Query is faster with additional JOIN Announcing the arrival of Valued Associate #679: Cesar...
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Query is faster with additional JOIN
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)SQL Server Join/where processing orderWhy do aggregate functions alter the way my rows are fetched?Are JOINs on non-indexed columns faster than sub-queries?Optimizing multi-table left joinsShould I use left join to do my job in this scenario?MySQL: Why queries with subqueries are much faster than single query?How to improve query count execution with mySql replicate?How does LEFT JOIN with WHERE clause works?Which Query of JOIN with DISTINCT & JOIN with Subquery has better Performance?Counting unique (distinct) users per day
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}
SELECT COUNT(DISTINCT User_id) FROM Session
GROUP BY Floor_id;
SELECT COUNT(DISTINCT User_id) FROM Session
JOIN Floor ON Floor.id = Floor_id
GROUP BY Floor_id;
The second query runs 20x faster than the first query.
Floor_id is a FK to Floor.id.
Why is this the case and how should we know when we can make use of JOINs to speed up queries?
mysql join mysql-5.7 count
asked 3 mins ago
Avery235Avery235
1164
add a comment |
SELECT COUNT(DISTINCT User_id) FROM Session
GROUP BY Floor_id;
SELECT COUNT(DISTINCT User_id) FROM Session
JOIN Floor ON Floor.id = Floor_id
GROUP BY Floor_id;
The second query runs 20x faster than the first query.
Floor_id is a FK to Floor.id.
Why is this the case and how should we know when we can make use of JOINs to speed up queries?
mysql join mysql-5.7 count
asked 3 mins ago
Avery235Avery235
1164
add a comment |
SELECT COUNT(DISTINCT User_id) FROM Session
GROUP BY Floor_id;
SELECT COUNT(DISTINCT User_id) FROM Session
JOIN Floor ON Floor.id = Floor_id
GROUP BY Floor_id;
The second query runs 20x faster than the first query.
Floor_id is a FK to Floor.id.
Why is this the case and how should we know when we can make use of JOINs to speed up queries?
mysql join mysql-5.7 count
asked 3 mins ago
Avery235Avery235
1164
SELECT COUNT(DISTINCT User_id) FROM Session
GROUP BY Floor_id;
SELECT COUNT(DISTINCT User_id) FROM Session
JOIN Floor ON Floor.id = Floor_id
GROUP BY Floor_id;
The second query runs 20x faster than the first query.
Floor_id is a FK to Floor.id.
Why is this the case and how should we know when we can make use of JOINs to speed up queries?
mysql join mysql-5.7 count
mysql join mysql-5.7 count
asked 3 mins ago
Avery235Avery235
1164
asked 3 mins ago
Avery235Avery235
1164
asked 3 mins ago
Avery235Avery235
1164
asked 3 mins ago
Avery235Avery235
1164
asked 3 mins ago
Avery235Avery235
1164
1164
add a comment |
add a comment |
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