IMPALA-14065: Support WHERE clause in SHOW PARTITIONS statement

This patch extends the SHOW PARTITIONS statement to allow an optional
WHERE clause that filters partitions based on partition column values.
The implementation adds support for various comparison operators,
IN lists, BETWEEN clauses, IS NULL, and logical AND/OR expressions
involving partition columns.

Non-partition columns, subqueries, and analytic expressions in the
WHERE clause are not allowed and will result in an analysis error.

New analyzer tests have been added to AnalyzeDDLTest#TestShowPartitions
to verify correct parsing, semantic validation, and error handling for
supported and unsupported cases.

Testing:
- Added new unit tests in AnalyzeDDLTest for valid and invalid WHERE
clause cases.
- Verified functional tests covering partition filtering behavior.

Change-Id: I2e2a14aabcea3fb17083d4ad6f87b7861113f89e
Reviewed-on: http://gerrit.cloudera.org:8080/23566
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>

tests/metadata/test_metadata_query_statements.py

@@ -20,6 +20,7 @@
 from __future__ import absolute_import, division, print_function
 import pytest
 import re
+import datetime
 
 from tests.common.impala_test_suite import ImpalaTestSuite
 from tests.common.skip import SkipIfFS, SkipIfCatalogV2
@@ -66,6 +67,44 @@ class TestMetadataQueryStatements(ImpalaTestSuite):
   def test_show_stats(self, vector):
     self.run_test_case('QueryTest/show-stats', vector, "functional")
 
+  def test_show_partitions_with_nondeterministic_functions(self):
+    """Test SHOW PARTITIONS WHERE with non-deterministic functions
+       like rand() and now().
+    """
+
+    # Test rand() - just verify the statement succeeds without errors
+    result = self.execute_query("show partitions functional.alltypes where rand() < 0.5")
+    assert result.success, "SHOW PARTITIONS with rand() should succeed"
+    # Verify we got some partitions back (rand() typically returns ~0.47 without seed)
+    assert len(result.data) > 0, "SHOW PARTITIONS with rand() should return some \
+        partitions"
+
+    # Test now() - verify the statement succeeds and returns partitions for current month
+    current_month = datetime.datetime.now().month
+    result = self.execute_query(
+        "show partitions functional.alltypes where month = month(now())")
+    assert result.success, "SHOW PARTITIONS with now() should succeed"
+
+    # Verify we got exactly the partitions for the current month
+    # alltypes has 2 years (2009, 2010) with all 12 months
+    # So we should get 2 partitions (one per year) for the current month
+    partition_months = []
+    for row in result.data:
+      # Skip the 'Total' row
+      if 'Total' not in row:
+        parts = row.split('\t')
+        if len(parts) >= 2:
+          partition_months.append(int(parts[1]))
+
+    # All returned partitions should be for the current month
+    for month in partition_months:
+      assert month == current_month, \
+          "Expected month {0}, got {1}".format(current_month, month)
+
+    # We should have 2 partitions (year=2009/month=N and year=2010/month=N)
+    assert len(partition_months) == 2, \
+        "Expected 2 partitions for current month, got {0}".format(len(partition_months))
+
   def test_describe_path(self, vector, unique_database):
     self.run_test_case('QueryTest/describe-path', vector, unique_database)