public SliceQueryFilter withUpdatedStart(Composite newStart, CFMetaData cfm) {
Comparator<Composite> cmp = reversed ? cfm.comparator.reverseComparator() : cfm.comparator;
// Check our slices to see if any fall before the new start (in which case they can be removed)
// or
// if they contain the new start (in which case they should start from the page start).
// However, if the
// slices would include static columns, we need to ensure they are also fetched, and so a
// separate
// slice for the static columns may be required.
// Note that if the query is reversed, we can't handle statics by simply adding a separate slice
// here, so
// the reversed case is handled by SliceFromReadCommand instead. See CASSANDRA-8502 for more
// details.
List<ColumnSlice> newSlices = new ArrayList<>();
boolean pastNewStart = false;
for (ColumnSlice slice : slices) {
if (pastNewStart) {
newSlices.add(slice);
continue;
}
if (slice.isBefore(cmp, newStart)) {
if (!reversed && sliceIncludesStatics(slice, cfm))
newSlices.add(new ColumnSlice(Composites.EMPTY, cfm.comparator.staticPrefix().end()));
continue;
} else if (slice.includes(cmp, newStart)) {
if (!reversed && sliceIncludesStatics(slice, cfm) && !newStart.isEmpty())
newSlices.add(new ColumnSlice(Composites.EMPTY, cfm.comparator.staticPrefix().end()));
newSlices.add(new ColumnSlice(newStart, slice.finish));
} else {
newSlices.add(slice);
}
pastNewStart = true;
}
return withUpdatedSlices(newSlices.toArray(new ColumnSlice[newSlices.size()]));
}
public boolean maySelectPrefix(CType type, Composite prefix) {
for (ColumnSlice slice : slices) if (slice.includes(type, prefix)) return true;
return false;
}
/** Returns true if the slice includes static columns, false otherwise. */
private boolean sliceIncludesStatics(ColumnSlice slice, CFMetaData cfm) {
return cfm.hasStaticColumns()
&& slice.includes(
reversed ? cfm.comparator.reverseComparator() : cfm.comparator,
cfm.comparator.staticPrefix().end());
}