fix: [10kcp] Fix init rootcoord meta timeout (#38249)

issue: https://github.com/milvus-io/milvus/issues/37630

pr: https://github.com/milvus-io/milvus/pull/38248

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

internal/metastore/kv/rootcoord/kv_catalog.go

@@ -440,6 +440,7 @@ func (kc *Catalog) appendPartitionAndFieldsInfo(ctx context.Context, collMeta *p
 	return collection, nil
 }
 
+// TODO: This function will be invoked many times if there are many databases, leading to significant overhead.
 func (kc *Catalog) batchAppendPartitionAndFieldsInfo(ctx context.Context, collMeta []*pb.CollectionInfo,
 	ts typeutil.Timestamp,
 ) ([]*model.Collection, error) {

internal/metastore/kv/rootcoord/suffix_snapshot.go

@@ -434,18 +434,20 @@ func (ss *SuffixSnapshot) generateSaveExecute(kvs map[string]string, ts typeutil
 func (ss *SuffixSnapshot) LoadWithPrefix(key string, ts typeutil.Timestamp) ([]string, []string, error) {
 	// ts 0 case shall be treated as fetch latest/current value
 	if ts == 0 || ts == typeutil.MaxTimestamp {
-		keys, values, err := ss.MetaKv.LoadWithPrefix(key)
-		fks := keys[:0]   // make([]string, 0, len(keys))
-		fvs := values[:0] // make([]string, 0, len(values))
+		fks := make([]string, 0)
+		fvs := make([]string, 0)
 		// hide rootPrefix from return value
-		for i, k := range keys {
+		applyFn := func(key []byte, value []byte) error {
 			// filters tombstone
-			if ss.isTombstone(values[i]) {
-				continue
+			if ss.isTombstone(string(value)) {
+				return nil
 			}
-			fks = append(fks, ss.hideRootPrefix(k))
-			fvs = append(fvs, values[i])
+			fks = append(fks, ss.hideRootPrefix(string(key)))
+			fvs = append(fvs, string(value))
+			return nil
 		}
+
+		err := ss.MetaKv.WalkWithPrefix(key, PaginationSize, applyFn)
 		return fks, fvs, err
 	}
 	ss.Lock()