Revision 0f0076ed5abd1540dd0b7af5d51cde529c178d52 authored by Haobo Xu on 13 June 2014, 02:03:22 UTC, committed by Haobo Xu on 19 June 2014, 01:16:07 UTC
Summary: Currently, the in-memory hash index of blockbased table uses a precise hash map to track the prefix to block range mapping. In some use cases, especially when prefix itself is big, the memory overhead becomes a problem. This diff introduces a fixed hash bucket array that does not store the prefix and allows prefix collision, which is similar to the plaintable hash index, in order to reduce the memory consumption. Just a quick draft, still testing and refining. Test Plan: unit test and shadow testing Reviewers: dhruba, kailiu, sdong Reviewed By: sdong Subscribers: leveldb Differential Revision: https://reviews.facebook.net/D19047
1 parent 3525aac
iter_heap.h
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
#pragma once
#include <queue>
#include "rocksdb/comparator.h"
#include "table/iterator_wrapper.h"
namespace rocksdb {
// Return the max of two keys.
class MaxIteratorComparator {
public:
MaxIteratorComparator(const Comparator* comparator) :
comparator_(comparator) {}
bool operator()(IteratorWrapper* a, IteratorWrapper* b) {
return comparator_->Compare(a->key(), b->key()) <= 0;
}
private:
const Comparator* comparator_;
};
// Return the max of two keys.
class MinIteratorComparator {
public:
// if maxHeap is set comparator returns the max value.
// else returns the min Value.
// Can use to create a minHeap or a maxHeap.
MinIteratorComparator(const Comparator* comparator) :
comparator_(comparator) {}
bool operator()(IteratorWrapper* a, IteratorWrapper* b) {
return comparator_->Compare(a->key(), b->key()) > 0;
}
private:
const Comparator* comparator_;
};
} // namespace rocksdb
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