IvmAggTarget.java

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package org.apache.doris.mtmv.ivm.agg;

import org.apache.doris.mtmv.ivm.IvmUtil;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.Slot;

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

import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * Describes one aggregate target in the MV and its associated hidden state columns.
 *
 * <p>This is the stable form of {@link IvmAggTargetSpec}. Normalize first creates an
 * {@link IvmAggTargetSpec} while it is still deciding which hidden aggregate outputs to append. Once the normalized
 * Aggregate output slots are available, the spec is converted to this class and stored in {@link IvmAggMeta}. Delta
 * and apply rewrite use this target to dispatch the matching processor and to resolve visible/hidden state slots.
 */
public class IvmAggTarget {
    private final int ordinal;
    private final IvmAggFunctionKind functionKind;
    private final Slot visibleSlot;
    // Persisted hidden state column slots. For example, an AVG target has hidden SUM and COUNT states.
    private final Map<IvmAggStateKey, Slot> hiddenStateSlots;
    // Column carrying this target's own aggregate value state when the visible column does not
    // survive to the MV (see IvmAggFunctionProcessor#visibleColumnHoldsValueState). Null means the
    // visible column carries it: either because it reaches the MV as a visible column, or because
    // this target's old value is derived from hidden state instead (AVG, BITMAP_UNION_COUNT,
    // COUNT(*)). Apply reads the old value through getValueStateColumnName().
    private final Slot valueStateSlot;
    // True when the MV stores this aggregate's visible output under a name the analyzer generates (an
    // unnamed select item is renamed to __<function>_<index>), so apply cannot read the state back under
    // the aggregate's own column name and the state needs a carrier column of its own.
    private final boolean visibleColumnNameGenerated;
    // the expression(s) from the base scan that feed this aggregate
    // (empty for COUNT(*); may be Slot or compound Expression like v1+v2)
    private final List<Expression> exprArgs;

    public IvmAggTarget(int ordinal, IvmAggFunctionKind functionKind, Slot visibleSlot,
            Map<IvmAggStateKey, Slot> hiddenStateSlots, Slot valueStateSlot, boolean visibleColumnNameGenerated,
            List<Expression> exprArgs) {
        this.ordinal = ordinal;
        this.functionKind = Objects.requireNonNull(functionKind);
        this.visibleSlot = Objects.requireNonNull(visibleSlot);
        this.hiddenStateSlots = ImmutableMap.copyOf(hiddenStateSlots);
        this.valueStateSlot = valueStateSlot;
        this.visibleColumnNameGenerated = visibleColumnNameGenerated;
        this.exprArgs = ImmutableList.copyOf(exprArgs);
    }

    public int getOrdinal() {
        return ordinal;
    }

    public IvmAggFunctionKind getFunctionKind() {
        return functionKind;
    }

    public Slot getVisibleSlot() {
        return visibleSlot;
    }

    /** Whether this is a COUNT(*) target (no expression arguments). */
    public boolean isCountStar() {
        return functionKind == IvmAggFunctionKind.COUNT && exprArgs.isEmpty();
    }

    public Map<IvmAggStateKey, Slot> getHiddenStateSlots() {
        return hiddenStateSlots;
    }

    public Slot getHiddenStateSlot(IvmAggStateKey stateKey) {
        return hiddenStateSlots.get(stateKey);
    }

    /** Whether the MV stores this target's visible output under an analyzer-generated column name. */
    public boolean visibleColumnNameIsGenerated() {
        return visibleColumnNameGenerated;
    }

    /** Column carrying this target's own value state, or null when the visible column carries it. */
    public Slot getValueStateSlot() {
        return valueStateSlot;
    }

    /**
     * Name of the MV column apply reads this target's old value state from.
     *
     * <p>Processors whose apply merges the old value from the MV ({@code visibleColumnHoldsValueState})
     * read through this name, so a target whose visible column was dropped in favor of a materialized
     * hidden carrier resolves to that carrier instead.
     */
    public String getValueStateColumnName() {
        return valueStateSlot != null ? valueStateSlot.getName() : visibleSlot.getName();
    }

    /** Rebinds this target to the state slots materialized for it by normalize. */
    public IvmAggTarget withStateSlots(Slot newValueStateSlot, Map<IvmAggStateKey, Slot> newHiddenStateSlots) {
        if (Objects.equals(valueStateSlot, newValueStateSlot) && hiddenStateSlots.equals(newHiddenStateSlots)) {
            return this;
        }
        return new IvmAggTarget(ordinal, functionKind, visibleSlot, newHiddenStateSlots, newValueStateSlot,
                visibleColumnNameGenerated, exprArgs);
    }

    /**
     * Returns the canonical column name for the given state type.
     *
     * <p>If a physical hidden slot exists, its name is returned; otherwise the name
     * is generated via {@link IvmUtil#ivmAggHiddenColumnName}. This allows delta
     * sub-plan code to use a consistent name for both persisted and transient columns.
     */
    public String stateColumnName(IvmAggStateKey stateKey) {
        Slot slot = hiddenStateSlots.get(stateKey);
        return slot != null ? slot.getName()
                : IvmUtil.ivmAggHiddenColumnName(ordinal, stateKey.name());
    }

    public List<Expression> getExprArgs() {
        return exprArgs;
    }

    @Override
    public String toString() {
        return "IvmAggTarget{ordinal=" + ordinal + ", type=" + functionKind
                + ", visible=" + visibleSlot.getName()
                + ", hidden=" + hiddenStateSlots.keySet() + "}";
    }
}