kangpinghuang commented on a change in pull request #243: Skip unnecessary
stream init and decrease the TCMalloc pressure (#242)
URL: https://github.com/apache/incubator-doris/pull/243#discussion_r225074663
##########
File path: be/src/olap/column_file/segment_reader.cpp
##########
@@ -775,6 +775,14 @@ OLAPStatus SegmentReader::_read_all_data_streams(size_t*
buffer_size) {
continue;
}
+ //skip unnecessary stream init
+ //if the query doesn't inclde this column, we needn't init the stream
for this column
+ //to reduce the call times for ByteBuffer::create and decrease the
TCMalloc pressure
+ if (!_is_column_included(unique_column_id)) {
+ *buffer_size += OLAP_DEFAULT_COLUMN_STREAM_BUFFER_SIZE +
sizeof(StreamHead);
+ continue;
+ }
+
Review comment:
it is done in line 768~771 and there is no need to add buffer_size if the
column is not included
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