/**
* @return the unused section of the page, or null if fully applied. pagesIndex guaranteed to have
* at least one row after this method returns
*/
private Page updatePagesIndex(Page page) {
checkArgument(page.getPositionCount() > 0);
// TODO: Fix pagesHashStrategy to allow specifying channels for comparison, it currently
// requires us to rearrange the right side blocks in consecutive channel order
Page preGroupedPage = rearrangePage(page, preGroupedChannels);
if (pagesIndex.getPositionCount() == 0
|| pagesIndex.positionEqualsRow(
preGroupedPartitionHashStrategy, 0, 0, preGroupedPage.getBlocks())) {
// Find the position where the pre-grouped columns change
int groupEnd = findGroupEnd(preGroupedPage, preGroupedPartitionHashStrategy, 0);
// Add the section of the page that contains values for the current group
pagesIndex.addPage(page.getRegion(0, groupEnd));
if (page.getPositionCount() - groupEnd > 0) {
// Save the remaining page, which may contain multiple partitions
return page.getRegion(groupEnd, page.getPositionCount() - groupEnd);
} else {
// Page fully consumed
return null;
}
} else {
// We had previous results buffered, but the new page starts with new group values
return page;
}
}
