note 107086 modified in mongocollection.group by danbrown

Here's my code to do an equivalent of a GROUP BY and a SUM <?php $contributionCol = $db->customers->contribution; $group = $contributionCol->group(array('date' => true), array('sum' => 0), "function (obj, prev) { prev['sum'] += obj.amount; }"); ?> This groups by the 'date' column and sums over the 'amount' column. In my testing this was much slower than querying all rows and doing the Group by code with PHP. It could just be my particular setup and data set. Also at first my amount column was a string, which caused the results to be concatenated rather than arithmetic addition, something else to watch out for. --was-- Here's my code to do an equivalent of a GROUP BY and a SUM $contributionCol = $db->customers->contribution; $group = $contributionCol->group(array('date' => true), array('sum' => 0), "function (obj, prev) { prev['sum'] += obj.amount; }"); This groups by the 'date' column and sums over the 'amount' column. In my testing this was much slower than querying all rows and doing the Group by code with PHP. It could just be my particular setup and data set. Also at first my amount column was a string, which caused the results to be concatenated rather than arithmetic addition, something else to watch out for. http://php.net/manual/en/mongocollection.group.php