Technology dependencies caching and integrity checks
* Added table that will contain the cached technology dependencies. * Implemented trigger functions that update the cache and make sure there are no cycles or redundancies in the technology graph. * The following SQL files need to be (re-)executed: -> 030-data/080-techs.sql (for the defs.techdep_cache table) -> 040-functions/026-technology-dependencies.sql (new file)
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legacyworlds-server-data/db-structure/parts/040-functions
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-- LegacyWorlds Beta 6
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-- PostgreSQL database scripts
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--
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-- Functions and triggers that maintain the technology
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-- dependency cache and, generally speaking, the integrity
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-- of the technology graph.
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--
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-- Copyright(C) 2004-2012, DeepClone Development
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-- --------------------------------------------------------
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/*
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* Dependency tree copy function
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* ------------------------------
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*
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* This function is used when a dependency is added. It allows a dependency
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* tree to be copied as the child of another node on a different tree.
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*
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* Parameters:
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* _reverse Whether the tree being copied is a reverse or
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* forward dependency tree
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* _src Identifier of the source tree
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* _dest Identifier of the destination tree
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* _cache Identifier of the cache entry to use as a parent
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* _depth Depth of the parent node
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* _dependency Identifier of the dependency being added
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*/
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DROP FUNCTION IF EXISTS defs.tdcache_copy_tree(
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BOOLEAN , INT , INT , INT , INT , INT ) CASCADE;
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CREATE FUNCTION defs.tdcache_copy_tree(
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_reverse BOOLEAN ,
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_src INT ,
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_dest INT ,
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_cache INT ,
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_depth INT ,
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_dependency INT )
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RETURNS VOID
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LANGUAGE PLPGSQL
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STRICT VOLATILE
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AS $tdcache_copy_tree$
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DECLARE
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_record RECORD;
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_new_entry INT;
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BEGIN
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CREATE TEMPORARY TABLE tdcache_copy_ids(
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old_id INT ,
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new_id INT
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);
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FOR _record IN
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SELECT * FROM defs.techdep_cache
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WHERE technology_name_id = _src
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AND tdcache_reverse = _reverse
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ORDER BY tdcache_depth ASC
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LOOP
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-- Set source of copy
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IF _record.tdcache_id_copyof IS NULL THEN
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_record.technology_name_id_copyof := _src;
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_record.tdcache_id_copyof := _record.tdcache_id;
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END IF;
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IF _record.tdcache_id_parent IS NULL THEN
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-- Set parent and dependency if there is none
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_record.tdcache_id_parent := _cache;
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_record.techdep_id := _dependency;
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ELSE
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-- Remap child nodes to the tree's copy
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SELECT INTO _record.tdcache_id_parent new_id
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FROM tdcache_copy_ids
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WHERE old_id = _record.tdcache_id_parent;
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END IF;
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-- Set depth
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_record.tdcache_depth := _record.tdcache_depth + _depth;
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-- Insert new cache entry and add mapping to temporary table
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INSERT INTO defs.techdep_cache(
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technology_name_id , tdcache_reverse , tdcache_id_parent ,
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tdcache_depth , technology_name_id_copyof ,
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tdcache_id_copyof , techdep_id
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) VALUES (
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_dest , _reverse , _record.tdcache_id_parent ,
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_record.tdcache_depth , _record.technology_name_id_copyof ,
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_record.tdcache_id_copyof , _record.techdep_id
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) RETURNING tdcache_id INTO _new_entry;
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INSERT INTO tdcache_copy_ids
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VALUES ( _record.tdcache_id , _new_entry );
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END LOOP;
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DROP TABLE tdcache_copy_ids;
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END;
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$tdcache_copy_tree$;
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REVOKE EXECUTE
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ON FUNCTION defs.tdcache_copy_tree(
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BOOLEAN , INT , INT , INT , INT , INT )
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FROM PUBLIC;
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/*
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* Add a sub-tree to all copies of some node
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* ------------------------------------------
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*
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* This function copies a source tree to all copies for a given technology and
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* direction.
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*
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* Parameters:
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* _reverse Whether the tree being copied represents reverse or
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* forward dependencies
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* _src The identifier of the technology whose dependency tree
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* needs to be copied
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* _dest The identifier of the technology onto which the source
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* tree is to be grafted
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* _dependency The identifier of the dependency because of which the
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* copy is being carried out
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*/
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DROP FUNCTION IF EXISTS defs.tdcache_set_child( BOOLEAN , INT , INT , INT );
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CREATE FUNCTION defs.tdcache_set_child(
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_reverse BOOLEAN ,
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_src INT ,
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_dest INT ,
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_dependency INT )
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RETURNS VOID
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LANGUAGE PLPGSQL
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STRICT VOLATILE
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AS $tdcache_set_child$
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DECLARE
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_tree INT;
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_entry INT;
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_depth INT;
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BEGIN
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FOR _tree , _entry , _depth IN
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SELECT technology_name_id , tdcache_id , tdcache_depth + 1
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FROM defs.techdep_cache
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WHERE tdcache_reverse = _reverse
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AND technology_name_id_copyof = _dest
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LOOP
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PERFORM defs.tdcache_copy_tree( _reverse , _src , _tree , _entry , _depth , _dependency );
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END LOOP;
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END;
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$tdcache_set_child$;
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REVOKE EXECUTE
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ON FUNCTION defs.tdcache_set_child( BOOLEAN , INT , INT , INT )
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FROM PUBLIC;
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/*
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* Trigger function that handles new technology definitions
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* ---------------------------------------------------------
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*
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* When a new technology definition is added, a pair of records needs to be
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* inserted into the dependency cache. These records correspond to the root
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* of the trees for the technology for both forward and reverse dependencies.
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*/
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DROP FUNCTION IF EXISTS defs.tgf_technologies_ai( ) CASCADE;
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CREATE FUNCTION defs.tgf_technologies_ai( )
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RETURNS TRIGGER
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LANGUAGE PLPGSQL
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STRICT VOLATILE
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SECURITY DEFINER
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AS $tgf_technologies_ai$
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BEGIN
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INSERT INTO defs.techdep_cache (
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technology_name_id , tdcache_reverse , tdcache_depth , technology_name_id_copyof
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) VALUES (
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NEW.technology_name_id , FALSE , 0 , NEW.technology_name_id
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) , (
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NEW.technology_name_id , TRUE , 0 , NEW.technology_name_id
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);
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RETURN NEW;
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END;
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$tgf_technologies_ai$;
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REVOKE EXECUTE
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ON FUNCTION defs.tgf_technologies_ai()
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FROM PUBLIC;
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CREATE TRIGGER tg_technologies_ai
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AFTER INSERT ON defs.technologies
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FOR EACH ROW EXECUTE PROCEDURE defs.tgf_technologies_ai( );
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/*
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* Trigger function that verifies new dependencies
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* ------------------------------------------------
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*
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* This trigger function locks all related trees, then check that the new
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* dependency does not lead to cycles or redundant dependencies.
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*/
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DROP FUNCTION IF EXISTS defs.tgf_techdeps_bi( ) CASCADE;
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CREATE FUNCTION defs.tgf_techdeps_bi( )
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RETURNS TRIGGER
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LANGUAGE PLPGSQL
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STRICT VOLATILE
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SECURITY DEFINER
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AS $tgf_techdeps_bi$
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BEGIN
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-- Lock all trees
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PERFORM 1
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FROM defs.techdep_cache n1
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INNER JOIN defs.techdep_cache n2
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USING ( technology_name_id )
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WHERE n1.technology_name_id_copyof IN (
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NEW.technology_name_id , NEW.technology_name_id_depends )
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FOR UPDATE OF n2;
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-- Check for cycles
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PERFORM 1 FROM defs.techdep_cache
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WHERE technology_name_id = NEW.technology_name_id
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AND technology_name_id_copyof = NEW.technology_name_id_depends
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AND tdcache_reverse;
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IF FOUND THEN
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RAISE EXCEPTION 'Cycle detected'
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USING ERRCODE = 'check_violation';
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END IF;
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-- Check for redundant dependencies
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PERFORM 1
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FROM defs.techdep_cache n1
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INNER JOIN defs.technology_dependencies d
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ON d.technology_name_id = n1.technology_name_id_copyof
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WHERE n1.technology_name_id = NEW.technology_name_id
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AND n1.tdcache_reverse
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AND d.technology_name_id_depends = NEW.technology_name_id_depends;
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IF FOUND THEN
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RAISE EXCEPTION '% is a dependency of a technology that depends on %' ,
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NEW.technology_name_id_depends , NEW.technology_name_id
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USING ERRCODE = 'check_violation';
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END IF;
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PERFORM 1
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FROM defs.technology_dependencies d1
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INNER JOIN defs.techdep_cache n
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ON n.technology_name_id = d1.technology_name_id_depends
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WHERE d1.technology_name_id = NEW.technology_name_id
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AND n.tdcache_reverse
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AND n.technology_name_id_copyof = NEW.technology_name_id_depends;
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IF FOUND THEN
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RAISE EXCEPTION '% depends on a dependency of %' ,
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NEW.technology_name_id , NEW.technology_name_id_depends
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USING ERRCODE = 'check_violation';
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END IF;
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PERFORM 1 FROM defs.techdep_cache
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WHERE technology_name_id = NEW.technology_name_id
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AND technology_name_id_copyof = NEW.technology_name_id_depends
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AND NOT tdcache_reverse;
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IF FOUND THEN
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RAISE EXCEPTION '% is already a dependency of %' ,
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NEW.technology_name_id_depends , NEW.technology_name_id
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USING ERRCODE = 'check_violation';
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END IF;
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RETURN NEW;
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END;
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$tgf_techdeps_bi$;
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CREATE TRIGGER tg_techdeps_bi
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BEFORE INSERT ON defs.technology_dependencies
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FOR EACH ROW EXECUTE PROCEDURE defs.tgf_techdeps_bi( );
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REVOKE EXECUTE
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ON FUNCTION defs.tgf_techdeps_bi( )
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FROM PUBLIC;
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/*
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* Trigger function that updates the dependency cache
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* ---------------------------------------------------
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*
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* After a new, valid dependency has been added, trees for both forward and
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* reverse depdencies must be copied.
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*/
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DROP FUNCTION IF EXISTS defs.tgf_techdeps_ai( ) CASCADE;
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CREATE FUNCTION defs.tgf_techdeps_ai( )
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RETURNS TRIGGER
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LANGUAGE PLPGSQL
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STRICT VOLATILE
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SECURITY DEFINER
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AS $tgf_techdeps_ai$
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BEGIN
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PERFORM defs.tdcache_set_child( FALSE ,
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NEW.technology_name_id_depends , NEW.technology_name_id ,
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NEW.techdep_id );
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PERFORM defs.tdcache_set_child( TRUE ,
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NEW.technology_name_id , NEW.technology_name_id_depends ,
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NEW.techdep_id );
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RETURN NEW;
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END;
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$tgf_techdeps_ai$;
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CREATE TRIGGER tg_techdeps_ai
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AFTER INSERT ON defs.technology_dependencies
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FOR EACH ROW EXECUTE PROCEDURE defs.tgf_techdeps_ai( );
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REVOKE EXECUTE
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ON FUNCTION defs.tgf_techdeps_ai( )
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FROM PUBLIC;
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