Better performance in MySQL subqueries for timeline graph - mysql

Question

i have a query with subqueries for a timeline widget of participants, leads and customers.
For example with 15k rows in the table but only 2k in this date range (January 1st to January 28th) this takes about 40 seconds!
SELECT created_at as date,
(
SELECT COUNT(id)
FROM participant
WHERE created_at <= date
) as participants,
(
SELECT COUNT(DISTINCT id)
FROM participant
WHERE participant_type = "lead"
AND created_at <= date
) as leads,
(
SELECT COUNT(DISTINCT id)
FROM participant
WHERE participant_type = "customer"
AND created_at <= date
) as customer
FROM participant
WHERE created_at >= '2016-01-01 00:00:00'
AND created_at <= '2016-01-28 23:59:59'
GROUP BY date(date)
How can i improve the performance?
The table fields are declared as follows:
id => primary_key, INT 10, auto increment
participant_type => ENUM "lead,customer", NULLABLE, ut8_unicode_ci
created_at => TIMESTAMP, default '0000-00-00 00:00:00'

Answer 1

Possibly try using conditions within the counts (or sums) to get the values you want, having cross joined things:-
SELECT a.created_at as date,
SUM(IF(b.created_at <= a.created_at, 1, 0)) AS participants,
COUNT(DISTINCT IF(b.participant_type = "lead" AND b.created_at <= a.created_at, b.id, NULL)) AS leads,
COUNT(DISTINCT IF(b.participant_type = "customer" AND b.created_at <= a.created_at, b.id, NULL)) AS customer
FROM participant a
CROSS JOIN participant b
WHERE a.created_at >= '2016-01-01 00:00:00'
AND a.created_at <= '2016-01-28 23:59:59'
GROUP BY date(date)
or maybe move the date check into the join
SELECT a.created_at as date,
COUNT(b.id) AS participants,
COUNT(DISTINCT IF(b.participant_type = "lead", b.id, NULL)) AS leads,
COUNT(DISTINCT IF(b.participant_type = "customer", b.id, NULL)) AS customer
FROM participant a
LEFT OUTER JOIN participant b
ON b.created_at <= a.created_at
WHERE a.created_at >= '2016-01-01 00:00:00'
AND a.created_at <= '2016-01-28 23:59:59'
GROUP BY date(date)

Answer 2

I'm not clearly understanding what you want to do with this query. But may I can provide way for optimization.
Try this one:
SELECT
participants.day as day,
participants.total_count,
leads.lead_count,
customer.customer_count
FROM
(
SELECT created_at as day, COUNT(id) as total_count
FROM participant
WHERE created_at BETWEEN '2016-01-01 00:00:00' AND '2016-01-28 23:59:59'
GROUP BY day
) as participants
LEFT JOIN
(
SELECT created_at as day, COUNT(DISTINCT id) as lead_count
FROM participant
WHERE participant_type = "lead"
AND created_at BETWEEN '2016-01-01 00:00:00' AND '2016-01-28 23:59:59'
GROUP BY day
) as leads ON (participants.day = leads.day)
LEFT JOIN
(
SELECT created_at as day, COUNT(DISTINCT id) as customer_count
FROM participant
WHERE participant_type = "customer"
AND WHERE created_at BETWEEN '2016-01-01 00:00:00' AND '2016-01-28 23:59:59'
GROUP BY day
) as customer ON (participants.day = customer.day)

Answer 3

Add index to the query. You can execute Explain on this query.
With the help of EXPLAIN, you can see where you should add indexes to tables so that the statement executes faster by using indexes to find rows.