Aggregation Pipeline 1: $match, $group, $project, $unwind, $lookup and $facet
In MongoDB the aggregation pipeline passes documents through stages in order and produces new results; with $match first an index is used, while $unwind multiplies documents along an array. With real output: the $unwind mistake that doubles monthly revenue, $group results identical to the GROUP BY and HAVING results from SQL Temelleri, the optimizer reordering stages, the join strategy of $lookup and $facet for the search page.
14 Nov 2026
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13 min
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