theodoretsai opened a new issue, #22572:
URL: https://github.com/apache/shardingsphere/issues/22572
I'm trying to implement the ComplexKeyShardingAlgorithm and I'm having an
issue with IN statement queries when only a partial match is found.
For example for the routing configuration as following (Keeping it simple
with one keyed column):
Default Datasource = DS1
Default Table = Table1
Strategy 1: Value A -> DS1.table1
Strategy 2: Value B -> DS1.table2
Strategy 3: Value C -> DS2.table1
Strategy 4: Value D -> DS2.table2
with the following query:
```
SELECT *
FROM logical_table
WHERE column = C OR column = D
```
Th Sharding Result should be :
`DS2.table1 because it C is routed there by stratedy 3`
`DS1.table1 because D doesn't match any strategyand default is selected`
now if I execute the query like this
```
SELECT *
FROM logical_table
WHERE column IN (C, D)
```
how am I supposed to get the same result of the OR statement?
This is the code from the StandardRoutingEngine:
```
private Collection<DataNode> route0(final TableRule tableRule, final
List<RouteValue> databaseShardingValues,
final List<RouteValue>
tableShardingValues) {
Collection<String> routedDataSources = routeDataSources(tableRule,
databaseShardingValues);
Collection<DataNode> result = new LinkedList<>();
for (String each : routedDataSources) {
result.addAll(routeTables(tableRule, each, tableShardingValues));
}
return result;
}
```
When routing datasources it's pretty straitght forward, select the ones from
strategies that match, and if there's sharding value that doesn't match any add
the Default datasource as well.
Now when routing tables for each datasource it becomes tricky: when doing it
with tables from a datasource match I should just return the table value that
match, but how do I know when I am sharding table values of the default
datasource which was selected because there was an unconsidered sharding value?
(that no strategy matched)
Since I only have the tableShardingValues information available when
implementing the doSharding method it's really hard to do so. I guess it is
possible but would be too complicated, and probably not very friendly for
performance, and would require some stateful events to be cached somewhere.
I hope I am missing something here and that there's a better way to do this,
some help would be very appreciated.
Thank you very much.
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