This is one of the BEFORE triggers that inserts into the right table partition:
CREATE OR REPLACE FUNCTION public.insert_install_session()
RETURNS trigger
LANGUAGE plpgsql
AS
$body$
BEGIN
IF (NEW.created >= '2015-10-01 00:00:00' AND NEW.created < '2015-10-02 00:00:00') THEN
INSERT INTO install_session_2015_10_01 VALUES (NEW.*);
ELSIF (NEW.created >= '2015-10-02 00:00:00' AND NEW.created < '2015-10-03 00:00:00') THEN
INSERT INTO install_session_2015_10_02 VALUES (NEW.*);
ELSIF (NEW.created >= '2015-09-30 00:00:00' AND NEW.created < '2015-10-01 00:00:00') THEN
INSERT INTO install_session_2015_09_30 VALUES (NEW.*);
ELSE
RETURN NEW;
END IF;
RETURN NULL;
END;
$body$
CREATE TRIGGER trigger_insert_install_session
BEFORE INSERT ON install_session
FOR EACH ROW EXECUTE PROCEDURE insert_install_session
and I have a query that uses RETURNING:
INSERT INTO "install_session"
(<columns here>)
VALUES
(<values here>)
RETURNING "install_session"."id";
How can I make the RETURNING work? It seems it always returns NULL.
Is it because of the RETURN NULL at the end of the function? I can't return NEW because the row would be inserted a second time, no? Here is the official docs.
This is not going to work with a trigger solution. You could make it work with rules instead of triggers IIRC, but that has other caveats ...
However, to just get the auto-generated ID from a serial column, you can call currval() immediately after the command in the same session:
SELECT currval('name_of_your_id_sequence_here'::regclass);
Or even just lastval() - if respective id columns in the partitions are not inherited (don't share the same sequence).
SELECT lastval('name_of_your_id_sequence_here'::regclass);
You can use pg_get_serial_sequence() to find the name of the sequence if you don't know it:
SELECT currval(pg_get_serial_sequence('install_session', 'id'));
Related answer on dba.SE:
Return ID from partitioned table in postgres?
Related
I was to populate a field is_continued_post if some conditions are true about the previously inserted row into the table (it's the same user, and it's inserted_at is less than N mins from the new rows inserted_at).
When a new comment is inserted into the database. I want to get the last comment (with the same post_id) that was inserted, then check that the old rows user_id are the same as the new rows user_id, and that the old row was inserted less than 2 mins before the new row. If this is true, I want to flip a boolean on the new row to true before inserting it.
Is this possible with Postgresql triggers? Or is there a better way to do this?
This is what I've come up with so far:
CREATE OR REPLACE FUNCTION update_message_cont()
RETURNS trigger AS $$
BEGIN
old := (SELECT m0.user_id, m0.inserted_at FROM messages AS m0 WHERE (m0.post_id = NEW.post_id) ORDER BY m0.inserted_at DESC LIMIT 1);
NEW.is_continued := CASE
WHEN old is NULL THEN FALSE
WHEN old.user_id = NEW.user_id AND ((NEW.inserted_at - old.inserted_at) < 120) THEN TRUE
END;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
Yes, that is possible, but only if you have a column in the table that allows you to identify the last inserted row. The order of insertion is not reflected in the table as such.
So introduce a column
inserted_at timestamp with time zone DEFAULT clock_timestamp() NOT NULL
An index on (post_id, inserted_at) will make the query fast.
The whole trigger could look like:
CREATE FUNCTION update_message_cont() RETURNS trigger AS
$$BEGIN
SELECT user_id IS NOT DISTINCT FROM NEW.user_id INTO NEW.is_continued
FROM messages
WHERE post_id = NEW.post_id
AND inserted_at > NEW.inserted_at - INTERVAL '120 seconds'
ORDER BY inserted_at DESC
LIMIT 1;
-- if no previous row was found:
IF NEW.is_continued IS NULL THEN
NEW.is_continued = FALSE;
END IF;
RETURN NEW;
END;$$ LANGUAGE plpgsql;
CREATE TRIGGER update_message_cont BEFORE INSERT ON messages
FOR EACH ROW EXECUTE PROCEDURE update_message_cont();
I'm trying to implement table partitioning with dynamic table creation using BEFORE INSERT trigger to create new tables and indexes when necesarry using following solution:
create table mylog (
mylog_id serial not null primary key,
ts timestamp(0) not null default now(),
data text not null
);
CREATE OR REPLACE FUNCTION mylog_insert() RETURNS trigger AS
$BODY$
DECLARE
_name text;
_from timestamp(0);
_to timestamp(0);
BEGIN
SELECT into _name 'mylog_'||replace(substring(date_trunc('day', new.ts)::text from 0 for 11), '-', '');
IF NOT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name=_name) then
SELECT into _from date_trunc('day', new.ts)::timestamp(0);
SELECT into _to _from + INTERVAL '1 day';
EXECUTE 'CREATE TABLE '||_name||' () INHERITS (mylog)';
EXECUTE 'ALTER TABLE '||_name||' ADD CONSTRAINT ts_check CHECK (ts >= '||quote_literal(_from)||' AND ts < '||quote_literal(_to)||')';
EXECUTE 'CREATE INDEX '||_name||'_ts_idx on '||_name||'(ts)';
END IF;
EXECUTE 'INSERT INTO '||_name||' (ts, data) VALUES ($1, $2)' USING
new.ts, new.data;
RETURN null;
END;
$BODY$
LANGUAGE plpgsql;
CREATE TRIGGER mylog_insert
BEFORE INSERT
ON mylog
FOR EACH ROW
EXECUTE PROCEDURE mylog_insert();
Everything works as expected but each day when concurrent INSERT statements are being fired for the first time that day, one of them fails trying to "create table that already exists". I suspect that this is caused by the triggers being fired concurrently and both trying to create new table and only one can succeed.
I could be using CREATE TABLE IF NOT EXIST but I cannot detect the outcome so I cannot reliably create constraints and indexes.
What can I do to avoid such problem? Is there any way to signal the fact that the table has been already created to other concurrent triggers? Or maybe there is a way of knowing if CREATE TABLE IF NOT EXISTS created new table or not?
What I do is create a pgAgent job to run every day and create 3 months of tables ahead of time.
CREATE OR REPLACE FUNCTION avl_db.create_alltables()
RETURNS numeric AS
$BODY$
DECLARE
rec record;
BEGIN
FOR rec IN
SELECT date_trunc('day', i::timestamp without time zone) as table_day
FROM generate_series(now()::date,
now()::date + '3 MONTH'::interval,
'1 DAY'::interval) as i
LOOP
PERFORM avl_db.create_table (rec.table_day);
END LOOP;
PERFORM avl_db.avl_partition(now()::date,
now()::date + '3 MONTH'::interval);
RETURN 0;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION avl_db.create_alltables()
OWNER TO postgres;
create_table is very similar to your CREATE TABLE code
avl_partition update the BEFORE INSERT TRIGGER but I saw you do that part with dynamic query. Will have to check again that.
Also I see you are doing inherit, but you are missing a very important CONSTRAINT
CONSTRAINT route_sources_20170601_event_time_check CHECK (
event_time >= '2017-06-01 00:00:00'::timestamp without time zone
AND event_time < '2017-06-02 00:00:00'::timestamp without time zone
)
This improve the query a lot when doing a search for event_time because doesn't have to check every table.
See how doesn't check all tables for the month:
Eventually I wrapped CREATE TABLE in BEGIN...EXCEPTION block that catches duplicate_table exception - this did the trick, but creating the tables upfront in a cronjob is much better approach performance-wise.
CREATE OR REPLACE FUNCTION mylog_insert() RETURNS trigger AS
$BODY$
DECLARE
_name text;
_from timestamp(0);
_to timestamp(0);
BEGIN
SELECT into _name 'mylog_'||replace(substring(date_trunc('day', new.ts)::text from 0 for 11), '-', '');
IF NOT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name=_name) then
SELECT into _from date_trunc('day', new.ts)::timestamp(0);
SELECT into _to _from + INTERVAL '1 day';
BEGIN
EXECUTE 'CREATE TABLE '||_name||' () INHERITS (mylog)';
EXECUTE 'ALTER TABLE '||_name||' ADD CONSTRAINT ts_check CHECK (ts >= '||quote_literal(_from)||' AND ts < '||quote_literal(_to)||')';
EXECUTE 'CREATE INDEX '||_name||'_ts_idx on '||_name||'(ts)';
EXCEPTION WHEN duplicate_table THEN
RAISE NOTICE 'table exists -- ignoring';
END;
END IF;
EXECUTE 'INSERT INTO '||_name||' (ts, data) VALUES ($1, $2)' USING
new.ts, new.data;
RETURN null;
END;
$BODY$
LANGUAGE plpgsql;
I have a log_table in my db that is partitioned according to partitioning docs. I have a function that inserts records to partition table depending on date and a trigger that calls that function, like in the documentation.
Trigger example
CREATE TRIGGER insert_measurement_trigger
BEFORE INSERT ON measurement
FOR EACH ROW EXECUTE PROCEDURE measurement_insert_trigger();
Function example
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.logdate >= DATE '2006-02-01' AND
NEW.logdate < DATE '2006-03-01' ) THEN
INSERT INTO measurement_y2006m02 VALUES (NEW.*);
ELSIF ( NEW.logdate >= DATE '2006-03-01' AND
NEW.logdate < DATE '2006-04-01' ) THEN
INSERT INTO measurement_y2006m03 VALUES (NEW.*);
...
ELSIF ( NEW.logdate >= DATE '2008-01-01' AND
NEW.logdate < DATE '2008-02-01' ) THEN
INSERT INTO measurement_y2008m01 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Fix the measurement_insert_trigger() function!';
END IF;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
I am using openjpa 2.3.0 as the JPA implementation.
With trigger on the table
When i try to persist new entity in transaction to this log_table
with trigger, I get an exception on commiting:
Caused by: <openjpa-2.3.0-r422266:1540826 nonfatal store error> org.apache.openjpa.persistence.OptimisticLockException:
An optimistic lock violation was detected when flushing object instance "...entities.LogTable#67ec8ef4" to the data store.
This indicates that the object was concurrently modified in another transaction.
When I insert one record manualy using INSERT it works, but returns
Query returned successfully: 0 rows affected, 54 ms execution time.
Without the trigger on table
It works OK using the same java code that throwed the exception, so the code should be ok. I do nothing exceptional for persisting the entity.
The manual INSERT command returns
Query returned successfully: one row affected, 51 ms execution time.
Can this difference in number of affected rows be the reason why openjpa cannot handle this correctly? On the code mentioned in the exception, I found this
try {
int count = executeUpdate(stmnt, sql, row);
if (count != 1) {
logSQLWarnings(stmnt);
Object failed = row.getFailedObject();
if (failed != null)
_exceptions.add(new OptimisticException(failed));
...
It seems that because with the trigger the insert return 0 affected rows instead of 1, the code evaluates it as exceptional.
SUBQUESTION
IS there a way to make the trigger result behave the same? I mean that it would return that 1 row was affected? Somehow propagate the result from the inner function?
I have the same problem using Java Ebean ORM. Inserting on java side causing Optimization lock error because of failing rowCount.
My Research into this problem did not lend a solution, i.e propogating row count from insert into child table or hacking the row count functionality.
My Solution (After your conditions, change NEW.id to next sequence in table and RETURN NEW that will cause insert into parent table) and give you the tuple response you need to affect row_count.
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.logdate >= DATE '2006-02-01' AND
NEW.logdate < DATE '2006-03-01' ) THEN
INSERT INTO measurement_y2006m02 VALUES (NEW.*);
ELSIF ( NEW.logdate >= DATE '2006-03-01' AND
NEW.logdate < DATE '2006-04-01' ) THEN
INSERT INTO measurement_y2006m03 VALUES (NEW.*);
...
ELSIF ( NEW.logdate >= DATE '2008-01-01' AND
NEW.logdate < DATE '2008-02-01' ) THEN
INSERT INTO measurement_y2008m01 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Fix the measurement_insert_trigger() function!';
END IF;
--ORIGINAL CODE
--RETURN NULL
------------------NEW CODE-----------------
NEW.id = nextval('table_id_seq');
RETURN NEW;
END;
$$
LANGUAGE plpgsql;
Yes for a moment we do have duplicate entries that have 2 different ids. So hopefully no unique constraints on parent table exist. If they do you might have to remove them. We need to delete the duplicate on parent table.
Create Function that will return trigger to be used after insert. Trigger will delete the NEW row inserted into parent table measurement.
CREATE OR REPLACE FUNCTION measurement_after_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
EXECUTE 'DELETE FROM measurement where measurement.id = ' || NEW.id;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
Lastly
Add After INSERT Trigger to parent table measurement
CREATE TRIGGER measurement_after_insert_trigger_delete_entry
AFTER INSERT ON measurement
FOR EACH ROW EXECUTE PROCEDURE measurement_after_insert_trigger();
I did consider another possible solution to this was to just have raw sql due the insert. Just did not like that approach as I would have to make sure all future constructors route to the raw sql. Approach above will allow the code to behave as expected as if this was just a regular table we were inserting to.
This is my first time using triggers in green plum environment. I think I have most of it setup but I am facing some issues when I insert data. Here is my trigger
CREATE TRIGGER insert_trigger
BEFORE INSERT ON leads.abhi_temp
FOR EACH ROW EXECUTE PROCEDURE leads.my_trigger();
Here is the definition of the trigger
CREATE OR REPLACE FUNCTION leads.my_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.date >= DATE '2003-01-01' AND
NEW.date < DATE '2003-12-31' ) THEN
INSERT INTO leads.abhi_temp_y2003 VALUES (NEW.*);
ELSIF ( NEW.date >= DATE '2004-01-01' AND
NEW.date < DATE '2004-12-31' ) THEN
INSERT INTO leads.abhi_temp_y2004 VALUES (NEW.*);
END IF;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
Now to insert data into my table I use
insert into leads.myData (select column1, column2 from leads.someOtherDara where column1 = '1');
But this gives me an error
ERROR: function cannot execute on segment because it issues a non-SELECT statement (functions.c:133)
I think the error is because I am using nested queries to insert data. Not sure how to fix this. Any recommendation. Thanks in advance for your help
I am aware, There is very limited support for triggers in Greenplum, It does not support DML operations.
May i know how do you achieve this, i mean how the rules can be applied as u said in your previous comments
I am referring to http://www.if-not-true-then-false.com/2009/11/howto-create-postgresql-table-partitioning-part-1/
To reproduce the problem, here is some simple steps to follow :
(1) create database named "tutorial"
(2) perform the following SQL query :
CREATE TABLE impressions_by_day (
advertiser_id SERIAL NOT NULL,
day DATE NOT NULL DEFAULT CURRENT_DATE,
impressions INTEGER NOT NULL,
PRIMARY KEY (advertiser_id, day)
);
CREATE OR REPLACE FUNCTION insert_table()
RETURNS void AS
$BODY$DECLARE
_impressions_by_day impressions_by_day;
BEGIN
INSERT INTO impressions_by_day(impressions ) VALUES(888) RETURNING * INTO _impressions_by_day;
RAISE NOTICE 'After insert, the returned advertiser_id is %', _impressions_by_day.advertiser_id;
END;$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION insert_table() OWNER TO postgres;
(3) create database named "tutorial_partition"
(4) perform the following SQL query :
CREATE TABLE impressions_by_day (
advertiser_id SERIAL NOT NULL,
day DATE NOT NULL DEFAULT CURRENT_DATE,
impressions INTEGER NOT NULL,
PRIMARY KEY (advertiser_id, day)
);
CREATE OR REPLACE FUNCTION insert_table()
RETURNS void AS
$BODY$DECLARE
_impressions_by_day impressions_by_day;
BEGIN
INSERT INTO impressions_by_day(impressions ) VALUES(888) RETURNING * INTO _impressions_by_day;
RAISE NOTICE 'After insert, the returned advertiser_id is %', _impressions_by_day.advertiser_id;
END;$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION insert_table() OWNER TO postgres;
CREATE TABLE impressions_by_day_y2010m1ms2 (
PRIMARY KEY (advertiser_id, day),
CHECK ( day >= DATE '2010-01-01' AND day < DATE '2010-03-01' )
) INHERITS (impressions_by_day);
CREATE INDEX impressions_by_day_y2010m1ms2_index ON impressions_by_day_y2010m1ms2 (day);
CREATE OR REPLACE FUNCTION impressions_by_day_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.day >= DATE '2010-01-01' AND NEW.day < DATE '2010-03-01' ) THEN
INSERT INTO impressions_by_day_y2010m1ms2 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Something wrong with the impressions_by_day_insert_trigger() function!';
END IF;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER insert_impressions_by_day_trigger
BEFORE INSERT ON impressions_by_day
FOR EACH ROW EXECUTE PROCEDURE impressions_by_day_insert_trigger();
(5) execute
SELECT * FROM insert_table() on tutorial
We get
NOTICE: After insert, the returned advertiser_id is 1
(6) execute
SELECT * FROM insert_table() on tutorial_partition
We get
NOTICE: After insert, the returned advertiser_id is
How is it possible to get advertiser_id is 1 too, in tutorial_partition?
The trigger is passing back NULL, which indicates to the INSERT that no action is to be performed. Since no action is performed, the RETURNING * clause returns nothing. You're not going to be able to intercept (and override) the INSERT and use RETURNING in the same operation and get anything meaningful.