In Teradata V1, the Access Module Processor (AMP) was the physical processing unit for all the Teradata database functions. 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 It has access to a single vdik B. The function returns the AMP number which will hold the table row in its vdisk. HASHAMP function in Teradata. 13. Each AMP then contained its own microprocessor, disk drive, file system, database software (Database Manager), Teradata Operating System (TOS), and YNET interface. SQL Functions SQL functions return information about some aspect of the database, depending on the arguments specified at the time the function is invoked. 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. As mentioned previously, Teradata uses a hashing algorithm to determine which AMP is responsible for a data row's storage and retrieval. The concepts of protected mode and unprotected mode discussed earlier work the same for table functions and table operators. Each AMP in Teradata has its own disk attached to it. Also it performs any data conversion,aggregation,sorting,manipulate the disk sub system in the multi tasking and possibly parallel processing in the environment of the Teradata database. This means that the requested rows are allocated across the AMPs as a function of the number of rows on each AMP. The HASHAMP function returns the identification number of the primary AMP for any Hash Bucket number. Aggregate Functions Aggregate functions are typically used in arithmetic expressions. This method is much faster than randomized allocation, especially for large sample sizes. As can be seen it is a single-AMP retrieval and the optimizer is using the unique primary index to access the row. However AMP worker tasks that invoke the function will be held for the period of time that a table operator executes externally. 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. A. 14. Some SQL functions, referred to as niladic functions… The SAMPLE clause is a Teradata extension to the ANSI SQL:2011 standard. A. In that sense, each AMP was a node. Which feature is unique to Teradata? Functions provide a single result by accepting input arguments and returning an output value. Aggregate functions operate on a group of rows and return a single numeric value in the result table for each group. 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. 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. The hashing functions introduced in this section provide information pertaining to the selection of the AMP where each individual row is stored. Accepting input arguments and returning an output value rows are allocated across the AMPs a... Amp is responsible for a data row 's storage and retrieval primary index to Access the row across the as. The HASHAMP function returns the identification number of rows and return a single numeric in. 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