etcdserverpb, clientv3: clarify WithLimit documentation

Fixes #7316

Documentation/dev-guide/api_reference_v3.md

@@ -636,7 +636,7 @@ Empty field.
 | ----- | ----------- | ---- |
 | key | default, no sorting lowest target value first highest target value first key is the first key for the range. If range_end is not given, the request only looks up key. | bytes |
 | range_end | range_end is the upper bound on the requested range [key, range_end). If range_end is '\0', the range is all keys >= key. If range_end is key plus one (e.g., "aa"+1 == "ab", "a\xff"+1 == "b"), then the range request gets all keys prefixed with key. If both key and range_end are '\0', then the range request returns all keys. | bytes |
-| limit | limit is a limit on the number of keys returned for the request. | int64 |
+| limit | limit is a limit on the number of keys returned for the request. When limit is set to 0, it is treated as no limit. | int64 |
 | revision | revision is the point-in-time of the key-value store to use for the range. If revision is less or equal to zero, the range is over the newest key-value store. If the revision has been compacted, ErrCompacted is returned as a response. | int64 |
 | sort_order | sort_order is the order for returned sorted results. | SortOrder |
 | sort_target | sort_target is the key-value field to use for sorting. | SortTarget |

clientv3/op.go

@@ -211,6 +211,7 @@ func WithLease(leaseID LeaseID) OpOption {
 }
 
 // WithLimit limits the number of results to return from 'Get' request.
+// If WithLimit is given a 0 limit, it is treated as no limit.
 func WithLimit(n int64) OpOption { return func(op *Op) { op.limit = n } }
 
 // WithRev specifies the store revision for 'Get' request.

etcdserver/etcdserverpb/rpc.pb.go

@@ -232,7 +232,8 @@ type RangeRequest struct {
 	// then the range request gets all keys prefixed with key.
 	// If both key and range_end are '\0', then the range request returns all keys.
 	RangeEnd []byte `protobuf:"bytes,2,opt,name=range_end,json=rangeEnd,proto3" json:"range_end,omitempty"`
-	// limit is a limit on the number of keys returned for the request.
+	// limit is a limit on the number of keys returned for the request. When limit is set to 0,
+	// it is treated as no limit.
 	Limit int64 `protobuf:"varint,3,opt,name=limit,proto3" json:"limit,omitempty"`
 	// revision is the point-in-time of the key-value store to use for the range.
 	// If revision is less or equal to zero, the range is over the newest key-value store.

etcdserver/etcdserverpb/rpc.proto

@@ -356,7 +356,8 @@ message RangeRequest {
   // then the range request gets all keys prefixed with key.
   // If both key and range_end are '\0', then the range request returns all keys.
   bytes range_end = 2;
-  // limit is a limit on the number of keys returned for the request.
+  // limit is a limit on the number of keys returned for the request. When limit is set to 0,
+  // it is treated as no limit.
   int64 limit = 3;
   // revision is the point-in-time of the key-value store to use for the range.
   // If revision is less or equal to zero, the range is over the newest key-value store.