ltree

问题 Materialized Path is a method for representing hierarchy in SQL. Each node contains the path itself and all its ancestors ( grandparent/parent/self ). The django-treebeard implementation of MP (docs): Each step of the path is a fixed length for consistent performance. Each node contains depth and numchild fields (fast reads at minimal cost to writes). The path field is indexed (with a standard b-tree index): The materialized path approach makes heavy use of LIKE in your database, with clauses

问题 I am using PostgreSQL and have a table with a path column that is of type ltree . The problem I am trying to solve is: given the whole tree structure, what parent has the most children excluding the root. Sample data looks like this: path column = ; has a depth of 0 and has 11 children its id is 1824 # dont want this one because its the root path column = ; has a depth of 0 and has 1 children its id is 1823 path column = 1823; has a depth of 1 and has 1 children its id is 1825 path column =

问题 Does anyone know what Java type maps to a Postgres ltree type? I create a table like so: CREATE TABLE foo (text name, path ltree); A couple of inserts: INSERT INTO foo (name, path) VALUES ( 'Alice', 'ROOT.first.parent'); INSERT INTO foo (name, path) VALUES ( 'Bob', 'ROOT.second.parent'); INSERT INTO foo (name, path) VALUES ( 'Ted', 'ROOT.first.parent.child'); INSERT INTO foo (name, path) VALUES ( 'Carol', 'ROOT.second.parent.child'); Nothing strange there. Now I want to batch this up using a

问题 I am trying to map postgresql ltree column in hibernate as follows: In entity : private String path; @Column(name="org_path", columnDefinition="ltree") public String getPath() { return path; Table structure: CREATE TABLE relationship ( relationship_id int4 NOT NULL, parent_organization_id uuid NOT NULL, child_organization_id uuid NOT NULL, org_path ltree NOT NULL, CONSTRAINT relationship_pk PRIMARY KEY (relationship_id), CONSTRAINT organization_fk3 FOREIGN KEY (parent_organization_id)