Examples with TopNMetricSpec org.apache.druid.query.topn.TopNMetricSpec used on opensource projects

Example 1 with TopNMetricSpec

use of org.apache.druid.query.topn.TopNMetricSpec in project druid by druid-io.

the class DruidQuery method toTopNQuery.

/**
 * Return this query as a TopN query, or null if this query is not compatible with TopN.
 *
 * @return query or null
 */
@Nullable
private TopNQuery toTopNQuery(final QueryFeatureInspector queryFeatureInspector) {
    // Must be allowed by the QueryMaker.
    if (!queryFeatureInspector.feature(QueryFeature.CAN_RUN_TOPN)) {
        return null;
    }
    // Must have GROUP BY one column, no GROUPING SETS, ORDER BY ≤ 1 column, LIMIT > 0 and ≤ maxTopNLimit,
    // no OFFSET, no HAVING.
    final boolean topNOk = grouping != null && grouping.getDimensions().size() == 1 && !grouping.getSubtotals().hasEffect(grouping.getDimensionSpecs()) && sorting != null && (sorting.getOrderBys().size() <= 1 && sorting.getOffsetLimit().hasLimit() && sorting.getOffsetLimit().getLimit() > 0 && sorting.getOffsetLimit().getLimit() <= plannerContext.getPlannerConfig().getMaxTopNLimit() && !sorting.getOffsetLimit().hasOffset()) && grouping.getHavingFilter() == null;
    if (!topNOk) {
        return null;
    }
    final DimensionSpec dimensionSpec = Iterables.getOnlyElement(grouping.getDimensions()).toDimensionSpec();
    // grouping col cannot be type array
    if (dimensionSpec.getOutputType().isArray()) {
        return null;
    }
    final OrderByColumnSpec limitColumn;
    if (sorting.getOrderBys().isEmpty()) {
        limitColumn = new OrderByColumnSpec(dimensionSpec.getOutputName(), OrderByColumnSpec.Direction.ASCENDING, Calcites.getStringComparatorForValueType(dimensionSpec.getOutputType()));
    } else {
        limitColumn = Iterables.getOnlyElement(sorting.getOrderBys());
    }
    final TopNMetricSpec topNMetricSpec;
    if (limitColumn.getDimension().equals(dimensionSpec.getOutputName())) {
        // DimensionTopNMetricSpec is exact; always return it even if allowApproximate is false.
        final DimensionTopNMetricSpec baseMetricSpec = new DimensionTopNMetricSpec(null, limitColumn.getDimensionComparator());
        topNMetricSpec = limitColumn.getDirection() == OrderByColumnSpec.Direction.ASCENDING ? baseMetricSpec : new InvertedTopNMetricSpec(baseMetricSpec);
    } else if (plannerContext.getPlannerConfig().isUseApproximateTopN()) {
        // ORDER BY metric
        final NumericTopNMetricSpec baseMetricSpec = new NumericTopNMetricSpec(limitColumn.getDimension());
        topNMetricSpec = limitColumn.getDirection() == OrderByColumnSpec.Direction.ASCENDING ? new InvertedTopNMetricSpec(baseMetricSpec) : baseMetricSpec;
    } else {
        return null;
    }
    final Pair<DataSource, Filtration> dataSourceFiltrationPair = getFiltration(dataSource, filter, virtualColumnRegistry);
    final DataSource newDataSource = dataSourceFiltrationPair.lhs;
    final Filtration filtration = dataSourceFiltrationPair.rhs;
    final List<PostAggregator> postAggregators = new ArrayList<>(grouping.getPostAggregators());
    if (sorting.getProjection() != null) {
        postAggregators.addAll(sorting.getProjection().getPostAggregators());
    }
    return new TopNQuery(newDataSource, getVirtualColumns(true), dimensionSpec, topNMetricSpec, Ints.checkedCast(sorting.getOffsetLimit().getLimit()), filtration.getQuerySegmentSpec(), filtration.getDimFilter(), Granularities.ALL, grouping.getAggregatorFactories(), postAggregators, ImmutableSortedMap.copyOf(plannerContext.getQueryContext()));
}