feat(arrow): add read_replica_type resource attribute column

src/config/guc.c

@@ -373,7 +373,7 @@ void PschInitGuc(void) {
       "pg_stat_ch.extra_attributes",
       "Key-value pairs appended to exported Arrow batches.",
       "Semicolon-separated k:v pairs for resource columns: "
-      "'instance_ubid:abc;server_role:primary;region:us-east-1'.",
+      "'instance_ubid:abc;server_role:primary;read_replica_type:regional;region:us-east-1'.",
       &psch_extra_attributes,
       "",
       PGC_SIGHUP,

src/export/arrow_batch.cc

@@ -193,6 +193,7 @@ struct ArrowBatchBuilder::Impl {
   arrow::StringBuilder instance_ubid_builder;
   arrow::StringBuilder server_ubid_builder;
   DictBuilder server_role_builder;
+  DictBuilder read_replica_type_builder;
   DictBuilder region_builder;
   DictBuilder cell_builder;
   DictBuilder service_version_builder;
@@ -260,6 +261,7 @@ struct ArrowBatchBuilder::Impl {
         arrow::field("instance_ubid", arrow::utf8()),
         arrow::field("server_ubid", arrow::utf8()),
         arrow::field("server_role", DictionaryUtf8Type()),
+        arrow::field("read_replica_type", DictionaryUtf8Type()),
         arrow::field("region", DictionaryUtf8Type()),
         arrow::field("cell", DictionaryUtf8Type()),
         arrow::field("service_version", DictionaryUtf8Type()),
@@ -424,6 +426,8 @@ struct ArrowBatchBuilder::Impl {
                       "Arrow instance_ubid append") ||
         !AppendString(&server_ubid_builder, ExtraAttr("server_ubid"), "Arrow server_ubid append") ||
         !AppendString(&server_role_builder, ExtraAttr("server_role"), "Arrow server_role append") ||
+        !AppendString(&read_replica_type_builder, ExtraAttr("read_replica_type"),
+                      "Arrow read_replica_type append") ||
         !AppendString(&region_builder, ExtraAttr("region"), "Arrow region append") ||
         !AppendString(&cell_builder, ExtraAttr("cell"), "Arrow cell append") ||
         !AppendString(&service_version_builder, service_version, "Arrow service_version append") ||
@@ -432,12 +436,13 @@ struct ArrowBatchBuilder::Impl {
       return false;
     }
 
-    estimated_bytes +=
-        kFixedBytesPerRow + db_name.size() + db_user.size() + app.size() + client_addr.size() +
-        query_text.size() + err_message.size() + err_sqlstate.size() + service_version.size() +
-        ExtraAttr("instance_ubid").size() + ExtraAttr("server_ubid").size() +
-        ExtraAttr("server_role").size() + ExtraAttr("region").size() + ExtraAttr("cell").size() +
-        ExtraAttr("host_id").size() + ExtraAttr("pod_name").size();
+    estimated_bytes += kFixedBytesPerRow + db_name.size() + db_user.size() + app.size() +
+                       client_addr.size() + query_text.size() + err_message.size() +
+                       err_sqlstate.size() + service_version.size() +
+                       ExtraAttr("instance_ubid").size() + ExtraAttr("server_ubid").size() +
+                       ExtraAttr("server_role").size() + ExtraAttr("read_replica_type").size() +
+                       ExtraAttr("region").size() + ExtraAttr("cell").size() +
+                       ExtraAttr("host_id").size() + ExtraAttr("pod_name").size();
     ++num_rows;
     return true;
   }
@@ -519,6 +524,7 @@ struct ArrowBatchBuilder::Impl {
         !add_array(&instance_ubid_builder, "Arrow instance_ubid finish") ||
         !add_array(&server_ubid_builder, "Arrow server_ubid finish") ||
         !add_dict_array(&server_role_builder, "Arrow server_role finish") ||
+        !add_dict_array(&read_replica_type_builder, "Arrow read_replica_type finish") ||
         !add_dict_array(&region_builder, "Arrow region finish") ||
         !add_dict_array(&cell_builder, "Arrow cell finish") ||
         !add_dict_array(&service_version_builder, "Arrow service_version finish") ||
@@ -625,6 +631,7 @@ struct ArrowBatchBuilder::Impl {
     instance_ubid_builder.Reset();
     server_ubid_builder.Reset();
     server_role_builder.ResetFull();
+    read_replica_type_builder.ResetFull();
     region_builder.ResetFull();
     cell_builder.ResetFull();
     service_version_builder.ResetFull();

t/026_arrow_dump.pl

@@ -186,7 +186,7 @@
     'duration_us', 'rows', 'pid', 'query_id',
     'shared_blks_hit', 'shared_blks_read',
     'wal_records', 'wal_bytes',
-    'service_version', 'region',
+    'service_version', 'region', 'read_replica_type',
 ]
 missing = [c for c in expected if schema.get_field_index(c) == -1]
 if missing:
@@ -203,6 +203,11 @@
 rows_field = schema.field('rows')
 assert rows_field.type == pa.uint64(), f"rows type wrong: {rows_field.type}"
 
+# read_replica_type is a dictionary-encoded column (like server_role/region), not plain utf8.
+rr_field = schema.field('read_replica_type')
+assert pa.types.is_dictionary(rr_field.type), f"read_replica_type not dict-encoded: {rr_field.type}"
+assert rr_field.type.value_type == pa.utf8(), f"read_replica_type dict value type wrong: {rr_field.type.value_type}"
+
 print(f"OK:fields={len(schema)},rows={total_rows}")
 PYEOF