Improve minTransportVersion over multiple field-caps calls

Author: craigtaverner

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

@@ -521,10 +521,6 @@ public void analyzedPlan(
 
         PreAnalyzer.PreAnalysis preAnalysis = preAnalyzer.preAnalyze(parsed);
         PreAnalysisResult result = FieldNameUtils.resolveFieldNames(parsed, preAnalysis.enriches().isEmpty() == false);
-        if (preAnalysis.indexes().isEmpty()) {
-            // Happens with no main indices, e.g. ROW a = 1 (even if there are lookup indices, but views and sub-queries will not lead here)
-            result = result.withMinimumTransportVersion(TransportVersion.current());
-        }
         String description = requestFilter == null ? "the only attempt without filter" : "first attempt with filter";
 
         resolveIndicesAndAnalyze(
@@ -866,7 +862,6 @@ private void preAnalyzeMainIndices(
             // return empty resolution if the expression is pure CCS and resolved no remote clusters (like no-such-cluster*:index)
             listener.onResponse(
                 result.withIndices(indexPattern, IndexResolution.valid(new EsIndex(indexPattern.indexPattern(), Map.of(), Map.of())))
-                    .withMinimumTransportVersion(TransportVersion.current())
             );
         } else {
             IndexMode indexMode = preAnalysis.indexes().get(indexPattern);
@@ -1024,7 +1019,7 @@ public record PreAnalysisResult(
     ) {
 
         public PreAnalysisResult(Set<String> fieldNames, Set<String> wildcardJoinIndices) {
-            this(fieldNames, wildcardJoinIndices, Map.of(), new HashMap<>(), null, InferenceResolution.EMPTY, null);
+            this(fieldNames, wildcardJoinIndices, Map.of(), new HashMap<>(), null, InferenceResolution.EMPTY, TransportVersion.current());
         }
 
         PreAnalysisResult withIndices(IndexPattern indexPattern, IndexResolution indices) {
@@ -1071,6 +1066,12 @@ PreAnalysisResult withInferenceResolution(InferenceResolution inferenceResolutio
         }
 
         PreAnalysisResult withMinimumTransportVersion(TransportVersion minimumTransportVersion) {
+            if (this.minimumTransportVersion != null) {
+                if (this.minimumTransportVersion.equals(minimumTransportVersion)) {
+                    return this;
+                }
+                minimumTransportVersion = TransportVersion.min(this.minimumTransportVersion, minimumTransportVersion);
+            }
             return new PreAnalysisResult(
                 fieldNames,
                 wildcardJoinIndices,