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    <p>Here's one way to go about building the complete query step by step:</p> <ol> <li><p>Get all search events:</p> <pre><code>SELECT * FROM events AS s WHERE event = 'search' AND condition IS TRUE </code></pre></li> <li><p>Filter out those that are followed by a successful purchase event:</p> <pre><code>SELECT * FROM events AS s LEFT JOIN events AS p ON s.user = p.user AND s.session = p.session AND p.event = 'purchase' AND p.condition IS TRUE AND p.date &gt; s.date -- this assumes that `date` stores both date and time WHERE s.event = 'search' AND s.condition IS TRUE AND p.event IS NULL </code></pre></li> <li><p>Get users from the <code>users</code> table whose IDs are returned in the previous result set and whose age is above 18:</p> <pre><code>SELECT * FROM users WHERE age &gt; 18 AND user IN ( SELECT s.user FROM events AS s LEFT JOIN events AS p ON s.user = p.user AND s.session = p.session AND p.event = 'purchase' AND p.condition IS TRUE AND p.date &gt; s.date WHERE s.event = 'search' AND s.condition IS TRUE AND p.event IS NULL ) ; </code></pre></li> </ol> <p>This should give you the desired results although not necessarily in the most efficient way. You could play with the anti-join, which in this query is implemented using the <code>LEFT JOIN + WHERE IS NULL</code> technique, rewriting it with the <code>NOT EXISTS</code> one to see if that performs any better. Additionally, you could try rewriting the <code>IN</code> predicate with an equivalent <code>EXISTS</code> one. (Essentially, @Roman Pekar's first solution could be viewed as the result of both rewritings suggested.)</p>
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    1. POSelect users who did a purchase after a search where some conditions apply in PostgreSQL?
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    1. USAndriy M
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    1. COthanks for the reply. I actually improved my query using your LEFT JOIN example from point 3. Query time is not 55% percent lower :)
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      1. USAlexandru Rada
 

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