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cache_streamed_mutation: Special-case population for singular ranges

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This is an optimization which avoids creating dummy entries around row
entry when populating a singular range.
This commit is contained in:
Tomasz Grabiec
2017-10-16 11:01:24 +02:00
parent 90796893ee
commit 328faf695e
1 changed files with 20 additions and 2 deletions
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22
cache_streamed_mutation.hh
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@@ -293,7 +293,21 @@ future<> cache_streamed_mutation::read_from_underlying() {
} else if (can_populate()) {
rows_entry::compare less(*_schema);
auto& rows = _snp->version()->partition().clustered_rows();
if (!_ck_ranges_curr->start() || _last_row.refresh(*_snp)) {
if (query::is_single_row(*_schema, *_ck_ranges_curr)) {
with_allocator(_snp->region().allocator(), [&] {
auto e = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(_ck_ranges_curr->start()->value()));
// Use _next_row iterator only as a hint, because there could be insertions after _upper_bound.
auto insert_result = rows.insert_check(_next_row.get_iterator_in_latest_version(), *e, less);
auto inserted = insert_result.second;
auto it = insert_result.first;
if (inserted) {
e.release();
auto next = std::next(it);
it->set_continuous(next->continuous());
}
});
} else if (!_ck_ranges_curr->start() || _last_row.refresh(*_snp)) {
with_allocator(_snp->region().allocator(), [&] {
auto e = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(*_schema, _upper_bound, is_dummy::yes, is_continuous::yes));
@@ -441,7 +455,11 @@ void cache_streamed_mutation::move_to_current_range() {
auto adjacent = _next_row.advance_to(_lower_bound);
_next_row_in_range = !after_current_range(_next_row.position());
if (!adjacent && !_next_row.continuous()) {
if (_ck_ranges_curr->start()) {
// FIXME: We don't insert a dummy for singular range to avoid allocating 3 entries
// for a hit (before, at and after). If we supported the concept of an incomplete row,
// we could insert such a row for the lower bound if it's full instead, for both singular and
// non-singular ranges.
if (_ck_ranges_curr->start() && !query::is_single_row(*_schema, *_ck_ranges_curr)) {
// Insert dummy for lower bound
if (can_populate()) {
// FIXME: _lower_bound could be adjacent to the previous row, in which case we could skip this