From 9b7b56f871f6437c43aa23f1c0a6c02233e4f6dd Mon Sep 17 00:00:00 2001
From: Fang Xing <155562079+fang-xing-esql@users.noreply.github.com>
Date: Wed, 2 Jul 2025 13:14:19 -0400
Subject: [PATCH] [ESQL] Ensure date/date_nanos implicit casting rule behind
 snapshot (#130026)

* put date date_nanos implicit casting rule behind snapshot
---
 docs/changelog/127797.yaml                    |  6 ---
 .../xpack/esql/analysis/Analyzer.java         | 48 +++++++++++++------
 2 files changed, 34 insertions(+), 20 deletions(-)
 delete mode 100644 docs/changelog/127797.yaml

diff --git a/docs/changelog/127797.yaml b/docs/changelog/127797.yaml
deleted file mode 100644
index 8fca3da004130..0000000000000
--- a/docs/changelog/127797.yaml
+++ /dev/null
@@ -1,6 +0,0 @@
-pr: 127797
-summary: "Date nanos implicit casting in union types option #2"
-area: ES|QL
-type: enhancement
-issues:
- - 110009
diff --git a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java
index e9f57b92ede28..1c27446903615 100644
--- a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java
+++ b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java
@@ -130,6 +130,7 @@
 import static java.util.Collections.singletonList;
 import static org.elasticsearch.common.logging.LoggerMessageFormat.format;
 import static org.elasticsearch.xpack.core.enrich.EnrichPolicy.GEO_MATCH_TYPE;
+import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.IMPLICIT_CASTING_DATE_AND_DATE_NANOS;
 import static org.elasticsearch.xpack.esql.core.type.DataType.BOOLEAN;
 import static org.elasticsearch.xpack.esql.core.type.DataType.DATETIME;
 import static org.elasticsearch.xpack.esql.core.type.DataType.DATE_NANOS;
@@ -168,7 +169,7 @@ public class Analyzer extends ParameterizedRuleExecutor<LogicalPlan, AnalyzerCon
             new ResolveInference(),
             new ResolveLookupTables(),
             new ResolveFunctions(),
-            new DateMillisToNanosInEsRelation()
+            new DateMillisToNanosInEsRelation(IMPLICIT_CASTING_DATE_AND_DATE_NANOS.isEnabled())
         ),
         new Batch<>(
             "Resolution",
@@ -1692,23 +1693,42 @@ private static LogicalPlan planWithoutSyntheticAttributes(LogicalPlan plan) {
      * Cast the union typed fields in EsRelation to date_nanos if they are mixed date and date_nanos types.
      */
     private static class DateMillisToNanosInEsRelation extends Rule<LogicalPlan, LogicalPlan> {
+
+        private final boolean isSnapshot;
+
+        DateMillisToNanosInEsRelation(boolean isSnapshot) {
+            this.isSnapshot = isSnapshot;
+        }
+
         @Override
         public LogicalPlan apply(LogicalPlan plan) {
-            return plan.transformUp(EsRelation.class, relation -> {
-                if (relation.indexMode() == IndexMode.LOOKUP) {
-                    return relation;
-                }
-                return relation.transformExpressionsUp(FieldAttribute.class, f -> {
-                    if (f.field() instanceof InvalidMappedField imf && imf.types().stream().allMatch(DataType::isDate)) {
-                        HashMap<ResolveUnionTypes.TypeResolutionKey, Expression> typeResolutions = new HashMap<>();
-                        var convert = new ToDateNanos(f.source(), f);
-                        imf.types().forEach(type -> typeResolutions(f, convert, type, imf, typeResolutions));
-                        var resolvedField = ResolveUnionTypes.resolvedMultiTypeEsField(f, typeResolutions);
-                        return new FieldAttribute(f.source(), f.parentName(), f.name(), resolvedField, f.nullable(), f.id(), f.synthetic());
+            if (isSnapshot) {
+                return plan.transformUp(EsRelation.class, relation -> {
+                    if (relation.indexMode() == IndexMode.LOOKUP) {
+                        return relation;
                     }
-                    return f;
+                    return relation.transformExpressionsUp(FieldAttribute.class, f -> {
+                        if (f.field() instanceof InvalidMappedField imf && imf.types().stream().allMatch(DataType::isDate)) {
+                            HashMap<ResolveUnionTypes.TypeResolutionKey, Expression> typeResolutions = new HashMap<>();
+                            var convert = new ToDateNanos(f.source(), f);
+                            imf.types().forEach(type -> typeResolutions(f, convert, type, imf, typeResolutions));
+                            var resolvedField = ResolveUnionTypes.resolvedMultiTypeEsField(f, typeResolutions);
+                            return new FieldAttribute(
+                                f.source(),
+                                f.parentName(),
+                                f.name(),
+                                resolvedField,
+                                f.nullable(),
+                                f.id(),
+                                f.synthetic()
+                            );
+                        }
+                        return f;
+                    });
                 });
-            });
+            } else {
+                return plan;
+            }
         }
     }