LogicalResultSinkToShortCircuitPointQuery.java

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package org.apache.doris.nereids.rules.rewrite;

import org.apache.doris.catalog.Column;
import org.apache.doris.catalog.OlapTable;
import org.apache.doris.nereids.StatementContext;
import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.trees.expressions.Cast;
import org.apache.doris.nereids.trees.expressions.EqualTo;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.SlotReference;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.logical.LogicalFilter;
import org.apache.doris.nereids.trees.plans.logical.LogicalOlapScan;
import org.apache.doris.qe.ConnectContext;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;

import java.util.List;
import java.util.Set;

/**
 * short circuit query optimization
 * pattern : select xxx from tbl where key = ?
 */
public class LogicalResultSinkToShortCircuitPointQuery implements RewriteRuleFactory {

    private Expression removeCast(Expression expression) {
        if (expression instanceof Cast) {
            return expression.child(0);
        }
        return expression;
    }

    private boolean filterMatchShortCircuitCondition(LogicalFilter<LogicalOlapScan> filter) {
        return filter.getConjuncts().stream().allMatch(
                // all conjuncts match with pattern `key = ?`
                expression -> (expression instanceof EqualTo)
                        && (removeCast(expression.child(0)).isKeyColumnFromTable()
                        || (expression.child(0) instanceof SlotReference
                        && ((SlotReference) expression.child(0)).getName().equals(Column.DELETE_SIGN)))
                        && expression.child(1).isLiteral());
    }

    private boolean scanMatchShortCircuitCondition(LogicalOlapScan olapScan) {
        if (!ConnectContext.get().getSessionVariable().isEnableShortCircuitQuery()) {
            return false;
        }
        OlapTable olapTable = olapScan.getTable();
        return olapTable.getEnableLightSchemaChange() && olapTable.getEnableUniqueKeyMergeOnWrite()
                        && olapTable.storeRowColumn();
    }

    // set short circuit flag and return the original plan
    private Plan shortCircuit(Plan root, OlapTable olapTable,
                Set<Expression> conjuncts, StatementContext statementContext) {
        // All key columns in conjuncts
        Set<String> colNames = Sets.newHashSet();
        for (Expression expr : conjuncts) {
            SlotReference slot = ((SlotReference) removeCast((expr.child(0))));
            if (slot.isKeyColumnFromTable()) {
                colNames.add(slot.getName());
            }
        }
        // set short circuit flag and modify nothing to the plan
        if (olapTable.getBaseSchemaKeyColumns().size() <= colNames.size()) {
            statementContext.setShortCircuitQuery(true);
        }
        return root;
    }

    @Override
    public List<Rule> buildRules() {
        return ImmutableList.of(
                RuleType.SHOR_CIRCUIT_POINT_QUERY.build(
                        logicalResultSink(logicalProject(logicalFilter(logicalOlapScan()
                            .when(this::scanMatchShortCircuitCondition)
                    ).when(this::filterMatchShortCircuitCondition)))
                        .thenApply(ctx -> {
                            return shortCircuit(ctx.root, ctx.root.child().child().child().getTable(),

                                        ctx.root.child().child().getConjuncts(), ctx.statementContext);
                        })),
                RuleType.SHOR_CIRCUIT_POINT_QUERY.build(
                        logicalResultSink(logicalFilter(logicalOlapScan()
                                .when(this::scanMatchShortCircuitCondition)
                        ).when(this::filterMatchShortCircuitCondition))
                                .thenApply(ctx -> {
                                    return shortCircuit(ctx.root, ctx.root.child().child().getTable(),
                                            ctx.root.child().getConjuncts(), ctx.statementContext);
                                }))
        );
    }
}