Backport #42198 to 22.8: Fix a bug with projections and the `aggregat…

…e_functions_null_for_empty` setting

src/Storages/MergeTree/MergeTreeData.cpp

@@ -5504,7 +5504,8 @@ std::optional<ProjectionCandidate> MergeTreeData::getQueryProcessingStageWithAgg
 {
     const auto & metadata_snapshot = storage_snapshot->metadata;
     const auto & settings = query_context->getSettingsRef();
-    if (!settings.allow_experimental_projection_optimization || query_info.ignore_projections || query_info.is_projection_query)
+    if (!settings.allow_experimental_projection_optimization || query_info.ignore_projections || query_info.is_projection_query
+        || settings.aggregate_functions_null_for_empty /* projections don't work correctly with this setting */)
         return std::nullopt;
 
     // Currently projections don't support parallel replicas reading yet.

tests/queries/0_stateless/02460_projections_and_aggregate_null_if_empty.reference

@@ -0,0 +1 @@
+20220920

tests/queries/0_stateless/02460_projections_and_aggregate_null_if_empty.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+# Tags: no-fasttest
+# Tag no-fasttest: depends on bzip2
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+${CLICKHOUSE_LOCAL} --aggregate_functions_null_for_empty=1 --multiquery --query "create table test_date (date Int32) ENGINE = MergeTree ORDER BY (date) as select 20220920; SELECT max(date) FROM test_date";