ESQL: Simplify TableIdentifier class + rename to IndexPattern (#120797)

This class is confusing: - It contains an **unused** `cluster` attribute
- we never separate out the cluster, it remains in the `index` field.
Also, in the constructor, this field is called `catalog`, which is a
concept entirely absent from ESQL at the moment. - It can refer to
multiple indices, even multiple wildcard patterns, but doesn't mention
this neither in its name nor javadoc. - It has little to do with tables,
which is likely a remnant of this class' usage in SQL, before the
`esql.core` split.

This PR removes the `cluster` attribute, renames the class to
`IndexPattern`, and adds javadoc to clarify that it can also contain
stuff like `remote1:idx1,remote-*:idx-*`.

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java

@@ -64,7 +64,7 @@
 import org.elasticsearch.xpack.esql.index.EsIndex;
 import org.elasticsearch.xpack.esql.index.IndexResolution;
 import org.elasticsearch.xpack.esql.parser.ParsingException;
-import org.elasticsearch.xpack.esql.plan.TableIdentifier;
+import org.elasticsearch.xpack.esql.plan.IndexPattern;
 import org.elasticsearch.xpack.esql.plan.logical.Aggregate;
 import org.elasticsearch.xpack.esql.plan.logical.Drop;
 import org.elasticsearch.xpack.esql.plan.logical.Enrich;
@@ -202,7 +202,9 @@ private static class ResolveTable extends ParameterizedAnalyzerRule<UnresolvedRe
         protected LogicalPlan rule(UnresolvedRelation plan, AnalyzerContext context) {
             return resolveIndex(
                 plan,
-                plan.indexMode().equals(IndexMode.LOOKUP) ? context.lookupResolution().get(plan.table().index()) : context.indexResolution()
+                plan.indexMode().equals(IndexMode.LOOKUP)
+                    ? context.lookupResolution().get(plan.indexPattern().indexPattern())
+                    : context.indexResolution()
             );
         }
 
@@ -213,20 +215,20 @@ private LogicalPlan resolveIndex(UnresolvedRelation plan, IndexResolution indexR
                     ? plan
                     : new UnresolvedRelation(
                         plan.source(),
-                        plan.table(),
+                        plan.indexPattern(),
                         plan.frozen(),
                         plan.metadataFields(),
                         plan.indexMode(),
                         indexResolutionMessage,
                         plan.commandName()
                     );
             }
-            TableIdentifier table = plan.table();
-            if (indexResolution.matches(table.index()) == false) {
+            IndexPattern table = plan.indexPattern();
+            if (indexResolution.matches(table.indexPattern()) == false) {
                 // TODO: fix this (and tests), or drop check (seems SQL-inherited, where's also defective)
                 new UnresolvedRelation(
                     plan.source(),
-                    plan.table(),
+                    plan.indexPattern(),
                     plan.frozen(),
                     plan.metadataFields(),
                     plan.indexMode(),

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/PreAnalyzer.java

@@ -51,7 +51,7 @@ protected PreAnalysis doPreAnalyze(LogicalPlan plan) {
 
         plan.forEachUp(UnresolvedRelation.class, p -> {
             List<TableInfo> list = p.indexMode() == IndexMode.LOOKUP ? lookupIndices : indices;
-            list.add(new TableInfo(p.table()));
+            list.add(new TableInfo(p.indexPattern()));
         });
         plan.forEachUp(Enrich.class, unresolvedEnriches::add);
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/TableInfo.java

@@ -7,17 +7,17 @@
 
 package org.elasticsearch.xpack.esql.analysis;
 
-import org.elasticsearch.xpack.esql.plan.TableIdentifier;
+import org.elasticsearch.xpack.esql.plan.IndexPattern;
 
 public class TableInfo {
 
-    private final TableIdentifier id;
+    private final IndexPattern id;
 
-    public TableInfo(TableIdentifier id) {
+    public TableInfo(IndexPattern id) {
         this.id = id;
     }
 
-    public TableIdentifier id() {
+    public IndexPattern id() {
         return id;
     }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/LogicalPlanBuilder.java

@@ -34,7 +34,7 @@
 import org.elasticsearch.xpack.esql.expression.Order;
 import org.elasticsearch.xpack.esql.expression.UnresolvedNamePattern;
 import org.elasticsearch.xpack.esql.expression.function.UnresolvedFunction;
-import org.elasticsearch.xpack.esql.plan.TableIdentifier;
+import org.elasticsearch.xpack.esql.plan.IndexPattern;
 import org.elasticsearch.xpack.esql.plan.logical.Aggregate;
 import org.elasticsearch.xpack.esql.plan.logical.Dissect;
 import org.elasticsearch.xpack.esql.plan.logical.Drop;
@@ -255,7 +255,7 @@ public LogicalPlan visitRowCommand(EsqlBaseParser.RowCommandContext ctx) {
     @Override
     public LogicalPlan visitFromCommand(EsqlBaseParser.FromCommandContext ctx) {
         Source source = source(ctx);
-        TableIdentifier table = new TableIdentifier(source, null, visitIndexPattern(ctx.indexPattern()));
+        IndexPattern table = new IndexPattern(source, visitIndexPattern(ctx.indexPattern()));
         Map<String, Attribute> metadataMap = new LinkedHashMap<>();
         if (ctx.metadata() != null) {
             for (var c : ctx.metadata().UNQUOTED_SOURCE()) {
@@ -468,7 +468,7 @@ public LogicalPlan visitMetricsCommand(EsqlBaseParser.MetricsCommandContext ctx)
             throw new IllegalArgumentException("METRICS command currently requires a snapshot build");
         }
         Source source = source(ctx);
-        TableIdentifier table = new TableIdentifier(source, null, visitIndexPattern(ctx.indexPattern()));
+        IndexPattern table = new IndexPattern(source, visitIndexPattern(ctx.indexPattern()));
 
         if (ctx.aggregates == null && ctx.grouping == null) {
             return new UnresolvedRelation(source, table, false, List.of(), IndexMode.STANDARD, null, "METRICS");
@@ -530,7 +530,7 @@ public PlanFactory visitJoinCommand(EsqlBaseParser.JoinCommandContext ctx) {
 
         UnresolvedRelation right = new UnresolvedRelation(
             source(target),
-            new TableIdentifier(source(target.index), null, rightPattern),
+            new IndexPattern(source(target.index), rightPattern),
             false,
             emptyList(),
             IndexMode.LOOKUP,

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/IndexPattern.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+package org.elasticsearch.xpack.esql.plan;
+
+import org.elasticsearch.xpack.esql.core.tree.Source;
+
+import java.util.Objects;
+
+/**
+ * Contains an index pattern together with its {@link Source}. Can also be a comma-separated list, like {@code idx-*,remote:other-idx*}.
+ */
+public class IndexPattern {
+
+    private final Source source;
+    private final String indexPattern;
+
+    public IndexPattern(Source source, String indexPattern) {
+        this.source = source;
+        this.indexPattern = indexPattern;
+    }
+
+    public String indexPattern() {
+        return indexPattern;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(indexPattern);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+
+        IndexPattern other = (IndexPattern) obj;
+        return Objects.equals(indexPattern, other.indexPattern);
+    }
+
+    public Source source() {
+        return source;
+    }
+
+    @Override
+    public String toString() {
+        return indexPattern;
+    }
+}

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/logical/UnresolvedRelation.java

@@ -12,7 +12,7 @@
 import org.elasticsearch.xpack.esql.core.expression.Attribute;
 import org.elasticsearch.xpack.esql.core.tree.NodeInfo;
 import org.elasticsearch.xpack.esql.core.tree.Source;
-import org.elasticsearch.xpack.esql.plan.TableIdentifier;
+import org.elasticsearch.xpack.esql.plan.IndexPattern;
 
 import java.util.Collections;
 import java.util.List;
@@ -22,7 +22,7 @@
 
 public class UnresolvedRelation extends LeafPlan implements Unresolvable {
 
-    private final TableIdentifier table;
+    private final IndexPattern indexPattern;
     private final boolean frozen;
     private final List<Attribute> metadataFields;
     /*
@@ -40,19 +40,19 @@ public class UnresolvedRelation extends LeafPlan implements Unresolvable {
 
     public UnresolvedRelation(
         Source source,
-        TableIdentifier table,
+        IndexPattern indexPattern,
         boolean frozen,
         List<Attribute> metadataFields,
         IndexMode indexMode,
         String unresolvedMessage,
         String commandName
     ) {
         super(source);
-        this.table = table;
+        this.indexPattern = indexPattern;
         this.frozen = frozen;
         this.metadataFields = metadataFields;
         this.indexMode = indexMode;
-        this.unresolvedMsg = unresolvedMessage == null ? "Unknown index [" + table.index() + "]" : unresolvedMessage;
+        this.unresolvedMsg = unresolvedMessage == null ? "Unknown index [" + indexPattern.indexPattern() + "]" : unresolvedMessage;
         this.commandName = commandName;
     }
 
@@ -68,11 +68,11 @@ public String getWriteableName() {
 
     @Override
     protected NodeInfo<UnresolvedRelation> info() {
-        return NodeInfo.create(this, UnresolvedRelation::new, table, frozen, metadataFields, indexMode, unresolvedMsg, commandName);
+        return NodeInfo.create(this, UnresolvedRelation::new, indexPattern, frozen, metadataFields, indexMode, unresolvedMsg, commandName);
     }
 
-    public TableIdentifier table() {
-        return table;
+    public IndexPattern indexPattern() {
+        return indexPattern;
     }
 
     public boolean frozen() {
@@ -124,7 +124,7 @@ public String unresolvedMessage() {
 
     @Override
     public int hashCode() {
-        return Objects.hash(source(), table, metadataFields, indexMode, unresolvedMsg);
+        return Objects.hash(source(), indexPattern, metadataFields, indexMode, unresolvedMsg);
     }
 
     @Override
@@ -138,7 +138,7 @@ public boolean equals(Object obj) {
         }
 
         UnresolvedRelation other = (UnresolvedRelation) obj;
-        return Objects.equals(table, other.table)
+        return Objects.equals(indexPattern, other.indexPattern)
             && Objects.equals(frozen, other.frozen)
             && Objects.equals(metadataFields, other.metadataFields)
             && indexMode == other.indexMode
@@ -147,11 +147,11 @@ public boolean equals(Object obj) {
 
     @Override
     public List<Object> nodeProperties() {
-        return singletonList(table);
+        return singletonList(indexPattern);
     }
 
     @Override
     public String toString() {
-        return UNRESOLVED_PREFIX + table.index();
+        return UNRESOLVED_PREFIX + indexPattern.indexPattern();
     }
 }