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Author: pawankartik-elastic

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

@@ -132,7 +132,8 @@ protected static void validateClusterString(String clusterString, EsqlBaseParser
     /**
      * Takes the parsed constituent strings and validates them.
      * @param clusterString Name of the remote cluster. Can be null.
-     * @param indexPattern Name of the index or pattern; can also have multiple patterns in case of quoting, e.g. {@code FROM """index*,-index1"""}.
+     * @param indexPattern Name of the index or pattern; can also have multiple patterns in case of quoting,
+     *                     e.g. {@code FROM """index*,-index1"""}.
      * @param selectorString Selector string, i.e. "::data" or "::failures". Can be null.
      * @param ctx Index Pattern Context for generating error messages with offsets.
      * @param hasSeenStar If we've seen an asterisk so far.
@@ -158,7 +159,7 @@ private static void validate(
         String[] patterns;
         if (clusterString == null && selectorString == null) {
             // Pattern could be quoted or is singular like "index_name".
-            patterns = indexPattern.split(",");
+            patterns = indexPattern.split(",", -1);
         } else {
             // Either of cluster string or selector string is present. Pattern is unquoted.
             patterns = new String[] { indexPattern };
@@ -169,11 +170,11 @@ private static void validate(
             throwInvalidIndexNameException(indexPattern, BLANK_INDEX_ERROR_MESSAGE, ctx);
         }
 
-        // Edge case: happens when all the index names in a pattern are empty.
+        // Edge case: happens when all the index names in a pattern are empty like "FROM ",,,,,"".
         if (patterns.length == 0) {
             throwInvalidIndexNameException(indexPattern, BLANK_INDEX_ERROR_MESSAGE, ctx);
         } else if (patterns.length == 1) {
-            // Pattern is an unquoted string.
+            // Pattern is either an unquoted string or a quoted string with a single index (no comma sep).
             validateSingleIndexPattern(clusterString, patterns[0], selectorString, ctx, hasSeenStar);
         } else {
             /*

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/parser/StatementParserTests.java

@@ -3180,6 +3180,10 @@ public void testInvalidFromPatterns() {
         expectError(randomFrom(sourceCommands) + " \",,, \"", indexIsBlank);
         expectError(randomFrom(sourceCommands) + " \", , ,,\"", indexIsBlank);
         expectError(randomFrom(sourceCommands) + " \",,,\",*", indexIsBlank);
+        expectError(randomFrom(sourceCommands) + " \"*,\"", indexIsBlank);
+        expectError(randomFrom(sourceCommands) + " \"*,,,\"", indexIsBlank);
+        expectError(randomFrom(sourceCommands) + " \"index1,,,,\"", indexIsBlank);
+        expectError(randomFrom(sourceCommands) + " \"index1,index2,,\"", indexIsBlank);
         expectError(randomFrom(sourceCommands) + " \"index1,<-+^,index2\",*", "must not contain the following characters");
         expectError(randomFrom(sourceCommands) + " \"\",*", indexIsBlank);
         expectError(randomFrom(sourceCommands) + " \"*: ,*,\"", indexIsBlank);