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try to fix create_triggers
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dullbananas
GitHub
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commit
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1 changed files with 123 additions and 141 deletions
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@ -36,74 +36,105 @@ BEGIN
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END
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$$;
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-- Create functions that select both old and new rows in a trigger. Column 1 is `-1` if old and `1` if new,
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-- which can be used with `sum` to get the number to add to a count. Column 2 is the original row as a composite
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-- value. A separate function is called in each `IF` statement to prevent an error from referencing transition
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-- tables that don't exist. All of this could be one function, but that would require using `RETURN QUERY EXECUTE`
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-- instead of calls to separate functions because of PostgreSQL's limited polymorphism. Parsing and planning dynamic
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-- queries at runtime is worse for performance.
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CREATE PROCEDURE r.combine_transition_tables_function (table_name text)
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-- This function creates statement-level triggers for all operation types. It's designed this way
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-- because of these limitations:
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-- * A trigger that uses transition tables can only handle 1 operation type.
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-- * Transition tables must be relevant for the operation type (for example, `NEW TABLE` is
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-- not allowed for a `DELETE` trigger)
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-- * Transition tables are only provided to the trigger function, not to functions that it calls.
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--
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-- This function can only be called once per table. The command to run is given as the 2nd argument
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-- and has access to these tables:
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-- * `old_table` with old rows
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-- * `new_table` with new rows
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-- * `combined_transition_tables` with both old and new rows, with 2 columns:
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-- 1. `-1` for old rows and `1` for new rows, which can be used with `sum` to get the number
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-- to add to a count
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-- 2. the old or new row as a composite value
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CREATE PROCEDURE r.create_triggers (table_name text, command text)
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LANGUAGE plpgsql
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AS $a$
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DECLARE
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defs text := $b$
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CREATE FUNCTION r.thing_delete_statement ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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PERFORM (
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WITH
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combined_transition_tables AS (
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select_old_table
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),
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trigger_result AS command
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SELECT
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1
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);
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RETURN NULL;
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END
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$$;
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CREATE TRIGGER delete_statement
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AFTER DELETE ON thing REFERENCING OLD TABLE AS old_table
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.thing_delete_statement ();
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CREATE FUNCTION r.thing_insert_statement ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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PERFORM (
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WITH
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combined_transition_tables AS (
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select_new_table
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),
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trigger_result AS command
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SELECT
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1
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);
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RETURN NULL;
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END
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$$;
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CREATE TRIGGER insert_statement
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AFTER DELETE ON thing REFERENCING NEW TABLE AS new_table
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.thing_insert_statement ();
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CREATE FUNCTION r.thing_update_statement ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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PERFORM (
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WITH
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combined_transition_tables AS (
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select_old_table
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UNION ALL
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select_new_table
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),
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trigger_result AS command
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SELECT
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1
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);
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RETURN NULL;
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END
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$$;
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CREATE TRIGGER update_statement
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AFTER UPDATE ON thing REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.thing_update_statement ();
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$b$;
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BEGIN
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EXECUTE replace($b$
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CREATE FUNCTION r.get_old_thing_rows ()
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RETURNS SETOF record
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LANGUAGE plpgsql
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AS $$
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BEGIN
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RETURN QUERY SELECT -1, old_table FROM old_table;
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RETURN;
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END
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$$;
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CREATE FUNCTION r.get_new_thing_rows ()
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RETURNS SETOF record
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LANGUAGE plpgsql
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AS $$
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BEGIN
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RETURN QUERY SELECT 1, new_table FROM new_table;
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RETURN;
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END
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$$;
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CREATE FUNCTION r.combine_thing_transition_tables (tg_op text)
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RETURNS SETOF record
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LANGUAGE plpgsql
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AS $$
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BEGIN
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IF (TG_OP IN ('UPDATE', 'DELETE')) THEN
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RETURN QUERY SELECT * FROM r.get_old_thing_rows () AS (count_diff bigint, thing thing);
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END IF;
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IF (TG_OP IN ('UPDATE', 'INSERT')) THEN
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RETURN QUERY SELECT * FROM r.get_new_thing_rows () AS (count_diff bigint, thing thing);
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END IF;
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RETURN;
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END
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$$;
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$b$, 'thing', table_name);
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defs := replace(defs, 'select_old_table', $$
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SELECT -1 AS count_diff, old_table AS thing FROM old_table
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$$);
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defs := replace(defs, 'select_new_table', $$
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SELECT 1 AS count_diff, new_table AS thing FROM new_table
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$$);
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defs := replace(defs, 'thing', table_name);
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defs := replace(defs, 'command', format('(%s)', command));
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EXECUTE defs;
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END
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$a$;
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CALL r.combine_transition_tables_function('comment');
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CALL r.combine_transition_tables_function('community');
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CALL r.combine_transition_tables_function('community_follower');
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CALL r.combine_transition_tables_function('person');
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CALL r.combine_transition_tables_function('post');
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-- Creates triggers for all operation types, which can't be 1 trigger when transition tables are used
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CREATE PROCEDURE r.create_triggers (table_name text, function_name text)
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LANGUAGE plpgsql
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AS $$
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BEGIN
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EXECUTE format('CREATE TRIGGER %2$s_insert AFTER INSERT ON %1$s REFERENCING NEW TABLE AS new_table FOR EACH STATEMENT EXECUTE FUNCTION r.%2$s ();', table_name, function_name);
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EXECUTE format('CREATE TRIGGER %2$s_delete AFTER DELETE ON %1$s REFERENCING OLD TABLE AS old_table FOR EACH STATEMENT EXECUTE FUNCTION r.%2$s ();', table_name, function_name);
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EXECUTE format('CREATE TRIGGER %2$s_update AFTER UPDATE ON %1$s REFERENCING OLD TABLE AS old_table NEW TABLE AS new_table FOR EACH STATEMENT EXECUTE FUNCTION r.%2$s ();', table_name, function_name);
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END
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$$;
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-- Define functions
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CREATE FUNCTION r.creator_id_from_post_aggregates (agg post_aggregates)
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RETURNS int RETURN agg.creator_id;
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@ -149,12 +180,8 @@ BEGIN
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.resolve_reports_when_thing_removed ( );
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-- When a thing gets a vote, update its aggregates and its creator's aggregates
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CREATE FUNCTION r.thing_aggregates_from_like ( )
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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WITH thing_diff AS (
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CALL r.create_triggers ('thing_like', $$
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WITH thing_diff AS (
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UPDATE
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thing_aggregates AS a
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SET
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@ -168,7 +195,7 @@ BEGIN
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sum(count_diff) FILTER (WHERE (thing_like).score = 1) AS upvotes,
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sum(count_diff) FILTER (WHERE (thing_like).score != 1) AS downvotes
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FROM
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r.combine_thing_transition_tables (TG_OP)
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combined_transition_tables
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AS (count_diff bigint,
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thing_like thing_like)
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GROUP BY
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@ -191,13 +218,8 @@ BEGIN
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GROUP BY
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creator_id) AS diff
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WHERE
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a.person_id = diff.creator_id;
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RETURN NULL;
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END $$;
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CALL r.create_triggers ('thing_like', 'thing_aggregates_from_like');
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$b$,
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'thing',
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thing_type);
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a.person_id = diff.creator_id
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$$);
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END
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$a$;
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@ -206,11 +228,7 @@ CALL r.post_or_comment ('post');
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CALL r.post_or_comment ('comment');
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-- Create triggers that update counts in parent aggregates
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CREATE FUNCTION r.parent_aggregates_from_comment ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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CALL r.create_triggers('comment', $$
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WITH comment_group AS (
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SELECT
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(comment).post_id,
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@ -218,7 +236,7 @@ BEGIN
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(comment).local,
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sum(count_diff) AS comments
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FROM
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r.combine_comment_transition_tables (TG_OP)
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combined_transition_tables
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AS (count_diff bigint,
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comment comment)
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WHERE
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@ -302,18 +320,10 @@ FROM (
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GROUP BY
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community_id) AS diff
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WHERE
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a.community_id = diff.community_id;
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RETURN NULL;
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END
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$$;
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a.community_id = diff.community_id
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$$);
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CALL r.create_triggers ('comment', 'parent_aggregates_from_comment');
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CREATE FUNCTION r.parent_aggregates_from_post ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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CALL r.create_triggers('post', $$
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WITH post_group AS (
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SELECT
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(post).community_id,
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@ -321,7 +331,7 @@ BEGIN
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(post).local,
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sum(count_diff) AS posts
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FROM
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r.combine_post_transition_tables (TG_OP)
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combined_post_transition_tables
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AS (count_diff bigint,
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post post)
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WHERE
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@ -357,18 +367,10 @@ SET
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FROM
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post_group
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WHERE
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a.community_id = post_group.community_id;
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RETURN NULL;
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END
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$$;
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a.community_id = post_group.community_id
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$$);
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CALL r.create_triggers ('post', 'parent_aggregates_from_post');
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CREATE FUNCTION r.site_aggregates_from_community ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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CALL r.create_triggers('community', $$
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UPDATE
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site_aggregates AS a
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SET
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@ -377,20 +379,12 @@ BEGIN
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SELECT
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sum(count_diff) AS communities
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FROM
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r.combine_community_transition_tables (TG_OP)
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combined_transition_tables
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AS (count_diff bigint, community community)
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WHERE (community).local AND NOT ((community).deleted OR (community).removed)) AS diff;
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RETURN NULL;
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END
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$$;
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WHERE (community).local AND NOT ((community).deleted OR (community).removed)) AS diff
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$$);
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CALL r.create_triggers ('community', 'site_aggregates_from_community');
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CREATE FUNCTION r.site_aggregates_from_person ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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CALL r.create_triggers('person', $$
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UPDATE
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site_aggregates AS a
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SET
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@ -399,14 +393,10 @@ BEGIN
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SELECT
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sum(count_diff) AS users
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FROM
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r.combine_person_transition_tables (TG_OP)
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combined_transition_tables
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AS (count_diff bigint, person person)
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WHERE (person).local) AS diff;
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RETURN NULL;
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END
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$$;
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CALL r.create_triggers ('person', 'site_aggregates_from_person');
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WHERE (person).local) AS diff
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$$);
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-- For community_aggregates.comments, don't include comments of deleted or removed posts
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CREATE FUNCTION r.update_comment_count_from_post ()
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@ -456,11 +446,7 @@ CREATE TRIGGER comment_count
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EXECUTE FUNCTION r.update_comment_count_from_post ();
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-- Count subscribers for local communities
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CREATE FUNCTION r.community_aggregates_from_subscriber ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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AS $$
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BEGIN
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CALL r.create_triggers ('community_follower', $$
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UPDATE
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community_aggregates AS a
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SET
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@ -470,7 +456,7 @@ BEGIN
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(community_follower).community_id,
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sum(count_diff) AS subscribers
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FROM
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r.combine_community_follower_transition_tables (TG_OP)
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combine_transition_tables
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AS (count_diff bigint, community_follower community_follower)
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WHERE (
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SELECT
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@ -483,12 +469,8 @@ BEGIN
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GROUP BY
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(community_follower).community_id) AS diff
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WHERE
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a.community_id = diff.community_id;
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RETURN NULL;
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END
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$$;
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CALL r.create_triggers ('community_follower', 'community_aggregates_from_subscriber');
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a.community_id = diff.community_id
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$$);
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-- These triggers create and update rows in each aggregates table to match its associated table's rows.
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-- Deleting rows and updating IDs are already handled by `CASCADE` in foreign key constraints.
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@ -581,6 +563,11 @@ BEGIN
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END
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$$;
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CREATE TRIGGER aggregates
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AFTER INSERT ON post REFERENCING NEW TABLE AS new_post
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.post_aggregates_from_post ();
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CREATE FUNCTION r.post_aggregates_from_post_update ()
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RETURNS TRIGGER
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LANGUAGE plpgsql
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@ -599,11 +586,6 @@ BEGIN
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END
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$$;
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CREATE TRIGGER aggregates
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AFTER INSERT ON post REFERENCING NEW TABLE AS new_post
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FOR EACH STATEMENT
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EXECUTE FUNCTION r.post_aggregates_from_post ();
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CREATE TRIGGER aggregates_update
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AFTER UPDATE ON post REFERENCING NEW TABLE AS new_post
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FOR EACH STATEMENT
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