Unbounded Result Guard

A query returned FIFTY ROWS IN DEVELOPMENT. Nothing about it changed. In production it returns FIVE MILLION, because the table grew and nothing in the query ever bounded how many rows it could hand back.

THE SYMPTOM. The process runs out of memory. Or a request that used to take 40ms now takes 40 seconds. You go look at the query in the logs and it looks completely ordinary -- maybe there is even a LIMIT right there in the text. Nothing errored. Nothing warned. The query has been silently doing this since the day the table crossed some size nobody picked on purpose.

A LIMIT IN THE TEXT IS NOT A BOUND. A LIMIT applied after a join can still require the whole join to be materialised first. A LIMIT inside a subquery bounds the subquery, not the result. A LIMIT with no ORDER BY bounds the count and not the content, which is a different bug that shows up as flaky pagination. And a query bounded only by a WHERE clause on a column that grows is bounded by nothing at all.

This decides which of those a given query is, and says which fact makes it so. It REFUSES rather than guessing when the shape cannot be determined from what it was given -- because 'it has a LIMIT, it is fine' is exactly the reasoning that ships this to production.

VERIFIED: 61 tests, measured by running the suite.

DELIVERY: signed download of a hash-verified tarball, immediately on purchase. Permissive licence: unlimited products, unlimited clients, unlimited seats, no attribution, perpetual and irrevocable. One restriction, do not republish the source as source.

Interface

What you call, and what comes back. Types and signatures only — the implementation ships with the source.

  export function createState(): AnalyzeState;
  export function analyzeFromSource(source: FromSource, ctx: Ctx, path: string, state: AnalyzeState): SourceBound;
  export function analyzeQuery(node: QueryNode, ctx: Ctx, path: string, state: AnalyzeState): SourceBound;
  export function createRootContext(): Ctx;
  export function analyzeBoundedness(query: QueryNode): BoundednessReport;
  export function withinAcceptableCap(report: BoundednessReport, acceptableCap: number): CapCheck;
  export function worseVerdict(a: BoundedVerdict, b: BoundedVerdict): BoundedVerdict;
  export function combineVerdicts(verdicts: readonly BoundedVerdict[]): BoundedVerdict;
  export function isNonNegativeInteger(n: number): boolean;

  export type BoundedVerdict = "bounded" | "unbounded" | "not-determinable";
  export type JoinType = "inner" | "left" | "right" | "full" | "cross";
  export type JoinFanout = "one-to-one" | { maxPerRow: number } | "unbounded" | "unknown";
  export type FromSource = | { kind: "table";
  export type SetOperationKind = "union" | "unionAll" | "intersect" | "except";
  export type QueryNode = SelectNode | SetOperationNode;