[SNOW-1739096] Disallow detecting none select statement as repeated s…

…ubquery (#2467)

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SNOW-1739096

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- [x] I am adding a new automated test(s) to verify correctness of my
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3. Please describe how your code solves the related issue.

Repeated subquery elimination is only designed to eliminate subquery
that is selectStatement. Since we do not distinguish query that is
selectStatement and none selectStatement, we can incorrectly detect non
selectstatement as candidate. for example, when we have
```
  df1 = session.sql("show tables")
   df2 = session.sql("show tables")

   df_result = df1.union(df2)
```
The show table query its-self can be incorrectly detected as a common
query and produced wrong query like
```
with_cte_xxx (show tables) xxxx
```

In this pr, we exclude none-selectstatment from the candidate node
encoding to avoid count those node as candidate for repeated subquery
elimination

src/snowflake/snowpark/_internal/analyzer/cte_utils.py

@@ -14,6 +14,7 @@
 )
 from snowflake.snowpark._internal.utils import (
     TempObjectType,
+    is_sql_select_statement,
     random_name_for_temp_object,
 )
 
@@ -186,6 +187,12 @@ def encoded_query_id(node) -> Optional[str]:
         query = node.sql_query
         query_params = node.query_params
 
+    if not is_sql_select_statement(query):
+        # common subquery elimination only supports eliminating
+        # subquery that is select statement. Skip encoding the query
+        # to avoid being detected as a common subquery.
+        return None
+
     string = f"{query}#{query_params}" if query_params else query
     try:
         return hashlib.sha256(string.encode()).hexdigest()[:10]

tests/integ/test_cte.py

@@ -747,6 +747,25 @@ def test_sql(session, query):
         assert count_number_of_ctes(df_result.queries["queries"][-1]) == 1
 
 
+def test_sql_non_select(session):
+    df1 = session.sql("show tables in schema limit 10")
+    df2 = session.sql("show tables in schema limit 10")
+
+    df_result = df1.union(df2).select('"name"').filter(lit(True))
+
+    check_result(
+        session,
+        df_result,
+        # since the two show tables are called in two different dataframe, we
+        # won't be able to detect those as common subquery.
+        expect_cte_optimized=False,
+        query_count=3,
+        describe_count=0,
+        union_count=1,
+        join_count=0,
+    )
+
+
 @pytest.mark.parametrize(
     "action",
     [