[GitHub] [arrow-adbc] lidavidm commented on a diff in pull request #683: refactor(c/driver/postgresql): Implement InputIterator for ResultHelper

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

lidavidm commented on code in PR #683:
URL: https://github.com/apache/arrow-adbc/pull/683#discussion_r1195072804


##########
c/driver/postgresql/connection.cc:
##########
@@ -170,13 +241,10 @@ AdbcStatusCode PostgresConnectionGetObjectsImpl(
 
     PqResultHelper result_helper = PqResultHelper{conn, query.buffer};
     StringBuilderReset(&query);
-    pg_result* result = result_helper.Execute();
 
-    ExecStatusType pq_status = PQresultStatus(result);
-    if (pq_status == PGRES_TUPLES_OK) {
-      int num_rows = PQntuples(result);
-      for (int row = 0; row < num_rows; row++) {
-        const char* db_name = PQgetvalue(result, row, 0);
+    if (result_helper.Status() == PGRES_TUPLES_OK) {

Review Comment:
   Hmm, I suppose the original code had the same issue, but we should be returning an error if the status here is not OK.



##########
c/driver/postgresql/connection.cc:
##########
@@ -260,39 +328,39 @@ AdbcStatusCode PostgresConnection::GetTableSchema(const char* catalog,
 
   PqResultHelper result_helper = PqResultHelper{conn_, query.buffer};
   StringBuilderReset(&query);
-  pg_result* result = result_helper.Execute();
-
-  ExecStatusType pq_status = PQresultStatus(result);
-  auto uschema = nanoarrow::UniqueSchema();
 
-  if (pq_status == PGRES_TUPLES_OK) {
-    int num_rows = PQntuples(result);
+  if (result_helper.Status() != PGRES_TUPLES_OK) {
+    SetError(error, "%s%s", "Failed to get table schema: ", PQerrorMessage(conn_));
+    final_status = ADBC_STATUS_IO;
+  } else {
+    auto uschema = nanoarrow::UniqueSchema();
     ArrowSchemaInit(uschema.get());
-    CHECK_NA(INTERNAL, ArrowSchemaSetTypeStruct(uschema.get(), num_rows), error);
+    CHECK_NA(INTERNAL, ArrowSchemaSetTypeStruct(uschema.get(), result_helper.NumRows()),
+             error);
 
     ArrowError na_error;
-    for (int row = 0; row < num_rows; row++) {
-      const char* colname = PQgetvalue(result, row, 0);
+    int row_counter = 0;
+    for (auto row : result_helper) {
+      const char* colname = row[0].data;
       const Oid pg_oid = static_cast<uint32_t>(
-          std::strtol(PQgetvalue(result, row, 1), /*str_end=*/nullptr, /*base=*/10));
+          std::strtol(row[1].data, /*str_end=*/nullptr, /*base=*/10));
 
       PostgresType pg_type;
       if (type_resolver_->Find(pg_oid, &pg_type, &na_error) != NANOARROW_OK) {
-        SetError(error, "%s%d%s%s%s%" PRIu32, "Column #", row + 1, " (\"", colname,
-                 "\") has unknown type code ", pg_oid);
+        SetError(error, "%s%d%s%s%s%" PRIu32, "Column #", row_counter + 1, " (\"",

Review Comment:
   Hmm, `Column #` but row_counter? (again this was also in the original code but I just noticed it)



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