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Avoid extra allocation in OrderByOperator#getOutput() #16447

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Merged
martint merged 1 commit into from
Mar 17, 2023
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Avoid extra allocation in OrderByOperator#getOutput() #16447

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7 changes: 1 addition & 6 deletions core/trino-main/src/main/java/io/trino/operator/OrderByOperator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
import com.google.common.util.concurrent.ListenableFuture;
import io.trino.memory.context.LocalMemoryContext;
import io.trino.spi.Page;
import io.trino.spi.block.Block;
import io.trino.spi.connector.SortOrder;
import io.trino.spi.type.Type;
import io.trino.spiller.Spiller;
Expand Down Expand Up @@ -286,11 +285,7 @@ public Page getOutput()
return null;
}
Page nextPage = next.get();
Block[] blocks = new Block[outputChannels.length];
for (int i = 0; i < outputChannels.length; i++) {
blocks[i] = nextPage.getBlock(outputChannels[i]);
}
return new Page(nextPage.getPositionCount(), blocks);
return nextPage.getColumns(outputChannels);
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@martint martint Mar 8, 2023

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getColumns() calls wrapBlocksWithoutCopy(positionCount, blocks), while new Page(count, blocks) uses blocksCopyRequired = true. Have you analyzed the impact of that change in semantics?

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@pettyjamesm pettyjamesm Mar 8, 2023

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Yep, that's the intention behind this change. The Block[] array in the previous implementation was created locally (not shared anywhere else) but was created once and then immediately cloned by the page constructor unnecessarily. Now we only create a single copy of the blocks array inside of Page#getColumns which requires no additional copy (and makes the code a little cleaner).

}

@Override
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