sandynz commented on issue #6729:
URL: https://github.com/apache/shardingsphere/issues/6729#issuecomment-671006899
Reason analyze of "sql route to 2 physics tables, but not one".
```
ShardingStandardRoutingEngine.java
private Collection<DataNode> routeTables(final ShardingRule
shardingRule, final TableRule tableRule, final String routedDataSource, final
List<RouteValue> tableShardingValues) {
Collection<String> availableTargetTables =
tableRule.getActualTableNames(routedDataSource);
Collection<String> routedTables = new
LinkedHashSet<>(tableShardingValues.isEmpty() ? availableTargetTables
:
shardingRule.getTableShardingStrategy(tableRule).doSharding(availableTargetTables,
tableShardingValues, properties));
Collection<DataNode> result = new LinkedList<>();
for (String each : routedTables) {
result.add(new DataNode(routedDataSource, each));
}
return result;
}
tableShardingValues is empty, just return availableTargetTables.
private List<RouteValue> getShardingValuesFromShardingConditions(final
ShardingRule shardingRule, final Collection<String> shardingColumns, final
ShardingCondition shardingCondition) {
List<RouteValue> result = new ArrayList<>(shardingColumns.size());
for (RouteValue each : shardingCondition.getRouteValues()) {
Optional<BindingTableRule> bindingTableRule =
shardingRule.findBindingTableRule(logicTableName);
if ((logicTableName.equals(each.getTableName()) ||
bindingTableRule.isPresent() &&
bindingTableRule.get().hasLogicTable(logicTableName))
&& shardingColumns.contains(each.getColumnName())) {
result.add(each);
}
}
return result;
}
shardingCondition.getRouteValues() result is empty, so result is empty.
```
Trace shardingCondition.routeValues
```
ShardingRouteDecorator.java
private ShardingConditions getShardingConditions(final List<Object>
parameters, final SQLStatementContext sqlStatementContext,
final SchemaMetaData
schemaMetaData, final ShardingRule shardingRule) {
if (sqlStatementContext.getSqlStatement() instanceof DMLStatement) {
if (sqlStatementContext instanceof InsertStatementContext) {
return new ShardingConditions(new
InsertClauseShardingConditionEngine(shardingRule,
schemaMetaData).createShardingConditions((InsertStatementContext)
sqlStatementContext, parameters));
}
return new ShardingConditions(new
WhereClauseShardingConditionEngine(shardingRule,
schemaMetaData).createShardingConditions(sqlStatementContext, parameters));
}
return new ShardingConditions(Collections.emptyList());
}
```
```
InsertClauseShardingConditionEngine.java
private ShardingCondition createShardingCondition(final String
tableName, final Iterator<String> columnNames, final InsertValueContext
insertValueContext, final List<Object> parameters) {
ShardingCondition result = new ShardingCondition();
SPITimeService timeService = new SPITimeService();
for (ExpressionSegment each :
insertValueContext.getValueExpressions()) {
String columnName = columnNames.next();
if (shardingRule.isShardingColumn(columnName, tableName)) {
if (each instanceof SimpleExpressionSegment) {
result.getRouteValues().add(new
ListRouteValue<>(columnName, tableName,
Collections.singletonList(getRouteValue((SimpleExpressionSegment) each,
parameters))));
} else if (ExpressionConditionUtils.isNowExpression(each)) {
result.getRouteValues().add(new
ListRouteValue<>(columnName, tableName,
Collections.singletonList(timeService.getTime())));
} else if (ExpressionConditionUtils.isNullExpression(each)) {
throw new ShardingSphereException("Insert clause
sharding column can't be null.");
}
}
}
return result;
}
insertValueContext.getValueExpressions() elements are
CommonExpressionSegment,
not instanceof SimpleExpressionSegment, it should be
ParameterMarkerExpressionSegment,
the same reason as problem 1.
```
createShardingCondition example:
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