Because Teradata Database hash functions are formally mature and mathematically sound, rows with unique primary indexes are always distributed in a uniformly random fashion across the AMPs, even when there is a natural clustering of key values. As can be seen it is a single-AMP retrieval and the optimizer is using the unique primary index to access the row. The HASHAMP function returns the identification number of the primary AMP for any Hash Bucket number. As mentioned previously, Teradata uses a hashing algorithm to determine which AMP is responsible for a data row's storage and retrieval. It does output conversion and formatting C. It does the physical work associated with generating an answer set D. It develops the least expensive plan to return the requested response set ANS:: A,B,C. In that sense, each AMP was a node. The hashing functions introduced in this section provide information pertaining to the selection of the AMP where each individual row is stored. The function returns the AMP number which will hold the table row in its vdisk. Each AMP in Teradata has its own disk attached to it. In Teradata V1, the Access Module Processor (AMP) was the physical processing unit for all the Teradata database functions. However AMP worker tasks that invoke the function will be held for the period of time that a table operator executes externally. Functions provide a single result by accepting input arguments and returning an output value. When no value is passed to the HASHAMP function, it returns a number that is one less than the number of AMPs in the current system configuration A. It has access to a single vdik B. SQL Functions SQL functions return information about some aspect of the database, depending on the arguments specified at the time the function is invoked. 1) First, we do a single-AMP RETRIEVE step from TDUSER.employee by way of the unique primary index "TDUSER.employee.EmployeeNo = 101" with no residual conditions. Aggregate functions operate on a group of rows and return a single numeric value in the result table for each group. This method is much faster than randomized allocation, especially for large sample sizes. HASHAMP function in Teradata. 14. Each AMP then contained its own microprocessor, disk drive, file system, database software (Database Manager), Teradata Operating System (TOS), and YNET interface. This means that the requested rows are allocated across the AMPs as a function of the number of rows on each AMP. The concepts of protected mode and unprotected mode discussed earlier work the same for table functions and table operators. A. What is the function of an AMP? If you drop a UDF and then recreate it to return a different type, Teradata Database ignores the existing statistics for that function during optimization. Some SQL functions, referred to as niladic functions… Which feature is unique to Teradata? 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