ESQL: Push == to text fields to lucene

docs/changelog/130387.yaml

@@ -0,0 +1,5 @@
+pr: 130387
+summary: Push `==` to `text` fields to lucene
+area: ES|QL
+type: enhancement
+issues: []

plugins/mapper-annotated-text/src/main/java/org/elasticsearch/index/mapper/annotatedtext/AnnotatedTextFieldMapper.java

@@ -492,7 +492,7 @@ private AnnotatedTextFieldType(
             KeywordFieldMapper.KeywordFieldType syntheticSourceDelegate,
             Map<String, String> meta
         ) {
-            super(name, true, store, tsi, isSyntheticSource, syntheticSourceDelegate, meta, false, false);
+            super(name, true, store, tsi, isSyntheticSource, syntheticSourceDelegate, meta, false, false, false);
         }
 
         public AnnotatedTextFieldType(String name, Map<String, String> meta) {

server/src/main/java/org/elasticsearch/index/mapper/TextFieldMapper.java

@@ -67,6 +67,7 @@
 import org.elasticsearch.index.fielddata.SourceValueFetcherSortedBinaryIndexFieldData;
 import org.elasticsearch.index.fielddata.StoredFieldSortedBinaryIndexFieldData;
 import org.elasticsearch.index.fielddata.plain.PagedBytesIndexFieldData;
+import org.elasticsearch.index.query.MatchQueryBuilder;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.index.similarity.SimilarityProvider;
 import org.elasticsearch.script.field.DelegateDocValuesField;
@@ -413,7 +414,8 @@ private TextFieldType buildFieldType(
                     SyntheticSourceHelper.syntheticSourceDelegate(fieldType, multiFields),
                     meta.getValue(),
                     eagerGlobalOrdinals.getValue(),
-                    indexPhrases.getValue()
+                    indexPhrases.getValue(),
+                    matchQueryYieldsCandidateMatchesForEquality()
                 );
                 if (fieldData.getValue()) {
                     ft.setFielddata(true, freqFilter.getValue());
@@ -422,6 +424,25 @@ private TextFieldType buildFieldType(
             return ft;
         }
 
+        /**
+         * Does a `match` query generate all valid candidates for `==`? Meaning,
+         * if I do a match query for any string, say `foo bar baz`, then that
+         * query will find all documents that indexed the same string.
+         * <p>
+         *     This should be true for most sanely configured text fields. That's
+         *     just how we use them for search. But it's quite possible to make
+         *     the index analyzer not agree with the search analyzer, for example.
+         * </p>
+         * <p>
+         *     So this implementation is ultra-paranoid.
+         * </p>
+         */
+        private boolean matchQueryYieldsCandidateMatchesForEquality() {
+            return index.getValue() == Boolean.TRUE
+                && analyzers.indexAnalyzer.isConfigured() == false
+                && analyzers.searchAnalyzer.isConfigured() == false;
+        }
+
         private SubFieldInfo buildPrefixInfo(MapperBuilderContext context, FieldType fieldType, TextFieldType tft) {
             if (indexPrefixes.get() == null) {
                 return null;
@@ -694,6 +715,12 @@ public static class TextFieldType extends StringFieldType {
          */
         private final KeywordFieldMapper.KeywordFieldType syntheticSourceDelegate;
 
+        /**
+         * Does a {@link MatchQueryBuilder} produce <strong>all</strong> documents
+         * that <strong>might</strong> have equal text to the query's value.
+         */
+        private final boolean matchQueryYieldsCandidateMatchesForEquality;
+
         public TextFieldType(
             String name,
             boolean indexed,
@@ -703,7 +730,8 @@ public TextFieldType(
             KeywordFieldMapper.KeywordFieldType syntheticSourceDelegate,
             Map<String, String> meta,
             boolean eagerGlobalOrdinals,
-            boolean indexPhrases
+            boolean indexPhrases,
+            boolean matchQueryYieldsCandidateMatchesForEquality
         ) {
             super(name, indexed, stored, false, tsi, meta);
             fielddata = false;
@@ -712,6 +740,7 @@ public TextFieldType(
             this.syntheticSourceDelegate = syntheticSourceDelegate;
             this.eagerGlobalOrdinals = eagerGlobalOrdinals;
             this.indexPhrases = indexPhrases;
+            this.matchQueryYieldsCandidateMatchesForEquality = matchQueryYieldsCandidateMatchesForEquality;
         }
 
         public TextFieldType(String name, boolean indexed, boolean stored, Map<String, String> meta) {
@@ -728,6 +757,7 @@ public TextFieldType(String name, boolean indexed, boolean stored, Map<String, S
             syntheticSourceDelegate = null;
             eagerGlobalOrdinals = false;
             indexPhrases = false;
+            matchQueryYieldsCandidateMatchesForEquality = true;
         }
 
         public TextFieldType(String name, boolean isSyntheticSource) {
@@ -740,7 +770,8 @@ public TextFieldType(String name, boolean isSyntheticSource) {
                 null,
                 Collections.emptyMap(),
                 false,
-                false
+                false,
+                true
             );
         }
 
@@ -1030,6 +1061,10 @@ public boolean canUseSyntheticSourceDelegateForQueryingEquality(String str) {
             return str.length() <= syntheticSourceDelegate.ignoreAbove();
         }
 
+        public boolean matchQueryYieldsCandidateMatchesForEquality() {
+            return matchQueryYieldsCandidateMatchesForEquality;
+        }
+
         @Override
         public BlockLoader blockLoader(BlockLoaderContext blContext) {
             if (canUseSyntheticSourceDelegateForLoading()) {
@@ -1219,7 +1254,7 @@ public KeywordFieldMapper.KeywordFieldType syntheticSourceDelegate() {
     public static class ConstantScoreTextFieldType extends TextFieldType {
 
         public ConstantScoreTextFieldType(String name, boolean indexed, boolean stored, TextSearchInfo tsi, Map<String, String> meta) {
-            super(name, indexed, stored, tsi, false, null, meta, false, false);
+            super(name, indexed, stored, tsi, false, null, meta, false, false, /* unused */ false);
         }
 
         public ConstantScoreTextFieldType(String name) {

x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/lucene/read/ValuesSourceReaderOperatorTests.java

@@ -1538,6 +1538,7 @@ private TextFieldMapper.TextFieldType storedTextField(String name) {
             null,
             Map.of(),
             false,
+            false,
             false
         );
     }
@@ -1552,6 +1553,7 @@ private TextFieldMapper.TextFieldType textFieldWithDelegate(String name, Keyword
             delegate,
             Map.of(),
             false,
+            false,
             false
         );
     }