Loops that insert, update or delete one row per iteration pay a full round trip and a separate statement every time. It is the write-side twin of the N+1 query and just as easy to miss in review.
The fix you can use today
Use the bulk form your driver offers: executemany(), bulk_create(), COPY or a multi-row INSERT.
Batch updates with one statement and a WHERE ... IN (...) where the logic allows.
Wrap a large batch in one transaction instead of committing per row.
GreenCode researchers list one query per item among the worst energy wasters in code.
Tools that help
GreenCode Constitution skill (GreenCode researchers): open-source energy principles and a catalogue of 37 energy anti-patterns that an AI coding agent can follow to find and fix waste like this
Django Debug Toolbar: lists every SQL query a request made, so repeated queries in a loop stand out
How GreenCode helps
GreenCode helps tackle this by checking a codebase for quality, security and green software patterns in one pass. Row-by-row writes come out as ranked defects, alongside the bugs and security findings. More on this.
