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Showcase dereference pushdown limited effectiveness in Iceberg #17145

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Apr 24, 2023
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Showcase dereference pushdown limited effectiveness in Iceberg #17145

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7 changes: 6 additions & 1 deletion plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/BaseIcebergConnectorTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4941,11 +4941,16 @@ public void testProjectionPushdownReadsLessData()
getSession(),
selectQuery,
statsWithPushdown -> {
DataSize physicalDataSizeWithPushdown = statsWithPushdown.getPhysicalInputDataSize();
DataSize processedDataSizeWithPushdown = statsWithPushdown.getProcessedInputDataSize();
assertQueryStats(
sessionWithoutPushdown,
selectQuery,
statsWithoutPushdown -> assertThat(statsWithoutPushdown.getProcessedInputDataSize()).isGreaterThan(processedDataSizeWithPushdown),
statsWithoutPushdown -> {
//TODO (https://github.com/trinodb/trino/issues/17156) add dereference pushdown on the physical layer
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We may need more test data to show data pruning happens on read and/or disable Parquet compression (on write).
3000 'Z' characters will compress very well, and the coalescing adjacent reads should kick in

assertThat(statsWithoutPushdown.getPhysicalInputDataSize()).isEqualTo(physicalDataSizeWithPushdown);
assertThat(statsWithoutPushdown.getProcessedInputDataSize()).isGreaterThan(processedDataSizeWithPushdown);
},
results -> assertEquals(results.getOnlyColumnAsSet(), expected));
},
results -> assertEquals(results.getOnlyColumnAsSet(), expected));
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