ReadItemAsync Cosmos DB

Question

I have a cosmos db container with below fields (id,Category,Type). The partition key is Category. While using the Below query I need to pass Partition key also. But I have only ID value. How do I perform the operation using ReadItemAsync?. I am getting not found error.

private async Task<T> GetItem(string id)
        {
            
                ItemResponse<T> response = await this.MainContainer.ReadItemAsync<T>(id, new PartitionKey(id));
                return response.Resource;
         }

Vivek Sharma · Accepted Answer · 2020-09-06T12:57:09.137

7

If you do not know the partition key value, you can use GetItemQueryable instead:

public T GetItemAsync(string id)
{
    IQueryable<T> queryable = container.GetItemLinqQueryable<T>(true);
    queryable = queryable.Where<T>(item => item.Id == id);
    return queryable.ToArray().FirstOrDefault();
}

edited Sep 06 '20 at 12:57

answered Sep 06 '20 at 03:49

Vivek Sharma

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I do have partition key but that partition key value is not getting passed as an input. – DealZaap India Sep 06 '20 at 10:45
Updated the answer, what I meant was you don't have the partition key value to use for the operation. – Vivek Sharma Sep 06 '20 at 12:59
I have two search fields. ie, ID and Name. Is it advisable to create two container? – DealZaap India Sep 06 '20 at 16:46
If I am not giving patrician key then cost will increase? – DealZaap India Sep 06 '20 at 17:27
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If you are not providing the partition key in a search query, all partitions have to be searched, so the RUs will be higher. Please accept the answer if it solves the question. – Vivek Sharma Sep 06 '20 at 17:52
1

Thanks for your response. the method is good. Is there any way to asynchronous method to fetch in linq? – DealZaap India Sep 06 '20 at 21:49

score 0 · Answer 2 · answered Sep 06 '20 at 21:28

0

If you only have the id for the item and this is a high volume query, you may want to explore a new partition strategy for this container. But if there are also a high volume of reads that do use category, you could look at using change feed to keep two copies of the data and find another property that can be used as it's partition key. If id is globally unique in your application, then this could be used as well.

answered Sep 06 '20 at 21:28

Mark Brown

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Thanks for your reply. i Have below fields ID, Name, Category and Cost columns. My search will be mostly in ID and another search in Name.Is that ok to create two container one with ID and one with Name as partitions? – DealZaap India Sep 06 '20 at 22:45
You want to optimize around your high volume queries such that you are as efficient as possible. So knowing how many operations or queries you will run over say per second, minute, hour, etc. is important in this type of database. I would read this article and follow the steps it takes to get to its most optimal design [How to model and partition data on Azure Cosmos DB using a real-world example](https://learn.microsoft.com/en-us/azure/cosmos-db/how-to-model-partition-example) – Mark Brown Sep 07 '20 at 15:06

score 0 · Answer 3 · answered Aug 03 '23 at 16:09

0

You could also pass PartitionKey.None as the second parameter.

private async Task<T> GetItem(string id)
{
           
    ItemResponse<T> response = await this.MainContainer.ReadItemAsync<T>(id, PartitionKey.None);
    return response.Resource;
}

answered Aug 03 '23 at 16:09

Papa Stahl

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ReadItemAsync Cosmos DB

3 Answers3