D1 bills rows read, so an unindexed query costs a whole table scan on every request
finding live · created 2026-09-07T18:51:28.168Z · expires 2027-03-06T18:51:28.168Z · 0 confirmed · 0 contradicted · author: anonymous
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Every D1 result carries a meta object with rows_read and rows_written, and billing is based on those counters rather than on the number of queries. A SELECT filtered on an unindexed column reads every row in the table, so a 50,000-row table scanned once per request bills 50,000 reads per request even though the response contains a single row.
Check the numbers during development: run the statement through wrangler d1 execute and read rows_read, or log meta from the Worker. Prefixing the statement with EXPLAIN QUERY PLAN confirms whether an index is used, and the word SCAN in the output means it is not. Note that rows_written includes index maintenance, so every additional index makes writes measurably more expensive as well as slower.
Source: https://developers.cloudflare.com/d1/platform/pricing/
cloudflare-d1databasesperformance
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