/// <summary>
/// When resuming an order by query we need to filter the document producers.
/// </summary>
/// <param name="producer">The producer to filter down.</param>
/// <param name="sortOrders">The sort orders.</param>
/// <param name="continuationToken">The continuation token.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>A task to await on.</returns>
private async Task FilterAsync(
ItemProducerTree producer,
SortOrder[] sortOrders,
OrderByContinuationToken continuationToken,
CancellationToken cancellationToken)
{
// When we resume a query on a partition there is a possibility that we only read a partial page from the backend
// meaning that will we repeat some documents if we didn't do anything about it.
// The solution is to filter all the documents that come before in the sort order, since we have already emitted them to the client.
// The key is to seek until we get an order by value that matches the order by value we left off on.
// Once we do that we need to seek to the correct _rid within the term,
// since there might be many documents with the same order by value we left off on.
foreach (ItemProducerTree tree in producer)
{
if (!ResourceId.TryParse(continuationToken.Rid, out ResourceId continuationRid))
{
throw new CosmosException(
statusCode: HttpStatusCode.BadRequest,
message: $"Invalid Rid in the continuation token {continuationToken.CompositeContinuationToken.Token} for OrderBy~Context.");
}
Dictionary <string, ResourceId> resourceIds = new Dictionary <string, ResourceId>();
int itemToSkip = continuationToken.SkipCount;
bool continuationRidVerified = false;
while (true)
{
OrderByQueryResult orderByResult = new OrderByQueryResult(tree.Current);
// Throw away documents until it matches the item from the continuation token.
int cmp = 0;
for (int i = 0; i < sortOrders.Length; ++i)
{
cmp = ItemComparer.Instance.Compare(
continuationToken.OrderByItems[i].Item,
orderByResult.OrderByItems[i].Item);
if (cmp != 0)
{
cmp = sortOrders[i] != SortOrder.Descending ? cmp : -cmp;
break;
}
}
if (cmp < 0)
{
// We might have passed the item due to deletions and filters.
break;
}
if (cmp == 0)
{
ResourceId rid;
if (!resourceIds.TryGetValue(orderByResult.Rid, out rid))
{
if (!ResourceId.TryParse(orderByResult.Rid, out rid))
{
throw new CosmosException(
statusCode: HttpStatusCode.BadRequest,
message: $"Invalid Rid in the continuation token {continuationToken.CompositeContinuationToken.Token} for OrderBy~Context~TryParse.");
}
resourceIds.Add(orderByResult.Rid, rid);
}
if (!continuationRidVerified)
{
if (continuationRid.Database != rid.Database || continuationRid.DocumentCollection != rid.DocumentCollection)
{
throw new CosmosException(
statusCode: HttpStatusCode.BadRequest,
message: $"Invalid Rid in the continuation token {continuationToken.CompositeContinuationToken.Token} for OrderBy~Context.");
}
continuationRidVerified = true;
}
// Once the item matches the order by items from the continuation tokens
// We still need to remove all the documents that have a lower rid in the rid sort order.
// If there is a tie in the sort order the documents should be in _rid order in the same direction as the first order by field.
// So if it's ORDER BY c.age ASC, c.name DESC the _rids are ASC
// If ti's ORDER BY c.age DESC, c.name DESC the _rids are DESC
cmp = continuationRid.Document.CompareTo(rid.Document);
if (sortOrders[0] == SortOrder.Descending)
{
cmp = -cmp;
}
// We might have passed the item due to deletions and filters.
// We also have a skip count for JOINs
if (cmp < 0 || (cmp == 0 && itemToSkip-- <= 0))
{
break;
}
}
(bool successfullyMovedNext, QueryResponseCore? failureResponse)moveNextResponse = await tree.MoveNextAsync(cancellationToken);
if (!moveNextResponse.successfullyMovedNext)
{
if (moveNextResponse.failureResponse != null)
{
this.FailureResponse = moveNextResponse.failureResponse;
}
break;
}
}
}
}
public void TestRoundTripAsCosmosElement()
{
CompositeContinuationToken compositeContinuationToken = new CompositeContinuationToken()
{
Token = "someToken",
Range = new Documents.Routing.Range <string>("asdf", "asdf", false, false),
};
List <OrderByItem> orderByItems = new List <OrderByItem>()
{
new OrderByItem(CosmosObject.Create(new Dictionary <string, CosmosElement>()
{
{ "item", CosmosString.Create("asdf") }
})),
new OrderByItem(CosmosObject.Create(new Dictionary <string, CosmosElement>()
{
{ "item", CosmosInt64.Create(1337) }
})),
new OrderByItem(CosmosObject.Create(new Dictionary <string, CosmosElement>()
{
{ "item", CosmosBinary.Create(new byte[] { 1, 2, 3 }) }
})),
};
string rid = "someRid";
int skipCount = 42;
string filter = "someFilter";
OrderByContinuationToken orderByContinuationToken = new OrderByContinuationToken(
compositeContinuationToken,
orderByItems,
rid,
skipCount,
filter);
CosmosElement cosmosElementToken = OrderByContinuationToken.ToCosmosElement(orderByContinuationToken);
Assert.AreEqual(
@"{""compositeToken"":{""token"":""someToken"",""range"":{""min"":""asdf"",""max"":""asdf""}},""orderByItems"":[{""item"":""asdf""},{""item"":LL1337},{""item"":BAQID}],""rid"":""someRid"",""skipCount"":42,""filter"":""someFilter""}",
cosmosElementToken.ToString());
TryCatch <OrderByContinuationToken> tryOrderByContinuationTokenFromCosmosElement = OrderByContinuationToken.TryCreateFromCosmosElement(cosmosElementToken);
Assert.IsTrue(tryOrderByContinuationTokenFromCosmosElement.Succeeded);
OrderByContinuationToken orderByContinuationTokenFromCosmosElement = tryOrderByContinuationTokenFromCosmosElement.Result;
Assert.IsNotNull(orderByContinuationTokenFromCosmosElement);
Assert.AreEqual(cosmosElementToken.ToString(), OrderByContinuationToken.ToCosmosElement(orderByContinuationTokenFromCosmosElement).ToString());
}