From 5637d8fecd58b8c0f42775a6ac16b37e9452b0e1 Mon Sep 17 00:00:00 2001
From: Jim Crist-Harif <jcristharif@gmail.com>
Date: Mon, 19 Aug 2024 15:29:45 -0500
Subject: [PATCH] feat(exasol): implement `cov`/`corr`

---
 ibis/backends/sql/compilers/exasol.py   | 15 ++++++++++++++-
 ibis/backends/tests/test_aggregation.py |  4 ++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/ibis/backends/sql/compilers/exasol.py b/ibis/backends/sql/compilers/exasol.py
index 21a9e1ce0d0c7..8b3bd7fb713c8 100644
--- a/ibis/backends/sql/compilers/exasol.py
+++ b/ibis/backends/sql/compilers/exasol.py
@@ -44,7 +44,6 @@ class ExasolCompiler(SQLGlotCompiler):
         ops.ArrayUnion,
         ops.ArrayZip,
         ops.BitwiseNot,
-        ops.Covariance,
         ops.CumeDist,
         ops.DateAdd,
         ops.DateSub,
@@ -120,6 +119,20 @@ def visit_NonNullLiteral(self, op, *, value, dtype):
     def visit_Date(self, op, *, arg):
         return self.cast(arg, dt.date)
 
+    def visit_Correlation(self, op, *, left, right, how, where):
+        if how == "sample":
+            raise com.UnsupportedOperationError(
+                "Exasol only implements `pop` correlation coefficient"
+            )
+
+        if (left_type := op.left.dtype).is_boolean():
+            left = self.cast(left, dt.Int32(nullable=left_type.nullable))
+
+        if (right_type := op.right.dtype).is_boolean():
+            right = self.cast(right, dt.Int32(nullable=right_type.nullable))
+
+        return self.agg.corr(left, right, where=where)
+
     def visit_GroupConcat(self, op, *, arg, sep, where, order_by):
         if where is not None:
             arg = self.if_(where, arg, NULL)
diff --git a/ibis/backends/tests/test_aggregation.py b/ibis/backends/tests/test_aggregation.py
index 40e2a5ca2501e..cdaa72d5fb6e1 100644
--- a/ibis/backends/tests/test_aggregation.py
+++ b/ibis/backends/tests/test_aggregation.py
@@ -1013,7 +1013,7 @@ def test_quantile(
                     raises=com.OperationNotDefinedError,
                 ),
                 pytest.mark.notyet(
-                    ["postgres", "duckdb", "snowflake", "risingwave"],
+                    ["postgres", "duckdb", "snowflake", "risingwave", "exasol"],
                     raises=com.UnsupportedOperationError,
                     reason="backend only implements population correlation coefficient",
                 ),
@@ -1114,7 +1114,7 @@ def test_quantile(
         ),
     ],
 )
-@pytest.mark.notimpl(["mssql", "exasol"], raises=com.OperationNotDefinedError)
+@pytest.mark.notimpl(["mssql"], raises=com.OperationNotDefinedError)
 def test_corr_cov(
     con,
     batting,