# Reads Execution (Continued)
__*Cop Task*__
__*Root Task*__

![left](./student-guide/diagram/ExecuteandRead03_aa_002_20220512.png)

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Finally, the query results are return to the TiDB Server, but calculation request that can be pushed to TiKV currently include TableScan, IndexScan, Selection, TopN, Limit, and PartialAggregation. Other more complex operators still require a single TiDB Processing takes place on the server. Therefore, it will be summarized in TiDB Server. Once the summary is complete, the result set is formed. If it is a query operation, the result set (including the Field list, row data) is written back to the client.

It should be mentioned here that in the read execution (B), some operators are pushed down to TiKV for execution, and the other part is finally summarized in TiDB Server. As a result, there are two computational tasks (Tasks), which are Cop Task and Root Task, which are defined as follows:

- CopTask is a physical plan that needs to be pushed down to the storage engine (TiKV) for computation. Each TiKV node that receives the request does the same operation.

- RootTask is the part of the physical plan that is calculated in TiDB.