diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
index 6510bacf55899..a14ae540f5056 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
@@ -65,12 +65,16 @@ object StringUtils extends Logging {
     "(?s)" + out.result() // (?s) enables dotall mode, causing "." to match new lines
   }
 
-  private[this] val trueStrings = Set("t", "true", "y", "yes", "1").map(UTF8String.fromString)
-  private[this] val falseStrings = Set("f", "false", "n", "no", "0").map(UTF8String.fromString)
+  // "true", "yes", "1", "false", "no", "0", and unique prefixes of these strings are accepted.
+  private[this] val trueStrings =
+    Set("true", "tru", "tr", "t", "yes", "ye", "y", "on", "1").map(UTF8String.fromString)
+
+  private[this] val falseStrings =
+    Set("false", "fals", "fal", "fa", "f", "no", "n", "off", "of", "0").map(UTF8String.fromString)
 
   // scalastyle:off caselocale
-  def isTrueString(s: UTF8String): Boolean = trueStrings.contains(s.toLowerCase)
-  def isFalseString(s: UTF8String): Boolean = falseStrings.contains(s.toLowerCase)
+  def isTrueString(s: UTF8String): Boolean = trueStrings.contains(s.toLowerCase.trim())
+  def isFalseString(s: UTF8String): Boolean = falseStrings.contains(s.toLowerCase.trim())
   // scalastyle:on caselocale
 
   /**
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
index 1f9fa22d30e13..65d13c9aad6f6 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
@@ -819,20 +819,34 @@ class CastSuite extends SparkFunSuite with ExpressionEvalHelper {
   }
 
   test("cast string to boolean") {
-    checkCast("t", true)
     checkCast("true", true)
+    checkCast("tru", true)
+    checkCast("tr", true)
+    checkCast("t", true)
     checkCast("tRUe", true)
-    checkCast("y", true)
+    checkCast("    tRue   ", true)
+    checkCast("    tRu   ", true)
     checkCast("yes", true)
+    checkCast("ye", true)
+    checkCast("y", true)
     checkCast("1", true)
+    checkCast("on", true)
 
-    checkCast("f", false)
     checkCast("false", false)
-    checkCast("FAlsE", false)
-    checkCast("n", false)
+    checkCast("fals", false)
+    checkCast("fal", false)
+    checkCast("fa", false)
+    checkCast("f", false)
+    checkCast("    fAlse    ", false)
+    checkCast("    fAls    ", false)
+    checkCast("    FAlsE    ", false)
     checkCast("no", false)
+    checkCast("n", false)
     checkCast("0", false)
+    checkCast("off", false)
+    checkCast("of", false)
 
+    checkEvaluation(cast("o", BooleanType), null)
     checkEvaluation(cast("abc", BooleanType), null)
     checkEvaluation(cast("", BooleanType), null)
   }
diff --git a/sql/core/src/test/resources/sql-tests/inputs/pgSQL/boolean.sql b/sql/core/src/test/resources/sql-tests/inputs/pgSQL/boolean.sql
index 4427d76f48d80..178823bcfe9d6 100644
--- a/sql/core/src/test/resources/sql-tests/inputs/pgSQL/boolean.sql
+++ b/sql/core/src/test/resources/sql-tests/inputs/pgSQL/boolean.sql
@@ -22,7 +22,6 @@ SELECT false AS `false`;
 
 SELECT boolean('t') AS true;
 
--- [SPARK-27931] Trim the string when cast string type to boolean type
 SELECT boolean('   f           ') AS `false`;
 
 SELECT boolean('true') AS true;
@@ -49,12 +48,10 @@ SELECT boolean('no') AS `false`;
 -- [SPARK-27923] PostgreSQL does not accept 'nay' but Spark SQL accepts it and sets it to NULL
 SELECT boolean('nay') AS error;
 
--- [SPARK-27931] Accept 'on' and 'off' as input for boolean data type
 SELECT boolean('on') AS true;
 
 SELECT boolean('off') AS `false`;
 
--- [SPARK-27931] Accept unique prefixes thereof
 SELECT boolean('of') AS `false`;
 
 -- [SPARK-27923] PostgreSQL does not accept 'o' but Spark SQL accepts it and sets it to NULL
@@ -101,7 +98,7 @@ SELECT boolean('f') <= boolean('t') AS true;
 
 -- explicit casts to/from text
 SELECT boolean(string('TrUe')) AS true, boolean(string('fAlse')) AS `false`;
--- [SPARK-27931] Trim the string when cast to boolean type
+
 SELECT boolean(string('    true   ')) AS true,
        boolean(string('     FALSE')) AS `false`;
 SELECT string(boolean(true)) AS true, string(boolean(false)) AS `false`;
diff --git a/sql/core/src/test/resources/sql-tests/results/pgSQL/boolean.sql.out b/sql/core/src/test/resources/sql-tests/results/pgSQL/boolean.sql.out
index c7903c8a34ef4..203806d43368a 100644
--- a/sql/core/src/test/resources/sql-tests/results/pgSQL/boolean.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/pgSQL/boolean.sql.out
@@ -39,7 +39,7 @@ SELECT boolean('   f           ') AS `false`
 -- !query 4 schema
 struct<false:boolean>
 -- !query 4 output
-NULL
+false
 
 
 -- !query 5
@@ -127,7 +127,7 @@ SELECT boolean('on') AS true
 -- !query 15 schema
 struct<true:boolean>
 -- !query 15 output
-NULL
+true
 
 
 -- !query 16
@@ -135,7 +135,7 @@ SELECT boolean('off') AS `false`
 -- !query 16 schema
 struct<false:boolean>
 -- !query 16 output
-NULL
+false
 
 
 -- !query 17
@@ -143,7 +143,7 @@ SELECT boolean('of') AS `false`
 -- !query 17 schema
 struct<false:boolean>
 -- !query 17 output
-NULL
+false
 
 
 -- !query 18
@@ -296,7 +296,7 @@ SELECT boolean(string('    true   ')) AS true,
 -- !query 36 schema
 struct<true:boolean,false:boolean>
 -- !query 36 output
-NULL	NULL
+true	false
 
 
 -- !query 37