HappenLee commented on code in PR #65482:
URL: https://github.com/apache/doris/pull/65482#discussion_r3581412282
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be/src/exec/operator/olap_scan_operator.cpp:
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@@ -698,14 +698,24 @@ Status
OlapScanLocalState::_init_scanners(std::list<ScannerSPtr>* scanners) {
bool read_row_binlog =
p._olap_scan_node.__isset.read_row_binlog &&
p._olap_scan_node.read_row_binlog;
bool has_tso_predicate = _scan_ranges[0]->__isset.start_tso ||
_scan_ranges[0]->__isset.end_tso;
+ // Query cache incremental merge: the read sources only cover the delta
+ // versions (cached_version, current_version], see prepare().
+ const bool cache_incremental =
+ _query_cache_decision != nullptr &&
+ _query_cache_decision->mode ==
QueryCacheInstanceDecision::Mode::INCREMENTAL;
+ const int64_t cache_start_version =
+ cache_incremental ? _query_cache_decision->cached_version + 1 : 0;
// The flag of preagg's meaning is whether return pre agg data(or partial
agg data)
// PreAgg ON: The storage layer returns partially aggregated data without
additional processing. (Fast data reading)
// for example, if a table is select userid,count(*) from base table.
// And the user send a query like select userid,count(*) from base table
group by userid.
// then the storage layer do not need do aggregation, it could just return
the partial agg data, because the compute layer will do aggregation.
// PreAgg OFF: The storage layer must complete pre-aggregation and return
fully aggregated data. (Slow data reading)
- if (enable_parallel_scan && !p._should_run_serial &&
+ // Incremental merge deltas are small by construction, so the parallel
Review Comment:
This piece of code is useless. Later, the line `auto delta_source =
_query_cache_decision->take_delta_read_source(_tablets[i].tablet->tablet_id())
` already ensures that the read version is correct. Instead, this code
introduces unnecessary complexity and should be removed.
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