diff --git a/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/spi/ScalarFunction.java b/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/spi/ScalarFunction.java
index 6b6f27440a470..6fbacfa86e8b9 100644
--- a/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/spi/ScalarFunction.java
+++ b/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/spi/ScalarFunction.java
@@ -38,6 +38,10 @@ public enum ScalarFunction {
     LESS_THAN_OR_EQUAL(Category.COMPARISON, SqlKind.LESS_THAN_OR_EQUAL),
     IS_NULL(Category.COMPARISON, SqlKind.IS_NULL),
     IS_NOT_NULL(Category.COMPARISON, SqlKind.IS_NOT_NULL),
+    IS_TRUE(Category.COMPARISON, SqlKind.IS_TRUE),
+    IS_FALSE(Category.COMPARISON, SqlKind.IS_FALSE),
+    IS_NOT_TRUE(Category.COMPARISON, SqlKind.IS_NOT_TRUE),
+    IS_NOT_FALSE(Category.COMPARISON, SqlKind.IS_NOT_FALSE),
     IN(Category.COMPARISON, SqlKind.IN),
     LIKE(Category.COMPARISON, SqlKind.LIKE),
     PREFIX(Category.COMPARISON, SqlKind.OTHER_FUNCTION),
diff --git a/sandbox/plugins/analytics-backend-datafusion/src/main/java/org/opensearch/be/datafusion/DataFusionAnalyticsBackendPlugin.java b/sandbox/plugins/analytics-backend-datafusion/src/main/java/org/opensearch/be/datafusion/DataFusionAnalyticsBackendPlugin.java
index b2df66c2526d8..8dff5eb1bb331 100644
--- a/sandbox/plugins/analytics-backend-datafusion/src/main/java/org/opensearch/be/datafusion/DataFusionAnalyticsBackendPlugin.java
+++ b/sandbox/plugins/analytics-backend-datafusion/src/main/java/org/opensearch/be/datafusion/DataFusionAnalyticsBackendPlugin.java
@@ -101,6 +101,10 @@ public class DataFusionAnalyticsBackendPlugin implements AnalyticsSearchBackendP
         ScalarFunction.LESS_THAN_OR_EQUAL,
         ScalarFunction.IS_NULL,
         ScalarFunction.IS_NOT_NULL,
+        ScalarFunction.IS_TRUE,
+        ScalarFunction.IS_FALSE,
+        ScalarFunction.IS_NOT_TRUE,
+        ScalarFunction.IS_NOT_FALSE,
         ScalarFunction.IN,
         ScalarFunction.LIKE,
         ScalarFunction.REGEXP_CONTAINS,
@@ -146,6 +150,10 @@ public class DataFusionAnalyticsBackendPlugin implements AnalyticsSearchBackendP
         ScalarFunction.IS_NULL,
         ScalarFunction.IS_NOT_NULL,
         ScalarFunction.NULLIF,
+        ScalarFunction.IS_TRUE,
+        ScalarFunction.IS_FALSE,
+        ScalarFunction.IS_NOT_TRUE,
+        ScalarFunction.IS_NOT_FALSE,
         // ABS / SUBSTRING — PPL sort-pushdown moves these into the project tree; DataFusion has
         // both natively and isthmus's default catalog binds them, so no adapter needed.
         ScalarFunction.ABS,
diff --git a/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q19.ppl b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q19.ppl
new file mode 100644
index 0000000000000..6ec9a7a8eb1f0
--- /dev/null
+++ b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q19.ppl
@@ -0,0 +1 @@
+source=function_tests | where not true = case(amount > 0, true, amount < 0, false else false) | fields user, amount, status | head 10
diff --git a/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q20.ppl b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q20.ppl
new file mode 100644
index 0000000000000..47089ef801a3e
--- /dev/null
+++ b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q20.ppl
@@ -0,0 +1 @@
+source=function_tests | where true = case(amount > 0, true else false) | fields user, amount | head 10
diff --git a/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q21.ppl b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q21.ppl
new file mode 100644
index 0000000000000..c3f6843cd849d
--- /dev/null
+++ b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q21.ppl
@@ -0,0 +1 @@
+source=function_tests | where false = case(amount > 0, true else false) | fields user, amount | head 10
diff --git a/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q22.ppl b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q22.ppl
new file mode 100644
index 0000000000000..dd18eaceb1247
--- /dev/null
+++ b/sandbox/qa/analytics-engine-rest/src/test/resources/datasets/functions/ppl/q22.ppl
@@ -0,0 +1 @@
+source=function_tests | eval is_positive = case(amount > 0, true else false) | where not false = is_positive | fields user, amount, is_positive | head 10