[GitHub] [arrow-adbc] lidavidm commented on a diff in pull request #636: refactor(c/driver/postgresql): Factor out COPY reader and test it independently

["lidavidm (via GitHub)" <gi...@apache.org>]

lidavidm commented on code in PR #636:
URL: https://github.com/apache/arrow-adbc/pull/636#discussion_r1184899648


##########
c/driver/postgresql/statement.cc:
##########
@@ -797,9 +664,33 @@ AdbcStatusCode PostgresStatement::ExecuteQuery(struct ArrowArrayStream* stream,
       PQclear(result);
       return ADBC_STATUS_IO;
     }
-    AdbcStatusCode status = InferSchema(*type_resolver_, result, &reader_.schema_, error);
+
+    // Resolve the information from the PGresult into a PostgresType
+    PostgresType root_type;
+    AdbcStatusCode status =
+        ResolvePostgresType(*type_resolver_, result, &root_type, error);
     PQclear(result);
     if (status != ADBC_STATUS_OK) return status;
+
+    // Initialize the copy reader and infer the output schema (i.e., error for
+    // unsupported types before issuing the COPY query)
+    reader_.copy_reader_.reset(new PostgresCopyStreamReader());

Review Comment:
   Use make_unique?



##########
c/driver/postgresql/postgres_util.h:
##########
@@ -17,6 +17,8 @@
 
 #pragma once
 
+#include <string.h>

Review Comment:
   string.h -> cstring?



##########
c/driver/postgresql/statement.h:
##########
@@ -35,19 +37,24 @@ class PostgresStatement;
 /// \brief An ArrowArrayStream that reads tuples from a PGresult.
 class TupleReader final {
  public:
-  TupleReader(PGconn* conn) : conn_(conn), result_(nullptr), pgbuf_(nullptr) {
-    std::memset(&schema_, 0, sizeof(schema_));
+  TupleReader(PGconn* conn)
+      : conn_(conn),
+        result_(nullptr),
+        pgbuf_(nullptr),
+        copy_reader_(new PostgresCopyStreamReader()) {

Review Comment:
   Use make_unique over new?



##########
c/driver/postgresql/statement.h:
##########
@@ -35,19 +37,24 @@ class PostgresStatement;
 /// \brief An ArrowArrayStream that reads tuples from a PGresult.
 class TupleReader final {
  public:
-  TupleReader(PGconn* conn) : conn_(conn), result_(nullptr), pgbuf_(nullptr) {
-    std::memset(&schema_, 0, sizeof(schema_));
+  TupleReader(PGconn* conn)
+      : conn_(conn),
+        result_(nullptr),
+        pgbuf_(nullptr),
+        copy_reader_(new PostgresCopyStreamReader()) {

Review Comment:
   Or just leave it as nullptr if it's re-initialized again later.



##########
c/driver/postgresql/postgres_copy_reader_test.cc:
##########
@@ -0,0 +1,520 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <gtest/gtest.h>
+#include <nanoarrow/nanoarrow.h>
+
+#include "postgres_copy_reader.h"
+
+using adbcpq::PostgresCopyStreamReader;

Review Comment:
   You could just put the tests in the adbcpq namespace.



##########
c/driver/postgresql/postgres_copy_reader_test.cc:
##########
@@ -0,0 +1,520 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <gtest/gtest.h>
+#include <nanoarrow/nanoarrow.h>
+
+#include "postgres_copy_reader.h"
+
+using adbcpq::PostgresCopyStreamReader;
+using adbcpq::PostgresType;
+using adbcpq::PostgresTypeId;
+
+class PostgresCopyStreamTester {
+ public:
+  ArrowErrorCode Init(const PostgresType& root_type, ArrowError* error = nullptr) {
+    NANOARROW_RETURN_NOT_OK(reader_.Init(root_type));
+    NANOARROW_RETURN_NOT_OK(reader_.InferOutputSchema(error));
+    NANOARROW_RETURN_NOT_OK(reader_.InitFieldReaders(error));
+    return NANOARROW_OK;
+  }
+
+  ArrowErrorCode ReadAll(ArrowBufferView* data, ArrowError* error = nullptr) {
+    NANOARROW_RETURN_NOT_OK(reader_.ReadHeader(data, error));
+
+    int result;
+    do {
+      result = reader_.ReadRecord(data, error);
+    } while (result == NANOARROW_OK);
+
+    return result;
+  }
+
+  void GetSchema(ArrowSchema* out) { reader_.GetSchema(out); }
+
+  ArrowErrorCode GetArray(ArrowArray* out, ArrowError* error = nullptr) {
+    return reader_.GetArray(out, error);
+  }
+
+ private:
+  PostgresCopyStreamReader reader_;
+};
+
+// COPY (SELECT CAST("col" AS BOOLEAN) AS "col" FROM (  VALUES (TRUE), (FALSE), (NULL)) AS
+// drvd("col")) TO STDOUT;
+static uint8_t kTestPgCopyBoolean[] = {
+    0x50, 0x47, 0x43, 0x4f, 0x50, 0x59, 0x0a, 0xff, 0x0d, 0x0a, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x01, 0x00, 0x01,
+    0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+
+TEST(PostgresCopyUtilsTest, PostgresCopyReadBoolean) {
+  ArrowBufferView data;
+  data.data.as_uint8 = kTestPgCopyBoolean;
+  data.size_bytes = sizeof(kTestPgCopyBoolean);
+
+  auto col_type = PostgresType(PostgresTypeId::kBool);
+  PostgresType input_type(PostgresTypeId::kRecord);
+  input_type.AppendChild("col", col_type);
+
+  PostgresCopyStreamTester tester;
+  ASSERT_EQ(tester.Init(input_type), NANOARROW_OK);
+  ASSERT_EQ(tester.ReadAll(&data), ENODATA);
+
+  // Apparently the output above contains an extra 0xff 0xff at the end

Review Comment:
   Gonna guess it's this:
   
   > The file trailer consists of a 16-bit integer word containing -1. This is easily distinguished from a tuple's field-count word.
   
   https://www.postgresql.org/docs/current/sql-copy.html



##########
c/driver/postgresql/postgres_copy_reader_test.cc:
##########
@@ -0,0 +1,520 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <gtest/gtest.h>
+#include <nanoarrow/nanoarrow.h>
+
+#include "postgres_copy_reader.h"
+
+using adbcpq::PostgresCopyStreamReader;
+using adbcpq::PostgresType;
+using adbcpq::PostgresTypeId;
+
+class PostgresCopyStreamTester {
+ public:
+  ArrowErrorCode Init(const PostgresType& root_type, ArrowError* error = nullptr) {
+    NANOARROW_RETURN_NOT_OK(reader_.Init(root_type));
+    NANOARROW_RETURN_NOT_OK(reader_.InferOutputSchema(error));
+    NANOARROW_RETURN_NOT_OK(reader_.InitFieldReaders(error));
+    return NANOARROW_OK;
+  }
+
+  ArrowErrorCode ReadAll(ArrowBufferView* data, ArrowError* error = nullptr) {
+    NANOARROW_RETURN_NOT_OK(reader_.ReadHeader(data, error));
+
+    int result;
+    do {
+      result = reader_.ReadRecord(data, error);
+    } while (result == NANOARROW_OK);
+
+    return result;
+  }
+
+  void GetSchema(ArrowSchema* out) { reader_.GetSchema(out); }
+
+  ArrowErrorCode GetArray(ArrowArray* out, ArrowError* error = nullptr) {
+    return reader_.GetArray(out, error);
+  }
+
+ private:
+  PostgresCopyStreamReader reader_;
+};
+
+// COPY (SELECT CAST("col" AS BOOLEAN) AS "col" FROM (  VALUES (TRUE), (FALSE), (NULL)) AS
+// drvd("col")) TO STDOUT;
+static uint8_t kTestPgCopyBoolean[] = {
+    0x50, 0x47, 0x43, 0x4f, 0x50, 0x59, 0x0a, 0xff, 0x0d, 0x0a, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x01, 0x00, 0x01,
+    0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+
+TEST(PostgresCopyUtilsTest, PostgresCopyReadBoolean) {
+  ArrowBufferView data;
+  data.data.as_uint8 = kTestPgCopyBoolean;
+  data.size_bytes = sizeof(kTestPgCopyBoolean);
+
+  auto col_type = PostgresType(PostgresTypeId::kBool);
+  PostgresType input_type(PostgresTypeId::kRecord);
+  input_type.AppendChild("col", col_type);
+
+  PostgresCopyStreamTester tester;
+  ASSERT_EQ(tester.Init(input_type), NANOARROW_OK);
+  ASSERT_EQ(tester.ReadAll(&data), ENODATA);
+
+  // Apparently the output above contains an extra 0xff 0xff at the end
+  ASSERT_EQ(data.data.as_uint8 - kTestPgCopyBoolean, sizeof(kTestPgCopyBoolean));
+  ASSERT_EQ(data.size_bytes, 0);
+
+  struct ArrowArray array;
+  ASSERT_EQ(tester.GetArray(&array), NANOARROW_OK);
+  ASSERT_EQ(array.length, 3);
+  ASSERT_EQ(array.n_children, 1);
+
+  const uint8_t* validity =
+      reinterpret_cast<const uint8_t*>(array.children[0]->buffers[0]);
+  const uint8_t* data_buffer =
+      reinterpret_cast<const uint8_t*>(array.children[0]->buffers[1]);
+  ASSERT_NE(validity, nullptr);
+  ASSERT_NE(data_buffer, nullptr);
+
+  ASSERT_TRUE(ArrowBitGet(validity, 0));
+  ASSERT_TRUE(ArrowBitGet(validity, 1));
+  ASSERT_FALSE(ArrowBitGet(validity, 2));
+
+  ASSERT_TRUE(ArrowBitGet(data_buffer, 0));
+  ASSERT_FALSE(ArrowBitGet(data_buffer, 1));
+  ASSERT_FALSE(ArrowBitGet(data_buffer, 2));
+
+  array.release(&array);

Review Comment:
   nit, but it might be nice to use one of the RAII helpers to avoid leaking this if a test fails



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