Change LIKE operator case-insensitive match (#1160)

Signed-off-by: Peng Huo <penghuo@gmail.com>

core/src/main/java/org/opensearch/sql/utils/OperatorUtils.java

@@ -22,8 +22,9 @@ public class OperatorUtils {
    * @return if text matches pattern returns true; else return false.
    */
   public static ExprBooleanValue matches(ExprValue text, ExprValue pattern) {
-    return ExprBooleanValue
-        .of(Pattern.compile(patternToRegex(pattern.stringValue())).matcher(text.stringValue())
+    return ExprBooleanValue.of(
+        Pattern.compile(patternToRegex(pattern.stringValue()), Pattern.CASE_INSENSITIVE)
+            .matcher(text.stringValue())
             .matches());
   }
 

docs/user/dql/expressions.rst

@@ -149,12 +149,12 @@ Here is an example for different type of comparison operators::
 LIKE
 ----
 
-expr LIKE pattern. The expr is string value, pattern is supports literal text, a percent ( % ) character for a wildcard, and an underscore ( _ ) character for a single character match::
+expr LIKE pattern. The expr is string value, pattern is supports literal text, a percent ( % ) character for a wildcard, and an underscore ( _ ) character for a single character match, pattern is case insensitive::
 
-    os> SELECT 'axyzb' LIKE 'a%b', 'acb' LIKE 'a_b', 'axyzb' NOT LIKE 'a%b', 'acb' NOT LIKE 'a_b';
+    os> SELECT 'axyzb' LIKE 'a%b', 'acb' LIKE 'A_B', 'axyzb' NOT LIKE 'a%b', 'acb' NOT LIKE 'a_b';
     fetched rows / total rows = 1/1
     +----------------------+--------------------+--------------------------+------------------------+
-    | 'axyzb' LIKE 'a%b'   | 'acb' LIKE 'a_b'   | 'axyzb' NOT LIKE 'a%b'   | 'acb' NOT LIKE 'a_b'   |
+    | 'axyzb' LIKE 'a%b'   | 'acb' LIKE 'A_B'   | 'axyzb' NOT LIKE 'a%b'   | 'acb' NOT LIKE 'a_b'   |
     |----------------------+--------------------+--------------------------+------------------------|
     | True                 | True               | False                    | False                  |
     +----------------------+--------------------+--------------------------+------------------------+

docs/user/ppl/functions/string.rst

@@ -87,7 +87,7 @@ LIKE
 Description
 >>>>>>>>>>>
 
-Usage: like(string, PATTERN) return true if the string match the PATTERN.
+Usage: like(string, PATTERN) return true if the string match the PATTERN, PATTERN is case insensitive.
 
 There are two wildcards often used in conjunction with the LIKE operator:
 
@@ -96,7 +96,7 @@ There are two wildcards often used in conjunction with the LIKE operator:
 
 Example::
 
-    os> source=people | eval `LIKE('hello world', '_ello%')` = LIKE('hello world', '_ello%') | fields `LIKE('hello world', '_ello%')`
+    os> source=people | eval `LIKE('hello world', '_ello%')` = LIKE('hello world', '_ELLO%') | fields `LIKE('hello world', '_ello%')`
     fetched rows / total rows = 1/1
     +---------------------------------+
     | LIKE('hello world', '_ello%')   |

opensearch/src/main/java/org/opensearch/sql/opensearch/storage/script/filter/lucene/LikeQuery.java

@@ -32,6 +32,6 @@ public QueryBuilder build(FunctionExpression func) {
    */
   protected WildcardQueryBuilder createBuilder(String field, String query) {
     String matchText = StringUtils.convertSqlWildcardToLucene(query);
-    return QueryBuilders.wildcardQuery(field, matchText);
+    return QueryBuilders.wildcardQuery(field, matchText).caseInsensitive(true);
   }
 }

opensearch/src/test/java/org/opensearch/sql/opensearch/storage/script/filter/FilterQueryBuilderTest.java

@@ -132,6 +132,7 @@ void should_build_wildcard_query_for_like_expression() {
             + "  \"wildcard\" : {\n"
             + "    \"name\" : {\n"
             + "      \"wildcard\" : \"*John?\",\n"
+            + "      \"case_insensitive\" : true,\n"
             + "      \"boost\" : 1.0\n"
             + "    }\n"
             + "  }\n"
@@ -282,6 +283,7 @@ void should_use_keyword_for_multi_field_in_like_expression() {
             + "  \"wildcard\" : {\n"
             + "    \"name.keyword\" : {\n"
             + "      \"wildcard\" : \"John*\",\n"
+            + "      \"case_insensitive\" : true,\n"
             + "      \"boost\" : 1.0\n"
             + "    }\n"
             + "  }\n"