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[cherry-pick] prohibit agg or groupby pushdown on double read (#1004) #1027

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Aug 15, 2019
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[cherry-pick] prohibit agg or groupby pushdown on double read (#1004) #1027

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107 changes: 64 additions & 43 deletions tikv-client/src/main/java/com/pingcap/tikv/meta/TiDAGRequest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.pingcap.tidb.tipb.*;
import com.pingcap.tidb.tipb.DAGRequest.Builder;
import com.pingcap.tikv.codec.KeyUtils;
import com.pingcap.tikv.exception.DAGRequestException;
import com.pingcap.tikv.exception.TiClientInternalException;
Expand Down Expand Up @@ -462,59 +463,78 @@ else if (col.getColumnInfo().isPrimaryKey() && tableInfo.isPkHandle()) {
}

if (!getGroupByItems().isEmpty() || !getAggregates().isEmpty()) {
// only allow table scan or covering index scan push down groupby and agg
if (!isIndexDoubleScan || (isGroupByCoveredByIndex() && isAggregateCoveredByIndex())) {
Aggregation.Builder aggregationBuilder = Aggregation.newBuilder();
getGroupByItems()
.forEach(
tiByItem ->
aggregationBuilder.addGroupBy(
ProtoConverter.toProto(tiByItem.getExpr(), colOffsetInFieldMap)));
getAggregates()
.forEach(
tiExpr ->
aggregationBuilder.addAggFunc(
ProtoConverter.toProto(tiExpr, colOffsetInFieldMap)));
executorBuilder.setTp(ExecType.TypeAggregation);
dagRequestBuilder.addExecutors(executorBuilder.setAggregation(aggregationBuilder));
executorBuilder.clear();
addPushDownGroupBys();
addPushDownAggregates();
pushDownAggAndGroupBy(dagRequestBuilder, executorBuilder, colOffsetInFieldMap);
} else {
return dagRequestBuilder;
}
}

if (!getOrderByItems().isEmpty()) {
if (!isIndexDoubleScan || isOrderByCoveredByIndex()) {
TopN.Builder topNBuilder = TopN.newBuilder();
getOrderByItems()
.forEach(
tiByItem ->
topNBuilder.addOrderBy(
com.pingcap.tidb.tipb.ByItem.newBuilder()
.setExpr(
ProtoConverter.toProto(tiByItem.getExpr(), colOffsetInFieldMap))
.setDesc(tiByItem.isDesc())));
executorBuilder.setTp(ExecType.TypeTopN);
topNBuilder.setLimit(getLimit());
dagRequestBuilder.addExecutors(executorBuilder.setTopN(topNBuilder));
executorBuilder.clear();
addPushDownOrderBys();
// only allow table scan or covering index scan push down orderby
pushDownOrderBy(dagRequestBuilder, executorBuilder, colOffsetInFieldMap);
}
} else if (getLimit() != 0) {
if (!isIndexDoubleScan) {
Limit.Builder limitBuilder = Limit.newBuilder();
limitBuilder.setLimit(getLimit());
executorBuilder.setTp(ExecType.TypeLimit);
dagRequestBuilder.addExecutors(executorBuilder.setLimit(limitBuilder));
executorBuilder.clear();
addPushDownLimits();
pushDownLimit(dagRequestBuilder, executorBuilder);
}
}

return dagRequestBuilder;
}

private void pushDownLimit(
DAGRequest.Builder dagRequestBuilder, Executor.Builder executorBuilder) {
Limit.Builder limitBuilder = Limit.newBuilder();
limitBuilder.setLimit(getLimit());
executorBuilder.setTp(ExecType.TypeLimit);
dagRequestBuilder.addExecutors(executorBuilder.setLimit(limitBuilder));
executorBuilder.clear();
addPushDownLimits();
}

private void pushDownOrderBy(
DAGRequest.Builder dagRequestBuilder,
Executor.Builder executorBuilder,
Map<ColumnRef, Integer> colOffsetInFieldMap) {
TopN.Builder topNBuilder = TopN.newBuilder();
getOrderByItems()
.forEach(
tiByItem ->
topNBuilder.addOrderBy(
com.pingcap.tidb.tipb.ByItem.newBuilder()
.setExpr(ProtoConverter.toProto(tiByItem.getExpr(), colOffsetInFieldMap))
.setDesc(tiByItem.isDesc())));
executorBuilder.setTp(ExecType.TypeTopN);
topNBuilder.setLimit(getLimit());
dagRequestBuilder.addExecutors(executorBuilder.setTopN(topNBuilder));
executorBuilder.clear();
addPushDownOrderBys();
}

private void pushDownAggAndGroupBy(
DAGRequest.Builder dagRequestBuilder,
Executor.Builder executorBuilder,
Map<ColumnRef, Integer> colOffsetInFieldMap) {
Aggregation.Builder aggregationBuilder = Aggregation.newBuilder();
getGroupByItems()
.forEach(
tiByItem ->
aggregationBuilder.addGroupBy(
ProtoConverter.toProto(tiByItem.getExpr(), colOffsetInFieldMap)));
getAggregates()
.forEach(
tiExpr ->
aggregationBuilder.addAggFunc(ProtoConverter.toProto(tiExpr, colOffsetInFieldMap)));
executorBuilder.setTp(ExecType.TypeAggregation);
dagRequestBuilder.addExecutors(executorBuilder.setAggregation(aggregationBuilder));
executorBuilder.clear();
addPushDownGroupBys();
addPushDownAggregates();
}

private boolean isExpressionCoveredByIndex(Expression expr) {
Set<String> indexColumnRefSet =
indexInfo
Expand All @@ -523,10 +543,11 @@ private boolean isExpressionCoveredByIndex(Expression expr) {
.filter(x -> !x.isPrefixIndex())
.map(TiIndexColumn::getName)
.collect(Collectors.toSet());
return PredicateUtils.extractColumnRefFromExpression(expr)
.stream()
.map(ColumnRef::getName)
.allMatch(indexColumnRefSet::contains);
return !isDoubleRead()
&& PredicateUtils.extractColumnRefFromExpression(expr)
.stream()
.map(ColumnRef::getName)
.allMatch(indexColumnRefSet::contains);
}

private boolean isGroupByCoveredByIndex() {
Expand Down Expand Up @@ -659,7 +680,7 @@ int getTimeZoneOffset() {
* @param mode truncate mode
* @return a TiDAGRequest
*/
public TiDAGRequest setTruncateMode(TiDAGRequest.TruncateMode mode) {
TiDAGRequest setTruncateMode(TiDAGRequest.TruncateMode mode) {
flags = requireNonNull(mode, "mode is null").mask(flags);
return this;
}
Expand Down Expand Up @@ -711,7 +732,7 @@ public TiDAGRequest addAggregate(Expression expr, DataType targetType) {
return this;
}

public List<Expression> getAggregates() {
List<Expression> getAggregates() {
return aggregates.stream().map(p -> p.first).collect(Collectors.toList());
}

Expand Down Expand Up @@ -920,7 +941,7 @@ public void setIsDoubleRead(boolean isDoubleRead) {
*
* @return boolean
*/
public boolean isCoveringIndexScan() {
private boolean isCoveringIndexScan() {
return hasIndex() && !isDoubleRead();
}

Expand Down