[opt](nereids) catch all exceptions in StatsCalculator

fe/fe-core/src/main/java/org/apache/doris/nereids/stats/ExpressionEstimation.java

@@ -95,12 +95,15 @@
 import org.apache.doris.nereids.trees.expressions.literal.Literal;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
 import org.apache.doris.nereids.types.DataType;
+import org.apache.doris.qe.ConnectContext;
 import org.apache.doris.statistics.ColumnStatistic;
 import org.apache.doris.statistics.ColumnStatisticBuilder;
 import org.apache.doris.statistics.Statistics;
 
 import com.google.common.base.Preconditions;
 import org.apache.commons.collections.CollectionUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
 
 import java.time.Instant;
 import java.time.LocalDate;
@@ -112,7 +115,7 @@
  * Used to estimate for expressions that not producing boolean value.
  */
 public class ExpressionEstimation extends ExpressionVisitor<ColumnStatistic, Statistics> {
-
+    public static final Logger LOG = LogManager.getLogger(ExpressionEstimation.class);
     public static final long DAYS_FROM_0_TO_1970 = 719528;
     public static final long DAYS_FROM_0_TO_9999 = 3652424;
     private static final ExpressionEstimation INSTANCE = new ExpressionEstimation();
@@ -121,11 +124,20 @@ public class ExpressionEstimation extends ExpressionVisitor<ColumnStatistic, Sta
      * returned columnStat is newly created or a copy of stats
      */
     public static ColumnStatistic estimate(Expression expression, Statistics stats) {
-        ColumnStatistic columnStatistic = expression.accept(INSTANCE, stats);
-        if (columnStatistic == null) {
-            return ColumnStatistic.UNKNOWN;
+        try {
+            ColumnStatistic columnStatistic = expression.accept(INSTANCE, stats);
+            if (columnStatistic == null) {
+                return ColumnStatistic.createUnknownByDataType(expression.getDataType());
+            }
+            return columnStatistic;
+        } catch (Exception e) {
+            // in regression test, feDebug is true so that the exception is thrown in order to detect problems.
+            if (ConnectContext.get() != null && ConnectContext.get().getSessionVariable().feDebug) {
+                throw e;
+            }
+            LOG.warn("ExpressionEstimation failed : " + expression, e);
+            return ColumnStatistic.createUnknownByDataType(expression.getDataType());
         }
-        return columnStatistic;
     }
 
     @Override

fe/fe-core/src/main/java/org/apache/doris/nereids/stats/StatsCalculator.java

@@ -301,13 +301,33 @@ public static void estimate(GroupExpression groupExpression, CascadesContext con
 
     private void estimate() {
         Plan plan = groupExpression.getPlan();
-        Statistics newStats = plan.accept(this, null);
+        Statistics newStats;
+        try {
+            newStats = plan.accept(this, null);
+        } catch (Exception e) {
+            // throw exception in debug mode
+            if (ConnectContext.get() != null && ConnectContext.get().getSessionVariable().feDebug) {
+                throw e;
+            }
+            LOG.warn("stats calculation failed, plan " + plan.toString(), e);
+            // use unknown stats or the first child's stats
+            if (plan.children().isEmpty() || !(plan.child(0) instanceof GroupPlan)) {
+                Map<Expression, ColumnStatistic> columnStatisticMap = new HashMap<>();
+                for (Slot slot : plan.getOutput()) {
+                    columnStatisticMap.put(slot, ColumnStatistic.createUnknownByDataType(slot.getDataType()));
+                }
+                newStats = new Statistics(1, 1, columnStatisticMap);
+            } else {
+                newStats = ((GroupPlan) plan.child(0)).getStats();
+            }
+        }
         newStats.normalizeColumnStatistics();
 
         // We ensure that the rowCount remains unchanged in order to make the cost of each plan comparable.
+        final Statistics tmpStats = newStats;
         if (groupExpression.getOwnerGroup().getStatistics() == null) {
             boolean isReliable = groupExpression.getPlan().getExpressions().stream()
-                    .noneMatch(e -> newStats.isInputSlotsUnknown(e.getInputSlots()));
+                    .noneMatch(e -> tmpStats.isInputSlotsUnknown(e.getInputSlots()));
             groupExpression.getOwnerGroup().setStatsReliable(isReliable);
             groupExpression.getOwnerGroup().setStatistics(newStats);
         } else {

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/plans/GroupPlan.java

@@ -62,7 +62,7 @@ public List<? extends Expression> getExpressions() {
 
     @Override
     public Statistics getStats() {
-        throw new IllegalStateException("GroupPlan can not invoke getStats()");
+        return group.getStatistics();
     }
 
     @Override

fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java

@@ -2271,6 +2271,12 @@ public void setDetailShapePlanNodes(String detailShapePlanNodes) {
                 "use other health replica when the use_fix_replica meet error" })
     public boolean fallbackOtherReplicaWhenFixedCorrupt = false;
 
+    public static final String FE_DEBUG = "fe_debug";
+    @VariableMgr.VarAttr(name = FE_DEBUG, needForward = true, fuzzy = true,
+            description = {"when set true, FE will throw exceptions instead swallow them. This is used for test",
+                    "when set true, FE will throw exceptions instead swallow them. This is used for test"})
+    public boolean feDebug = false;
+
     @VariableMgr.VarAttr(name = SHOW_ALL_FE_CONNECTION,
             description = {"when it's true show processlist statement list all fe's connection",
                     "当变量为true时，show processlist命令展示所有fe的连接"})
@@ -2505,6 +2511,7 @@ public boolean isEnableESParallelScroll() {
     @SuppressWarnings("checkstyle:Indentation")
     public void initFuzzyModeVariables() {
         Random random = new SecureRandom();
+        this.feDebug = true;
         this.parallelPipelineTaskNum = random.nextInt(8);
         this.parallelPrepareThreshold = random.nextInt(32) + 1;
         this.enableCommonExprPushdown = random.nextBoolean();

fe/fe-core/src/main/java/org/apache/doris/statistics/ColumnStatistic.java

@@ -22,6 +22,8 @@
 import org.apache.doris.catalog.Type;
 import org.apache.doris.common.AnalysisException;
 import org.apache.doris.datasource.InternalCatalog;
+import org.apache.doris.nereids.types.DataType;
+import org.apache.doris.nereids.types.coercion.CharacterType;
 import org.apache.doris.persist.gson.GsonUtils;
 import org.apache.doris.statistics.util.StatisticsUtil;
 
@@ -369,4 +371,28 @@ public boolean isUnKnown() {
     public ColumnStatistic withAvgSizeByte(double avgSizeByte) {
         return new ColumnStatisticBuilder(this).setAvgSizeByte(avgSizeByte).build();
     }
+
+    public static ColumnStatistic createUnknownByDataType(DataType dataType) {
+        if (dataType instanceof CharacterType) {
+            return new ColumnStatisticBuilder(1)
+                    .setAvgSizeByte(Math.max(1, Math.min(dataType.width(), CharacterType.DEFAULT_WIDTH)))
+                    .setNdv(1)
+                    .setNumNulls(1)
+                    .setMaxValue(Double.POSITIVE_INFINITY)
+                    .setMinValue(Double.NEGATIVE_INFINITY)
+                    .setIsUnknown(true)
+                    .setUpdatedTime("")
+                    .build();
+        } else {
+            return new ColumnStatisticBuilder(1)
+                    .setAvgSizeByte(dataType.width())
+                    .setNdv(1)
+                    .setNumNulls(1)
+                    .setMaxValue(Double.POSITIVE_INFINITY)
+                    .setMinValue(Double.NEGATIVE_INFINITY)
+                    .setIsUnknown(true)
+                    .setUpdatedTime("")
+                    .build();
+        }
+    }
 }

fe/fe-core/src/test/java/org/apache/doris/nereids/stats/ExpressionEstimationTest.java

@@ -447,4 +447,13 @@ public void testLiteral() {
         Assertions.assertEquals(est.avgSizeByte, 1);
         Assertions.assertEquals(est.numNulls, 1);
     }
+
+    @Test
+    public void testThrowException() {
+        SlotReference a = new SlotReference("a", StringType.INSTANCE);
+        Cast cast = new Cast(a, DateType.INSTANCE);
+        // do not throw any exception
+        ColumnStatistic est = ExpressionEstimation.estimate(cast, null);
+        Assertions.assertTrue(est.isUnKnown());
+    }
 }