fix: merged chunk

Author: astandrik

src/services/api/viewer.ts

@@ -1,4 +1,9 @@
 import type {PlanToSvgQueryParams} from '../../store/reducers/planToSvg';
+import {
+    isQueryResponseChunk,
+    isSessionChunk,
+    isStreamDataChunk,
+} from '../../store/reducers/query/utils';
 import type {TMetaInfo} from '../../types/api/acl';
 import type {TQueryAutocomplete} from '../../types/api/autocomplete';
 import type {CapabilitiesResponse} from '../../types/api/capabilities';
@@ -422,8 +427,31 @@ export class ViewerAPI extends BaseYdbAPI {
                         state: parserState,
                     });
                     parserState = state;
+                    let mergedChunk = null;
+
                     for (const chunk of chunks) {
-                        onChunk?.(chunk);
+                        if (isSessionChunk(chunk) || isQueryResponseChunk(chunk)) {
+                            // First dispatch any accumulated data chunk
+                            if (mergedChunk) {
+                                onChunk?.(mergedChunk);
+                                mergedChunk = null;
+                            }
+                            // Then dispatch control chunk
+                            onChunk?.(chunk);
+                        } else if (isStreamDataChunk(chunk)) {
+                            if (mergedChunk) {
+                                // Merge rows from subsequent chunks
+                                mergedChunk.result.rows.push(...chunk.result.rows);
+                            } else {
+                                // First data chunk - use as base with columns
+                                mergedChunk = chunk;
+                            }
+                        }
+                    }
+
+                    // Dispatch any remaining merged chunk
+                    if (mergedChunk) {
+                        onChunk?.(mergedChunk);
                     }
                 },
             },