feat(exasol): implement Table.nunique

Author: jcrist

ibis/backends/sql/compilers/exasol.py

@@ -189,9 +189,11 @@ def visit_CountStar(self, op, *, arg, where):
         return self.f.count(STAR)
 
     def visit_CountDistinctStar(self, op, *, arg, where):
-        raise com.UnsupportedOperationError(
-            "COUNT(DISTINCT *) is not supported in Exasol"
-        )
+        cols = [sg.column(k, quoted=self.quoted) for k in op.arg.schema.keys()]
+        if where is not None:
+            cols = [self.if_(where, c, NULL) for c in cols]
+        row = sge.Tuple(expressions=cols)
+        return self.f.count(sge.Distinct(expressions=[row]))
 
     def visit_Median(self, op, *, arg, where):
         return self.visit_Quantile(op, arg=arg, quantile=sge.convert(0.5), where=where)

ibis/backends/tests/test_aggregation.py

@@ -13,6 +13,7 @@
 from ibis import literal as L
 from ibis.backends.tests.errors import (
     ClickHouseDatabaseError,
+    ExaQueryError,
     GoogleBadRequest,
     ImpalaHiveServer2Error,
     MySQLNotSupportedError,
@@ -790,7 +791,6 @@ def test_arbitrary(backend, alltypes, df, filtered):
     raises=com.OperationNotDefinedError,
     reason="no one has attempted implementation yet",
 )
-@pytest.mark.notimpl(["exasol"], raises=com.UnsupportedOperationError)
 def test_count_distinct_star(alltypes, df, ibis_cond, pandas_cond):
     table = alltypes[["int_col", "double_col", "string_col"]]
     expr = table.nunique(where=ibis_cond(table))

ibis/backends/tests/test_generic.py

@@ -782,10 +782,7 @@ def test_table_info_large(con):
     reason="quantile and mode is not supported",
 )
 @pytest.mark.notimpl(
-    [
-        "exasol",
-        "druid",
-    ],
+    ["druid"],
     raises=com.OperationNotDefinedError,
     reason="Mode and StandardDev is not supported",
 )
@@ -829,10 +826,10 @@ def test_table_info_large(con):
                 pytest.mark.notimpl(
                     [
                         "clickhouse",
+                        "exasol",
+                        "impala",
                         "pyspark",
-                        "clickhouse",
                         "risingwave",
-                        "impala",
                     ],
                     raises=com.OperationNotDefinedError,
                     reason="mode is not supported",
@@ -911,10 +908,10 @@ def test_table_info_large(con):
                 pytest.mark.notimpl(
                     [
                         "clickhouse",
+                        "exasol",
+                        "impala",
                         "pyspark",
-                        "clickhouse",
                         "risingwave",
-                        "impala",
                     ],
                     raises=com.OperationNotDefinedError,
                     reason="mode is not supported",
@@ -958,10 +955,7 @@ def test_table_describe(alltypes, selector, expected_columns):
     reason="quantile is not supported",
 )
 @pytest.mark.notimpl(
-    [
-        "exasol",
-        "druid",
-    ],
+    ["druid"],
     raises=com.OperationNotDefinedError,
     reason="StandardDev is not supported",
 )