fix(cubestore): Mark nullable fields for system.cache/queue/queue_results (#6984)

Author: ovr

rust/cubestore/cubestore/src/queryplanner/info_schema/system_cache.rs

@@ -24,11 +24,11 @@ impl InfoSchemaTableDef for SystemCacheTableDef {
     fn schema(&self) -> Vec<Field> {
         vec![
             Field::new("id", DataType::Utf8, false),
-            Field::new("prefix", DataType::Utf8, false),
+            Field::new("prefix", DataType::Utf8, true),
             Field::new(
                 "expire",
                 DataType::Timestamp(TimeUnit::Nanosecond, None),
-                false,
+                true,
             ),
             Field::new("value", DataType::Utf8, false),
         ]

rust/cubestore/cubestore/src/queryplanner/info_schema/system_queue.rs

@@ -24,7 +24,7 @@ impl InfoSchemaTableDef for SystemQueueTableDef {
     fn schema(&self) -> Vec<Field> {
         vec![
             Field::new("id", DataType::Utf8, false),
-            Field::new("prefix", DataType::Utf8, false),
+            Field::new("prefix", DataType::Utf8, true),
             Field::new(
                 "created",
                 DataType::Timestamp(TimeUnit::Nanosecond, None),

rust/cubestore/cubestore/src/queryplanner/info_schema/system_queue_results.rs

@@ -66,7 +66,7 @@ impl InfoSchemaTableDef for SystemQueueResultsTableDef {
                 Arc::new(StringArray::from(
                     items
                         .iter()
-                        .map(|row| format!("{:?}", row.get_row().get_value()))
+                        .map(|row| row.get_row().get_value().clone())
                         .collect::<Vec<_>>(),
                 ))
             }),