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71 lines
2.4 KiB
SQL
71 lines
2.4 KiB
SQL
/**
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* Based on https://github.com/postgres/postgres/blob/master/src/test/regress/sql/with.sql, license:
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*
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* PostgreSQL Database Management System
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* (formerly known as Postgres, then as Postgres95)
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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*
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* Portions Copyright (c) 1994, The Regents of the University of California
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose, without fee, and without a written agreement
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* is hereby granted, provided that the above copyright notice and this
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* paragraph and the following two paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
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*PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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--
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-- Tests for common table expressions (WITH query, ... SELECT ...)
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--
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-- { echoOn }
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SET allow_experimental_analyzer = 1;
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--
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-- test cycle detection
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--
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DROP TABLE IF EXISTS graph;
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CREATE TABLE graph(
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f UInt64,
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t UInt64,
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label String
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)
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ENGINE = TinyLog;
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INSERT INTO graph VALUES (1, 2, 'arc 1 -> 2'), (1, 3, 'arc 1 -> 3'), (2, 3, 'arc 2 -> 3'), (1, 4, 'arc 1 -> 4'), (4, 5, 'arc 4 -> 5'), (5, 1, 'arc 5 -> 1');
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WITH RECURSIVE search_graph AS (
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SELECT *, false AS is_cycle, [tuple(g.f, g.t)] AS path FROM graph g
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UNION ALL
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SELECT g.*, has(path, tuple(g.f, g.t)), arrayConcat(sg.path, [tuple(g.f, g.t)])
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FROM graph g, search_graph sg
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WHERE g.f = sg.t AND NOT is_cycle
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)
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SELECT * FROM search_graph;
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-- ordering by the path column has same effect as SEARCH DEPTH FIRST
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WITH RECURSIVE search_graph AS (
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SELECT *, false AS is_cycle, [tuple(g.f, g.t)] AS path FROM graph g
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UNION ALL
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SELECT g.*, has(path, tuple(g.f, g.t)), arrayConcat(sg.path, [tuple(g.f, g.t)])
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FROM graph g, search_graph sg
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WHERE g.f = sg.t AND NOT is_cycle
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)
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SELECT * FROM search_graph ORDER BY path;
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-- { echoOff }
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