eldenmoon commented on code in PR #18654:
URL: https://github.com/apache/doris/pull/18654#discussion_r1191856283
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fe/fe-core/src/main/java/org/apache/doris/nereids/glue/translator/PhysicalPlanTranslator.java:
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@@ -195,6 +197,45 @@ public PhysicalPlanTranslator(PlanTranslatorContext
context, StatsErrorEstimator
this.statsErrorEstimator = statsErrorEstimator;
}
+ // We use two phase read to optimize sql like: select * from tbl [where
xxx = ???] [order by column1] [limit n]
+ // in the first phase, we add an extra column `RowId` to Block, and sort
blocks in TopN nodes
+ // in the second phase, we have n rows, we do a fetch rpc to get all
rowids data for the n rows
+ // and reconconstruct the final block
+ private void setResultSinkFetchOptionIfNeed() {
+ boolean needFetch = false;
+ // Only single olap table should be fetched
+ OlapTable fetchOlapTable = null;
+ for (PlanFragment fragment : context.getPlanFragments()) {
Review Comment:
sortNode.getUseTwoPhaseReadOpt() flag makes sure the query is simple enough
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