Another reason postgres could be running very slow, is that it may be spooling the intermediate result to a temp file on hard disk. Do you see a performance increase when using SSD Drives?
One of the reasons you are seeing that the subquery runs twice as fast on most of the databases ( like SQL server, oracle & MySQL), is that it is able to execute the query with one pass through of the data. When it is…
Another reason postgres could be running very slow, is that it may be spooling the intermediate result to a temp file on hard disk. Do you see a performance increase when using SSD Drives?
One of the reasons you are seeing that the subquery runs twice as fast on most of the databases ( like SQL server, oracle & MySQL), is that it is able to execute the query with one pass through of the data. When it is…