Questions tagged [tree]

Trees are special cases of graphs. They are acyclic i.e. there is at most one path from any node to any other node. Typical uses include hierarchical data (parent-child relationships; roll-up aggregate values) and BTree indexes.

11 questions with no upvoted or accepted answers
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Working on a decision tree database design

I'm doing the conceptual model for a Decision tree database. The goal is store any Decision tree. I have four entity types: DecisionTree, Node, Branch and Leaf. Each Decision tree is composed of ...
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Drop intermediate results of recursive query in Postgres

I'm trying to aggregate the contents of a column from a directed acyclic graph (DAG) stored in a Postgres table. Each dag row has an id, bytes, and may also have a parent referencing another row. I'm ...
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Retrieve all product from one category (tree model)

I'm using MySQL, have categories in a tree model. One product belongs to only one (leaf) category. What I want to accomplish is, given one category (any, could or not be a leaf or a root), return ...
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222 views

Building a tree in Apache Derby 10.10

I know this question has been asked probably a million times, so please forgive me asking it again. I am not a DBA and have very little knowledge of SQL and Derby, but need some kind of a solution as ...
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0answers
67 views

Scalable way to manage aggregated statistics over time in hierarchy?

I'm using a closure table (Postgres through Django) to roll up stats through a hierarchical tree. When a node that is 10 layers deep has a value that increases, each parent's sum total of that value ...
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55 views

Nested set model in higher dimensions

The nested set structure is well-known and involves using left and right values to denote the relative heirarchy of nodes on one axis. Is there a generalization of this structure to higher dimensions?...
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1answer
35 views

Mongodb tree structure questions and answers

I'm looking to build a question answer survey system where some questions will be based on the answer of the parent question. The hierarchy level of the questions can go any number of depth based on ...
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0answers
33 views

How to UPSERT tree in PostgreSQL?

There is a tree-structures in two-tables with ParentId field. How to make UPSERT (INSERT ... ON CONFLICT (...) DO UPDATE ...) between them? The problem is that parent record for the current record in ...
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1answer
45 views

Optimizing one-way syncing of large (wide) tree

I deal with several trees that can vary in size (they all have depths of ~8-10) but it's not unusual for them to consist of ~50-100k nodes. At the moment, the trees are stored using simple parent_id ...
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57 views

How does query parameters work under the hood?

I thought about how can it work under the hood and I came with an idea Db engine receives query with parameters and also defined values of those parameters SQL is being parsed into syntax tree like ...
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1answer
818 views

MySql - Get all child categories until not exists

Based on this answer, can you please tell me what's wrong in the next code ? I'm trying to get all child categories. The example that I try it is: DELIMITER $$ DROP FUNCTION IF EXISTS `...