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Avoid reading Iceberg column stats when they are not needed #14504

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Merged
findepi merged 1 commit into from
Oct 13, 2022
Merged

Avoid reading Iceberg column stats when they are not needed #14504

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3 changes: 1 addition & 2 deletions plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java
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Original file line number Diff line number Diff line change
Expand Up @@ -484,8 +484,7 @@ public ConnectorTableProperties getTableProperties(ConnectorSession session, Con
Supplier<List<FileScanTask>> lazyFiles = Suppliers.memoize(() -> {
TableScan tableScan = icebergTable.newScan()
.useSnapshot(table.getSnapshotId().get())
.filter(toIcebergExpression(enforcedPredicate))
.includeColumnStats();
.filter(toIcebergExpression(enforcedPredicate));

try (CloseableIterable<FileScanTask> iterator = tableScan.planFiles()) {
return ImmutableList.copyOf(iterator);
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16 changes: 10 additions & 6 deletions plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergSplitSource.java
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Expand Up @@ -163,12 +163,14 @@ public CompletableFuture<ConnectorSplitBatch> getNextBatch(int maxSize)

if (fileScanTaskIterable == null) {
// Used to avoid duplicating work if the Dynamic Filter was already pushed down to the Iceberg API
boolean dynamicFilterIsComplete = dynamicFilter.isComplete();
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@alexjo2144 alexjo2144 Oct 6, 2022

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@raunaqmorarka can you sanity check for me that isComplete() means that the filter we get from getCurrentPredicate() will not change later in the query?

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@raunaqmorarka raunaqmorarka Oct 7, 2022

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yes, that is right

this.pushedDownDynamicFilterPredicate = dynamicFilter.getCurrentPredicate().transformKeys(IcebergColumnHandle.class::cast);
TupleDomain<IcebergColumnHandle> fullPredicate = tableHandle.getUnenforcedPredicate()
.intersect(pushedDownDynamicFilterPredicate);
// TODO: (https://github.com/trinodb/trino/issues/9743): Consider removing TupleDomain#simplify
TupleDomain<IcebergColumnHandle> simplifiedPredicate = fullPredicate.simplify(ICEBERG_DOMAIN_COMPACTION_THRESHOLD);
if (!simplifiedPredicate.equals(fullPredicate)) {
boolean usedSimplifiedPredicate = !simplifiedPredicate.equals(fullPredicate);
if (usedSimplifiedPredicate) {
// Pushed down predicate was simplified, always evaluate it against individual splits
this.pushedDownDynamicFilterPredicate = TupleDomain.all();
}
Expand All @@ -182,11 +184,13 @@ public CompletableFuture<ConnectorSplitBatch> getNextBatch(int maxSize)
}

Expression filterExpression = toIcebergExpression(effectivePredicate);
this.fileScanTaskIterable = TableScanUtil.splitFiles(
tableScan.filter(filterExpression)
.includeColumnStats()
.planFiles(),
tableScan.targetSplitSize());
// If the Dynamic Filter will be evaluated against each file, stats are required. Otherwise, skip them.
boolean requiresColumnStats = usedSimplifiedPredicate || !dynamicFilterIsComplete;
TableScan scan = tableScan.filter(filterExpression);
if (requiresColumnStats) {
scan = scan.includeColumnStats();
}
this.fileScanTaskIterable = TableScanUtil.splitFiles(scan.planFiles(), tableScan.targetSplitSize());
closer.register(fileScanTaskIterable);
this.fileScanTaskIterator = fileScanTaskIterable.iterator();
closer.register(fileScanTaskIterator);
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