[GitHub] [doris] BePPPower commented on a diff in pull request #13515: [fix](csv-reader) fix bug that csv reader can not read text format hms table

[GitBox <gi...@apache.org>]

BePPPower commented on code in PR #13515:
URL: https://github.com/apache/doris/pull/13515#discussion_r1000829421


##########
be/src/vec/exec/format/csv/csv_reader.cpp:
##########
@@ -150,16 +175,15 @@ Status CsvReader::get_next_block(Block* block, size_t* read_rows, bool* eof) {
             continue;
         }
 
-        // TODO(ftw): check read_rows?
-        ++(*read_rows);
-        RETURN_IF_ERROR(_fill_dest_columns(Slice(ptr, size), columns));
+        RETURN_IF_ERROR(_fill_dest_columns(Slice(ptr, size), block));
+        ++rows;
 
         if (_line_reader_eof == true) {
             *eof = true;
             break;
         }

Review Comment:
   I think this judgment is redundant and it is wasting time if we judge it every time in the `while` loop.
   ```suggestion
   ```



##########
be/src/vec/exec/format/csv/csv_reader.cpp:
##########
@@ -134,10 +150,19 @@ Status CsvReader::get_next_block(Block* block, size_t* read_rows, bool* eof) {
         return Status::OK();
     }
 
-    const int batch_size = _state->batch_size();
-    auto columns = block->mutate_columns();
+    if (!_init_column_pos) {
+        // Save mapping from file slot desc to column in block, so that we don't need to
+        // find column in block by name every time.
+        for (int i = 0; i < _file_slot_descs.size(); ++i) {
+            size_t position = block->get_position_by_name(_file_slot_descs[i]->col_name());
+            _col_posistions.push_back(position);
+        }
+        _init_column_pos = true;
+    }
 
-    while (columns[0]->size() < batch_size && !_line_reader_eof) {
+    const int batch_size = _state->batch_size();
+    int rows = 0;
+    while (rows < batch_size && !_line_reader_eof) {

Review Comment:
   `_fill_dest_columns` may filter invalid line and `block` does not actually add a new line. But `++rows` may make the `while(row < bactch_size)` exit in advance.



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