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Rule priority, scope & exceptions

Use this to align rules with the senior-level structure (P0/P1/P2, scope, exceptions/tradeoffs).

PriorityP1 — maintainability, architecture, long-term qualityScopeUniversal — language-agnostic, broadly applicable

Exceptions / tradeoffs (EN)Iznimke / tradeoffi (HR)

backend ruleP1universalStack: sql

sqlperformancejoinsdatabase

Apply filtering conditions in the JOIN ON clause rather than joining then discarding rows

When a join should only match rows meeting a condition, put that condition in the JOIN ON clause instead of joining everything and filtering afterwards, which is wasteful.

PR: hegnar-investor-ws · org-mining-2026-06Created: Jun 17, 2026

Bad example

Old codesql

1	`JOIN tickers t ON th.ticker_id = t.id`
2	`WHERE t.millistream_id IS NOT NULL -- joins rows we then throw away`

Explanation (EN)

Objašnjenje (HR)

Good example

New codesql

1	`JOIN tickers t ON th.ticker_id = t.id AND t.millistream_id IS NOT NULL`

Explanation (EN)

Objašnjenje (HR)

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