Package org.elasticsearch.xpack.esql.view

Class ViewCompaction

java.lang.Object

org.elasticsearch.xpack.esql.rule.Rule<LogicalPlan,LogicalPlan>

org.elasticsearch.xpack.esql.view.ViewCompaction

public class ViewCompaction
extends Rule<LogicalPlan,LogicalPlan>

Compacts the nested plan produced by ViewResolver into the form expected by the rest of the query pipeline. The work is split into two phases so that ViewShadowRelation siblings (CPS lenient lookups) survive long enough to be paired with their strict UnresolvedRelation sibling at field-caps time:

1. preIndexResolution(LogicalPlan) — runs from EsqlSession before PreAnalyzer. Reshapes user-written Subquery/UnionAll structures into ViewUnionAll so the analyzer sees a uniform tree shape. Leaves shadows in place; leaves nested ViewUnionAlls nested. The UnresolvedRelation index patterns it leaves in the tree are exactly what PreAnalyzer hands to field-caps and what ResolveTable later looks up.
2. postIndexResolution(LogicalPlan) — runs as an analyzer rule after ResolveTable. Strips any ViewShadowRelation that lenient field-caps did not fold into a sibling EsRelation (in Phase A this is all of them, since lenient field-caps is not yet wired up — see esql-planning#543), then flattens nested ViewUnionAlls and unwraps remaining NamedSubquery wrappers.

The split is what lets a colleague implement lenient field-caps purely as a Phase B analyzer rule that lives between ResolveTable and postIndexResolution(org.elasticsearch.xpack.esql.plan.logical.LogicalPlan): shadows that match remote indices get rewritten to UnresolvedRelation/EsRelation; shadows that fail to match are simply left unresolved and postIndexResolution(org.elasticsearch.xpack.esql.plan.logical.LogicalPlan) sweeps them away. Ordering details: see esql-planning#472.

Note: a small amount of compaction stays inside ViewResolver.buildPlanFromBranches(org.elasticsearch.xpack.esql.plan.logical.UnresolvedRelation, java.util.List<org.elasticsearch.xpack.esql.view.ViewResolver.ViewPlan>, int) — specifically the per-level sibling UnresolvedRelation merge — to keep the resolved tree compact at the per-level boundary, so wide branching levels of compactable views (e.g. FROM v1, v2, ... v9) collapse to a single UnresolvedRelation rather than tripping Fork.MAX_BRANCHES at post-analysis verification.

Field Summary

Fields inherited from class org.elasticsearch.xpack.esql.rule.Rule

log

Constructor Summary

Constructors

Constructor	Description
ViewCompaction()

Method Summary

Modifier and Type	Method	Description
LogicalPlan	apply(LogicalPlan plan)	Backward-compatible helper: runs preIndexResolution(LogicalPlan) followed by postIndexResolution(LogicalPlan).
static LogicalPlan	postIndexResolution(LogicalPlan plan)	Phase 2, runs as an analyzer rule after ResolveTable.
static LogicalPlan	preIndexResolution(LogicalPlan plan)	Phase 1, runs before PreAnalyzer.

Methods inherited from class org.elasticsearch.xpack.esql.rule.Rule

name, toString, typeToken

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

ViewCompaction

public ViewCompaction()

Method Details

apply

public LogicalPlan apply(LogicalPlan plan)

Backward-compatible helper: runs preIndexResolution(LogicalPlan) followed by postIndexResolution(LogicalPlan). Production code calls the two phases separately; tests that exercise the compaction logic without going through the full analyzer call this to get the same end state as the live pipeline produces.

Specified by:

apply in class Rule<LogicalPlan,LogicalPlan>

preIndexResolution

public static LogicalPlan preIndexResolution(LogicalPlan plan)

Phase 1, runs before PreAnalyzer. Reshapes user-written Subquery/ UnionAll structures into ViewUnionAll for uniform downstream handling. Deliberately does NOT strip ViewShadowRelation siblings or flatten nested ViewUnionAlls — those are deferred to postIndexResolution(org.elasticsearch.xpack.esql.plan.logical.LogicalPlan) so lenient field-caps (Phase B) can pair each shadow with its strict resolution at field-caps time.

postIndexResolution

public static LogicalPlan postIndexResolution(LogicalPlan plan)

Phase 2, runs as an analyzer rule after ResolveTable. Strips ViewShadowRelation siblings that lenient field-caps did not resolve, then flattens nested ViewUnionAll structures and unwraps remaining NamedSubquery wrappers. By the time this runs, all reachable UnresolvedRelations have been replaced by EsRelations, so the UnresolvedRelation-merge step inside compactNestedViewUnionAlls(org.elasticsearch.xpack.esql.plan.logical.LogicalPlan) is effectively a no-op — sibling EsRelations stay separate (Strategy A from esql-planning#543).