist, the initial position corresponds
to where it would exist.
This table must have been constructed with a secondary index on the specified column.
@param columnIndex schema column to sort on.
@param startValue the starting value of the secondary index field.
@return RecordIterator record iterator.
@throws IOException if a secondary index does not exist for the specified
column, or the wrong field type was specified, or an I/O error occurs.
Ghidra/Framework/DB/src/main/java/db/Table.java