Support for SingleDelete()
Summary:
This patch fixes #7460559. It introduces SingleDelete as a new database
operation. This operation can be used to delete keys that were never
overwritten (no put following another put of the same key). If an overwritten
key is single deleted the behavior is undefined. Single deletion of a
non-existent key has no effect but multiple consecutive single deletions are
not allowed (see limitations).
In contrast to the conventional Delete() operation, the deletion entry is
removed along with the value when the two are lined up in a compaction. Note:
The semantics are similar to @igor's prototype that allowed to have this
behavior on the granularity of a column family (
https://reviews.facebook.net/D42093 ). This new patch, however, is more
aggressive when it comes to removing tombstones: It removes the SingleDelete
together with the value whenever there is no snapshot between them while the
older patch only did this when the sequence number of the deletion was older
than the earliest snapshot.
Most of the complex additions are in the Compaction Iterator, all other changes
should be relatively straightforward. The patch also includes basic support for
single deletions in db_stress and db_bench.
Limitations:
- Not compatible with cuckoo hash tables
- Single deletions cannot be used in combination with merges and normal
deletions on the same key (other keys are not affected by this)
- Consecutive single deletions are currently not allowed (and older version of
this patch supported this so it could be resurrected if needed)
Test Plan: make all check
Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor
Reviewed By: igor
Subscribers: maykov, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43179
9 years ago
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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#include "db/compaction_iterator.h"
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#include "util/testharness.h"
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#include "util/testutil.h"
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namespace rocksdb {
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class CompactionIteratorTest : public testing::Test {
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public:
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CompactionIteratorTest() : cmp_(BytewiseComparator()), snapshots_({}) {}
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void InitIterator(const std::vector<std::string>& ks,
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const std::vector<std::string>& vs,
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SequenceNumber last_sequence) {
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Compaction filter on merge operands
Summary:
Since Andres' internship is over, I took over https://reviews.facebook.net/D42555 and rebased and simplified it a bit.
The behavior in this diff is a bit simpler than in D42555:
* only merge operators are passed through FilterMergeValue(). If fitler function returns true, the merge operator is ignored
* compaction filter is *not* called on: 1) results of merge operations and 2) base values that are getting merged with merge operands (the second case was also true in previous diff)
Do we also need a compaction filter to get called on merge results?
Test Plan: make && make check
Reviewers: lovro, tnovak, rven, yhchiang, sdong
Reviewed By: sdong
Subscribers: noetzli, kolmike, leveldb, dhruba, sdong
Differential Revision: https://reviews.facebook.net/D47847
9 years ago
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merge_helper_.reset(new MergeHelper(Env::Default(), cmp_, nullptr, nullptr,
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nullptr, 0U, false, 0));
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Support for SingleDelete()
Summary:
This patch fixes #7460559. It introduces SingleDelete as a new database
operation. This operation can be used to delete keys that were never
overwritten (no put following another put of the same key). If an overwritten
key is single deleted the behavior is undefined. Single deletion of a
non-existent key has no effect but multiple consecutive single deletions are
not allowed (see limitations).
In contrast to the conventional Delete() operation, the deletion entry is
removed along with the value when the two are lined up in a compaction. Note:
The semantics are similar to @igor's prototype that allowed to have this
behavior on the granularity of a column family (
https://reviews.facebook.net/D42093 ). This new patch, however, is more
aggressive when it comes to removing tombstones: It removes the SingleDelete
together with the value whenever there is no snapshot between them while the
older patch only did this when the sequence number of the deletion was older
than the earliest snapshot.
Most of the complex additions are in the Compaction Iterator, all other changes
should be relatively straightforward. The patch also includes basic support for
single deletions in db_stress and db_bench.
Limitations:
- Not compatible with cuckoo hash tables
- Single deletions cannot be used in combination with merges and normal
deletions on the same key (other keys are not affected by this)
- Consecutive single deletions are currently not allowed (and older version of
this patch supported this so it could be resurrected if needed)
Test Plan: make all check
Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor
Reviewed By: igor
Subscribers: maykov, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43179
9 years ago
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iter_.reset(new test::VectorIterator(ks, vs));
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iter_->SeekToFirst();
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c_iter_.reset(new CompactionIterator(iter_.get(), cmp_, merge_helper_.get(),
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last_sequence, &snapshots_,
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Env::Default(), false));
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}
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const Comparator* cmp_;
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std::vector<SequenceNumber> snapshots_;
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std::unique_ptr<MergeHelper> merge_helper_;
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std::unique_ptr<test::VectorIterator> iter_;
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std::unique_ptr<CompactionIterator> c_iter_;
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};
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// It is possible that the output of the compaction iterator is empty even if
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// the input is not.
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TEST_F(CompactionIteratorTest, EmptyResult) {
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InitIterator({test::KeyStr("a", 5, kTypeSingleDeletion),
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test::KeyStr("a", 3, kTypeValue)},
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{"", "val"}, 5);
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c_iter_->SeekToFirst();
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ASSERT_FALSE(c_iter_->Valid());
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}
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// If there is a corruption after a single deletion, the corrupted key should
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// be preserved.
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TEST_F(CompactionIteratorTest, CorruptionAfterSingleDeletion) {
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InitIterator({test::KeyStr("a", 5, kTypeSingleDeletion),
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test::KeyStr("a", 3, kTypeValue, true),
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test::KeyStr("b", 10, kTypeValue)},
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{"", "val", "val2"}, 10);
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c_iter_->SeekToFirst();
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ASSERT_TRUE(c_iter_->Valid());
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ASSERT_EQ(test::KeyStr("a", 5, kTypeSingleDeletion),
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c_iter_->key().ToString());
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c_iter_->Next();
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ASSERT_TRUE(c_iter_->Valid());
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ASSERT_EQ(test::KeyStr("a", 3, kTypeValue, true), c_iter_->key().ToString());
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c_iter_->Next();
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ASSERT_TRUE(c_iter_->Valid());
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ASSERT_EQ(test::KeyStr("b", 10, kTypeValue), c_iter_->key().ToString());
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c_iter_->Next();
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ASSERT_FALSE(c_iter_->Valid());
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}
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} // namespace rocksdb
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int main(int argc, char** argv) {
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::testing::InitGoogleTest(&argc, argv);
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return RUN_ALL_TESTS();
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}
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