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Questions tagged [b-tree-index]

57 questions
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What is Minimum Occupancy in B-Trees?

I'm fairly new to the B-Tree concept, I'm currently reading slides for a course that can be found here: http://www-db.deis.unibo.it/courses/TBD/Lezioni/02%20-%20Indices.pdf I read that B-trees have a "minimum occupancy" of 50%. What does that mean?…
mmarc
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postgresql doesn't use index for primary key = foreign key

I have 3 main tables, ts_entity(id,short_name,name,type_id) ts_entry_entity(id,entity_id,entry_id) ts_entry(id, ... other columns ...) All the id columns are UUID, and have a Btree index. ts_entry_entity.entity_id has foreign key to ts_entity.id,…
Abner
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How does oracle indexes manage and maintain B-Tree Indexing for columns with dynamically changing data?

I am wondering how Oracle [or any other database] manages and maintains B-Tree indexing for columns with dynamically changing data. Suppose I have a table with the following columns: Now if I have indexing on (Status) [which does not make much…
dpk
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Traversing B-Tree Structure Algorithm

I'm having a hard time trying to write a traversing function that outputs a child-node's parent-nodes. Take a look at the example b-tree Here is the sample dataset I'm using: $nodes = array( array('f','b'), array('f','g'), array('b','a'), …
user7892649
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Key-value store by foldername

We have our in houses noSQL db, that basically store everything in a compact binary file. Now, I need a data structure similar to key-value store or B+Tree. The issue is 'value' in my case can be of different types, and of size very volatile, could…
ctNGUYEN
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MySQL - Using PRIMARY KEY - UNIQUE INDEX related table many to many

happy day. I am creating a database of movies, all movies will receive one vote for each user, valuing as it seemed the movie, "Good, good or fair" These votes of these stored in a table [movies_has_rating] that have the ID of the user who made the…
Learning and sharing
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Boolean column in index and filter sections of explain in postgres

I have a table with boolean column - "is_woman" bool DEFAULT true I have an btree index with this column (and some others like age, town and so on) - is_woman ASC NULLS LAST I have a query with this column - is_woman IS FALSE As a result I get an…
Anton
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Databases and B+Trees indexes

Where can I find information on whether which databases are using B+Trees over B-Trees for their index implementations? Oracle appears to be using B+Trees. Although they don't describe it on their documentation, their graphics appear to be pointing…
Pablo Santa Cruz
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GEO2D indexes for search by two ranges of date (timeseries)

I am doing a kind of room reservation system where a collection is containing documents which contains two dates : a begin date and an end date. I would like to be able to find all the reservation which begin date is between two dates and end date…
scoulomb
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Cost of JOIN with indices

Given the following: blocksize = 4K relation students(S#, Sname, Age,....) relation taken(S#, C#, Grade) Number of student records = 10,000 Number of taken records = 50,000 Size of student records = 200 bytes Size of taken records = 50 bytes If…
Shay Zilberman
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Binary Search Tree Generation from increasing index

I have a vector of parent pointers [ 0 1 1 2 2 3 3 5 5 ....] which is basically a binary tree. The index is the child and the corresponding value represents the index of its parent in the same vector. e.g: in the above vector, if you count to index…
Wajahat
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Why in B-tree and B+_tree store from half-full to complete-full in each non-leaf node

I've just learn B-tree and B+-tree in DBMS. I don't understand why a non-leaf node in tree has between [n/2] and n children, when n is fix for particular tree. Why is that? and advantage of that? Thanks !
kju
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why at depth 2, a B+ tree of order 2 has a MAXIMUM of 5*5*4 = 100 item?

when I learned B+ tree knowledge , I saw this article, but I don't quite understand how this 100 is calculated. can anyone help explain？
bootstrap2025
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Speed up b-tree

I wrote a simple implementation of a b-tree, and the problem is that it is too slow (tl9 on codeforces). What should i change to speed up this tree? The memory limit problem can be easily fixed by increasing the constant b, but then there are time…
niripsa
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How to apply the index line "my_table_" btree () to a table?

I am managing a postgres db created by third parts. One of the tables is described as \d my_table; Table "my_table" ... Indexes: "my_table_pkey" PRIMARY KEY, btree (dt, ida, idm, idd, idt, idr) "my_table_fa" btree (dt, idd, idt, idfa,…
Tms91
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