b-tree

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . I am doing a project in which I require btree or b+tree data structure. Does anyone know of an existing implementation of btree or b+tree (with insert, delete, search algorithms)? It should accept string as input and form btree or b+tree of these string. 回答1: In the lack of details about the problem that you

问题 I am trying to implement a database index based on the data structure (B link tree) and algorithms suggested by Lehman and Yao in this paper. In page 2, the authors state that: The disk is partitioned in sections of fixed size (physical pages; in this paper, these correspond to the nodes of the tree). These are the only units that can be read or written by a process. [emphasis mine] (...) (...) a process is allowed to lock and unlock a disk page. This lock gives that process exclusive

问题 I'm looking for a tool to get a decent estimate of how large a MongoDB index will be based on a few signals like: How many documents in my collection The size of the indexed field(s) The size of the _id I'm using if not ObjectId Geo/Non-geo Has anyone stumbled across something like this? I can imagine it would be extremely useful given Mongo's performance degradation once it hits the memory wall and documents start getting paged out to disk. If I have a functioning database and want to add

问题 I'm trying to learn about b-tree and every source I can find seem to omits the discussion about how to remove an element from the tree while preserving the b-tree properties. Can someone explain the algorithm or point me to resource that do explain how it's done? 回答1: There's an explanation of it on the Wikipedia page. B-tree - Deletion 回答2: If you haven't got it yet, I strongly recommend Carmen & al Introduction to Algorithms 3rd Edition . It is not described because the operations naturally

问题 Am I missing something, or is there no way to get an iterator beginning at the newly-inserted value in a BTreeSet ? BTreeSet::insert just returns a boolean. For comparison, the insert method for std::map in C++ returns a pair of an iterator and a boolean. It is possible to look up the newly-inserted element and get the iterator that way, but that's inefficient. This isn't a duplicate of How to lookup from and insert into a HashMap efficiently? as I need to get an iterator pointing to the

问题 T-tree algorithm is described in this paper And T*-Tree is an improvement from T-tree for better use of query operations, including range queries and which contains all other good features of T-tree. This algorithm is described in this paper "T*-tree: A Main Memory Database Index Structure for Real-Time Applications". According to this research paper, T-Tree is faster than B-tree/B+tree when datasets fit in the memory. I implemented T-Tree/T*Tree as they described in these papers and compared

问题 I have a question, related to DB theory: Let's assume that we have table with 3 columns: [PersonID], [PersonName], [PersonAge] . We know that when we have a nonclustered index by one column, SQL Server orders table data in accordance with specified column and build B+ tree from it. And when we need to find the row using such an index, SQL Server scans the B++ tree by comparing one atomic data object ( int or string , for example). That is clear, how non-clustered index works and find data

问题 If we put the select performance aside, which one is faster when it comes to insert. I couldn't find any thorough explanation for this. Can someone please explain? This question just labels bitmaps as inefficient but I want to know why. Thanks, 回答1: Bitmap indexes can be problematic for inserts if there is contention. If you have a single thread doing the inserts they are fine, but if there are multiple threads doing inserts and perhaps updates and deletes they tend to limit performance due

问题 This online book describes how MySQL leverages B-Trees for indexing data. Time complexity depends on the number of entries per node. How many entries does MySQL hold in one node? 回答1: Rule of Thumb: 100. This applies to InnoDB data BTrees and Index BTrees. However, it can be quite far off. One extreme: only 1 data record in a node -- due to large row size and/or activity such as DELETEs . Another case: A table with 1 record will still occupy a full 16KB block. Other extreme: 500 index records

问题 I'm trying to print a b tree in level order,but it keeps on crashing. Im not sure whats the real reason but i think its crashing because of the pointers. Im trying to use a function i found online that goes through each level and puts it in a queue and prints it, but ive run into this problem.If anyone has another way of doing it please let me know. // C++ program for B-Tree insertion #include<iostream> #include <queue> using namespace std; int ComparisonCount = 0; // A BTree node class