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Not counting duplicates of declared pratition in OVER()-clause - Mailing list pgsql-sql

From	Andreas Joseph Krogh
Subject	Not counting duplicates of declared pratition in OVER()-clause
Date	November 28, 2017 23:54:47
Msg-id	VisenaEmail.e1.e756ac5c250cdc14.16003bb2e74@tc7-visena Whole thread Raw
Responses	Sv: Not counting duplicates of declared pratition in OVER()-clause
List	pgsql-sql

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Hi.

I'm trying to prevent duplicate values from being part of SUM().

(complete schema with INSERTs below)

I have this query to count all log-entries per activity per month in a sub-query, then adding a value from another table in the outer query, which I'd then like to sum but only count values from the same month once:

SELECT info.*, stuff.value + info.total_for_month AS new_value    , SUM(stuff.value + info.total_for_month) OVER () AS total_new_value_sum
FROM (         SELECT DISTINCT
               date_trunc('month', log.start_date::TIMESTAMP WITHOUT TIME ZONE) AS month
             , log.activity_id             , count(log.entity_id) OVER(partition by date_trunc('month', log.start_date::TIMESTAMP WITHOUT TIME ZONE), log.activity_id) AS num_logs_per_activity             , count(log.entity_id) OVER (partition by date_trunc('month', log.start_date::TIMESTAMP WITHOUT TIME ZONE)) AS total_for_month         FROM
             log_entry log
         ORDER BY date_trunc('month', log.start_date::TIMESTAMP WITHOUT TIME ZONE) ASC, log.activity_id ASC
     ) AS info
    LEFT OUTER JOIN stuff ON info.month = stuff.month
;

What I want is this result:

month	activity_id	num_logs_per_activity	total_for_month	new_value	total_new_value_sum
2017-01-01 00:00:00.000000	1	4	8	30	141
2017-01-01 00:00:00.000000	2	4	8	30	141
2017-02-01 00:00:00.000000	1	10	12	111	141
2017-02-01 00:00:00.000000	2	2	12	111	141
2017-03-01 00:00:00.000000	1	1	1	NULL	141

But what I get is:

month	activity_id	num_logs_per_activity	total_for_month	new_value	total_new_value_sum
2017-01-01 00:00:00.000000	1	4	8	30	282
2017-01-01 00:00:00.000000	2	4	8	30	282
2017-02-01 00:00:00.000000	1	10	12	111	282
2017-02-01 00:00:00.000000	2	2	12	111	282
2017-03-01 00:00:00.000000	1	1	1	NULL	282

The problem is I don't know how to prevent every values in "new_value"-column from being included in the SUM().

I'd like something like this:

    , SUM(stuff.value + info.total_for_month) <distinct by month> AS total_new_value_sum

Any hints on how to accomplish this?

Here is the complete schema:

DROP TABLE IF EXISTS stuff;
DROP TABLE IF EXISTS log_entry;
CREATE TABLE log_entry(    entity_id SERIAL PRIMARY KEY,    start_date DATE NOT NULL,    activity_id BIGINT NOT NULL,    logged_for BIGINT NOT NULL
);

CREATE TABLE stuff(    entity_id SERIAL PRIMARY KEY,    month DATE NOT NULL UNIQUE,    value INTEGER NOT NULL
);

INSERT INTO log_entry(start_date, activity_id, logged_for)
VALUES ('2017-01-01', 1, 5)    , ('2017-01-02', 1, 5)    , ('2017-01-03', 2, 5)    , ('2017-01-04', 2, 5)    , ('2017-02-01', 1, 5)    , ('2017-02-01', 2, 5)    , ('2017-02-01', 1, 5)    , ('2017-02-02', 1, 5)    , ('2017-02-02', 1, 5)    , ('2017-02-03', 1, 5)    , ('2017-01-01', 1, 6)    , ('2017-01-02', 1, 6)    , ('2017-01-03', 2, 6)    , ('2017-01-04', 2, 6)    , ('2017-02-01', 1, 6)    , ('2017-02-01', 2, 6)    , ('2017-02-01', 1, 6)    , ('2017-02-02', 1, 6)    , ('2017-02-02', 1, 6)    , ('2017-02-03', 1, 6)    , ('2017-03-01', 1, 6);

INSERT INTO stuff(month, value) VALUES('2017-01-01', 22),('2017-02-01', 99);