In that case, while it was important to have a maximum of 10 results per page, it was also totally fine if there were fewer than 10 results. In the earlier Bing search example, the server returned 10 results per page. Many applications want to obtain an exact number of query results. Retrieving an exact number of query results Query, requestOptions: new QueryRequestOptions QueryDefinition query = new QueryDefinition(sqlQuery) įeedIterator resultSetIterator = ( Here’s an example: string sqlQuery = "SELECT TOP 20 * FROM c WHERE c.Item = 'shirt' AND c.Price > 75" If the query engine can return more results in each page, the query will require fewer round trips. With that default setting, queries are limited to returning 100 items per query page, regardless of whether the query is close to hitting the 4 MB limit per page limit or 5 second query execution limit. In most Azure Cosmos DB SDK versions, MaxItemCount defaults to 100. In this case, you should set MaxItemCount to -1 in your QueryOptions. The best way to do this is by minimizing the number of round trips that your application needs to make to Azure Cosmos DB. In some cases, you might want your query to return as much data as it can, as quickly as possible. Getting query results as quickly as possible Here’s how to do pagination with continuation tokens. You can limit continuation token size if needed, but we recommend keeping it as high as your application allows. A continuation token is a string (up to 16 KB) that the query engine can use to continue the query without having to repeat previous executions leading up to that point. If you want to stop your query and resume it later, you can extract a continuation token. Including a while loop is essential here, allowing the query to keep running until there are no more results. The Azure Cosmos DB SDK does most of the work for you. Here’s a query pagination example using the. Your code should always be able to handle the case where query results span multiple pages. The query engine may also split up results due to throttling. This is common for cross-partition queries, where you’ll occasionally get an empty page of results returned if there aren’t results from all physical partitions. There are also cases where the query engine returns results in multiple pages because it’s better for query performance. This is configurable with the MaxItemCount. Usability – Many applications can only handle a certain number of results back at once from Azure Cosmos DB.Even if you run a query and results aren’t available yet, you will always get a response back from Azure Cosmos DB after 5 seconds. Execution time – Every query execution is capped at 5 seconds.Data volume – Each page of query results is capped at 4 MB.In Azure Cosmos DB, there are similar reasons why queries can be split up into multiple pages of results: Even if we could return all 61.8 million results at once, the user would have a more difficult time digesting it. Usability – It’s easiest for the user to read through a small set of results at a time.In general, most users expect a web page to return data within a second or less. Execution time – Users are only willing to wait a short amount of time for data.Returning the full 61.8 million results would take too many resources. Data volume – There’s a finite amount of data that the server can return back to my web browser.Why is it beneficial to break up the results into multiple pages? There are a few reasons: Only 10 results are shown on the first page, but you can select to go to a later page if you want more results: Here’s an Internet search that returns 61.8 million results: Let’s start by taking a look an example of pagination outside of databases. While it’s important to understand how query pagination works in Azure Cosmos DB, it’s not a concept that’s unique to databases. Pagination of query results is done to divide a large volume of data across many small pages or handle a long-running query. In this post, we’ll take a look at tips for query pagination in Azure Cosmos DB.
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