detect time series mode when resolving field names

Author: not-napoleon

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

@@ -166,4 +166,12 @@ public List<Object> nodeProperties() {
     public String toString() {
         return UNRESOLVED_PREFIX + indexPattern.indexPattern();
     }
+
+    /**
+     * @return true if and only if this relation is being loaded in "time series mode",
+     *         which changes a number of behaviors in the planner.
+     */
+    public boolean isTimeSeriesMode() {
+        return commandName.equalsIgnoreCase("TS");
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/FieldNameUtils.java

@@ -26,6 +26,7 @@
 import org.elasticsearch.xpack.esql.plan.logical.Aggregate;
 import org.elasticsearch.xpack.esql.plan.logical.Drop;
 import org.elasticsearch.xpack.esql.plan.logical.Enrich;
+import org.elasticsearch.xpack.esql.plan.logical.EsRelation;
 import org.elasticsearch.xpack.esql.plan.logical.Eval;
 import org.elasticsearch.xpack.esql.plan.logical.Filter;
 import org.elasticsearch.xpack.esql.plan.logical.Fork;
@@ -71,10 +72,19 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
             inlinestatsAggs.add(((InlineStats) i).aggregate());
         }
 
+        boolean shouldCollectAllDimensions = false;
+        // Detect if we are in TS mode
+        List<LogicalPlan> relations = parsed.collect(UnresolvedRelation.class::isInstance);
+        for (LogicalPlan i : relations) {
+            if (((UnresolvedRelation) i).isTimeSeriesMode()) {
+                shouldCollectAllDimensions = true;
+            }
+        }
+
         if (false == parsed.anyMatch(p -> shouldCollectReferencedFields(p, inlinestatsAggs))) {
             // no explicit columns selection, for example "from employees"
             // also, inlinestats only adds columns to the existent output, its Aggregate shouldn't interfere with potentially using "*"
-            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), false);
+            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), shouldCollectAllDimensions);
         }
 
         Holder<Boolean> projectAll = new Holder<>(false);
@@ -86,7 +96,7 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
         });
 
         if (projectAll.get()) {
-            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), false);
+            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), shouldCollectAllDimensions);
         }
 
         var referencesBuilder = new Holder<>(AttributeSet.builder());
@@ -221,7 +231,7 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
         parsed.forEachDownMayReturnEarly(forEachDownProcessor.get());
 
         if (projectAll.get()) {
-            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), false);
+            return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of(), shouldCollectAllDimensions);
         }
 
         // Add JOIN ON column references afterward to avoid Alias removal
@@ -235,7 +245,12 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
 
         if (fieldNames.isEmpty() && enrichPolicyMatchFields.isEmpty()) {
             // there cannot be an empty list of fields, we'll ask the simplest and lightest one instead: _index
-            return new PreAnalysisResult(enrichResolution, IndexResolver.INDEX_METADATA_FIELD, wildcardJoinIndices, false);
+            return new PreAnalysisResult(
+                enrichResolution,
+                IndexResolver.INDEX_METADATA_FIELD,
+                wildcardJoinIndices,
+                shouldCollectAllDimensions
+            );
         } else {
             fieldNames.addAll(subfields(fieldNames));
             fieldNames.addAll(enrichPolicyMatchFields);

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/session/FieldNameUtilsTests.java

@@ -18,6 +18,7 @@
 import org.elasticsearch.xpack.esql.plan.logical.Enrich;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -2969,9 +2970,23 @@ private void assertFieldNames(String query, Set<String> expected, Set<String> wi
     }
 
     private void assertFieldNames(String query, EnrichResolution enrichResolution, Set<String> expected, Set<String> wildCardIndices) {
-        var preAnalysisResult = FieldNameUtils.resolveFieldNames(parser.createStatement(query, EsqlTestUtils.TEST_CFG), enrichResolution);
+        EsqlSession.PreAnalysisResult preAnalysisResult = FieldNameUtils.resolveFieldNames(
+            parser.createStatement(query, EsqlTestUtils.TEST_CFG),
+            enrichResolution
+        );
+        assertThat("Query-wide field names", preAnalysisResult.fieldNames(), equalTo(expected));
+        assertThat("Lookup Indices that expect wildcard lookups", preAnalysisResult.wildcardJoinIndices(), equalTo(wildCardIndices));
+        assertThat(preAnalysisResult.collectAllDimensions(), equalTo(false));
+
+        // try again with TS command
+        String tsQuery = query.toLowerCase(Locale.ROOT).replaceFirst("^from", "ts");
+        if (tsQuery.equals(query)) {
+            return;
+        }
+        preAnalysisResult = FieldNameUtils.resolveFieldNames(parser.createStatement(tsQuery, EsqlTestUtils.TEST_CFG), enrichResolution);
         assertThat("Query-wide field names", preAnalysisResult.fieldNames(), equalTo(expected));
         assertThat("Lookup Indices that expect wildcard lookups", preAnalysisResult.wildcardJoinIndices(), equalTo(wildCardIndices));
+        assertThat(preAnalysisResult.collectAllDimensions(), equalTo(true));
     }
 
     private static EnrichResolution enrichResolutionWith(String enrichPolicyMatchField) {