if (topTableFilter.getCurrentSearchRowLength() < len)
len = topTableFilter.getCurrentSearchRowLength();
for (int i = 0; i < len; i++) {
if (groupByExpression == null || !groupByExpression[i]) {
Expression expr = expressions.get(i);
expr.mergeAggregate(session, topTableFilter.getValue(i));
}
}
if (sampleSize > 0 && rowNumber >= sampleSize) {
break;
}