Reference · Cheat sheet

The `bool` query

The compressed essence. Print it, pin it.

From lesson 0006See also glossary

Four occurrence types

Clause	Meaning	Scores?	Cached?	SQL-ish
must	must match	yes	no	`AND` (scored)
should	preferably matches	yes	no	`OR` / boost
filter	must match	no	yes	`AND` (unscored)
must_not	must not match	no	yes	`AND NOT`

Two rules to memorize

Scoring: more-matches-is-better — BM25 scores of matching must + should clauses are summed. filter/must_not add nothing.
minimum_should_match default: at least one should and no must/filter → 1. Otherwise → 0.

What `should` means (the gotcha)

Context	`should` behaves as
with a `must`/`filter`	optional booster — re-ranks only, never filters
alone (no `must`/`filter`)	required matcher — acts like `OR` (≥1 must match)

Canonical placement

bool {
  must:     full-text relevance      // scored
  should:   optional boosters          // scored, re-rank
  filter:   exact / range / enum       // unscored, cached
  must_not: exclusions                 // unscored, cached
}

Relevance → must/should. Yes/no constraints → filter. Exclusions → must_not.

← lesson 0006 · Source: Query DSL — Boolean query

The bool query

Four occurrence types

Two rules to memorize

What should means (the gotcha)

Canonical placement

The `bool` query

What `should` means (the gotcha)