support multiple ranges for MetadataTableValuedFunction

Author: suxiaogang223

fe/fe-core/src/main/java/org/apache/doris/datasource/tvf/source/MetadataScanNode.java

@@ -27,6 +27,7 @@
 import org.apache.doris.system.Backend;
 import org.apache.doris.tablefunction.MetadataTableValuedFunction;
 import org.apache.doris.thrift.TMetaScanNode;
+import org.apache.doris.thrift.TMetaScanRange;
 import org.apache.doris.thrift.TNetworkAddress;
 import org.apache.doris.thrift.TPlanNode;
 import org.apache.doris.thrift.TPlanNodeType;
@@ -70,19 +71,21 @@ protected void toThrift(TPlanNode planNode) {
 
     @Override
     protected void createScanRangeLocations() throws UserException {
-        TScanRange scanRange = new TScanRange();
-        scanRange.setMetaScanRange(tvf.getMetaScanRange());
-        // set location
-        TScanRangeLocation location = new TScanRangeLocation();
-        Backend backend = backendPolicy.getNextBe();
-        location.setBackendId(backend.getId());
-        location.setServer(new TNetworkAddress(backend.getHost(), backend.getBePort()));
-
-        TScanRangeLocations locations = new TScanRangeLocations();
-        locations.addToLocations(location);
-        locations.setScanRange(scanRange);
-
-        scanRangeLocations.add(locations);
+        for (TMetaScanRange metaScanRange : tvf.getMetaScanRanges()) {
+            TScanRange scanRange = new TScanRange();
+            scanRange.setMetaScanRange(metaScanRange);
+
+            TScanRangeLocation location = new TScanRangeLocation();
+            Backend backend = backendPolicy.getNextBe();
+            location.setBackendId(backend.getId());
+            location.setServer(new TNetworkAddress(backend.getHost(), backend.getBePort()));
+
+            TScanRangeLocations locations = new TScanRangeLocations();
+            locations.addToLocations(location);
+            locations.setScanRange(scanRange);
+
+            scanRangeLocations.add(locations);
+        }
     }
 
     @Override

fe/fe-core/src/main/java/org/apache/doris/tablefunction/MetadataTableValuedFunction.java

@@ -27,6 +27,8 @@
 import org.apache.doris.thrift.TMetadataTableRequestParams;
 import org.apache.doris.thrift.TMetadataType;
 
+import java.util.List;
+
 public abstract class MetadataTableValuedFunction extends TableValuedFunctionIf {
 
     public static Integer getColumnIndexFromColumnName(TMetadataType type, String columnName,
@@ -60,6 +62,12 @@ public static Integer getColumnIndexFromColumnName(TMetadataType type, String co
 
     public abstract TMetaScanRange getMetaScanRange();
 
+    public List<TMetaScanRange> getMetaScanRanges() {
+        // most of the time, we only have one scan range,
+        // but you can override this method to return multiple ranges
+        return List.of(getMetaScanRange());
+    }
+
     @Override
     public ScanNode getScanNode(PlanNodeId id, TupleDescriptor desc, SessionVariable sv) {
         return new MetadataScanNode(id, desc, this);