[GitHub] [incubator-shardingsphere] lightning-pro commented on issue #3670: if null value is not supported?

[GitBox <gi...@apache.org>]

lightning-pro commented on issue #3670: if null value is not supported?
URL: https://github.com/apache/incubator-shardingsphere/issues/3670#issuecomment-562088575
 
 
   my tables split to 17 tables from 0 to 16
   when execute below sql, which the value of COMMENTS field is null
   ```
   SELECT PRIM.SMS_NUM_ID, PRIM.PUBLIC_VIEW_ID,PRIM.COMMENTS
   FROM CUSTOMER_SMS_NUM PRIM WHERE (PRIM.SMS_NUM_ID >= 1 AND PRIM.SMS_NUM_ID <= 18) order by PRIM.SMS_NUM_ID
   ```
   the above sql work perfect
   
   when execute like below, there will be a row with all null values and other rows ok
   ```
   SELECT PRIM.SMS_NUM_ID, PRIM.PUBLIC_VIEW_ID,PRIM.COMMENTS
   FROM CUSTOMER_SMS_NUM PRIM WHERE (PRIM.SMS_NUM_ID >= 1 AND PRIM.SMS_NUM_ID <= 19) order by PRIM.SMS_NUM_ID
   ```
   
   while increase the bigger range with 20,21,22....the rows with null values will increase randomly.
   
   but when I remove the PRIM.COMMENTS fields, everything is ok. return the expected records
   
   the sharding field is SMS_NUM_ID with Integer value
    and my sharding algorithm as belows
   RangeShardingAlgorithm
   
   ```
   @Override
       public Collection<String> doSharding(Collection<String> availableTargetNames, RangeShardingValue<Integer> shardingValue) {
           Collection<String> result = new HashSet<>();
           if(shardingValue.getValueRange().hasUpperBound()){
               for (int i = shardingValue.getValueRange().lowerEndpoint(); i <= shardingValue.getValueRange().upperEndpoint(); i++) {
                   for (String each : availableTargetNames) {
                       if (each.endsWith(String.valueOf(i % availableTargetNames.size()))) {
                           result.add(each);
                       }
                   }
               }
           }else {
               result = availableTargetNames;
           }
   
           return result;
       }
   ```
   PreciseShardingAlgorithm
   ```
   @Override
       public String doSharding(Collection<String> collection, PreciseShardingValue<Integer> preciseShardingValue) {
           for (String each : collection) {
               if (each.endsWith(String.valueOf(preciseShardingValue.getValue() % collection.size()))) {
                   return each;
               }
           }
           return null;
       }
   ```

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