Access Module Processor (AMP) − AMPs, called as Virtual Processors (vprocs) are the one that
actually stores and retrieves the data
. AMPs receive the data and execution plan from Parsing Engine, performs any data type conversion, aggregation, filter, sorting and stores the data in the disks associated with them.
What is AMP CPU skew in Teradata?
CPU Skew – Percentage
representing how skewed a query is when comparing the hottest AMP CPU during the last sample period
to the average AMP CPU during the last sample period. 61.1% is quite a skewed query.
How many AMPs is my Teradata?
HASHAMP function in Teradata
The function returns the AMP number which will hold the table row in its vdisk. This AMP will be responsible for the portion of table rows which it stores in it vdisk. It takes
HASHBUCKET#
as the input and returns the AMP number.
What type of processing is occuring when updating a table where all AMPs are involved?
What type of processing is occurring when updating a table where all AMPs are involved? Options are :
row
.
What are the functions of parsing engine?
Interprets the SQL statement received from the application
. Verifies SQL requests for the proper syntax and evaluates them semantically. Consults the Data Dictionary to ensure that all objects exist and that the user has authority to access them.
How many AMPs is a Teradata node?
1 Answer. The number of AMPs per node is determined by the available CPU and IO. Usually it’s
approx. 1 AMP per logical CPU
and each AMP has assigned 2*2 mirrored (RAID1) disks (plus eventually a 1/4 of a SSD).
How do you reduce skew factor?
Skew factor can be reduced by
choosing more evenly distributed set of columns
. if your 2% is going to one amp then you can find out what distinguishs it in other columns from each other.
What is impact CPU in Teradata?
Impact CPU is
the CPU used on the hottest AMP multiplied by the number of AMPs involved in the query
. In other words, it’s the actual “impact” the system felt from running the query. If the Impact CPU is around 100x bigger than the Request CPU, then the query is highly skewed.
What is acceptable skew factor in Teradata?
A Skew factor of
30
means there’s about 40% more data on the max AMP compared to the average. This might still be acceptable (of course it depends), talk to your DBSa what they usually consider too big. On the other hand 98 means there’s 40 to 50 times more data on the max-AMP and that’s waaaay to much.
Do volatile tables use spool space?
A volatile table is a temporary table that is only held until the end of session. This is created by default in your “personal schema” and
consumes your spool space to maintain
.
How do I update a table in Teradata?
You can update columns in a table by
UPDATE command
. Examples: UPDATE tbl_emp SET emp_no=12345.
How do the virtual processors VProcs communicate with each other?
Teradata utilizes Parsing Engines (PE)
and Access Module Processors (AMPs)
in which they call VProcs. The VProcs get loaded inside the Nodes memory and then we connect this node via the BYNET with all the other nodes and now we are part of the Teradata warehouse. …
What are the components of Teradata?
The major components of Teradata are
Parsing Engine, BYNET and Access Module Processors (AMPs)
. The following diagram shows the high level architecture of a Teradata Node.
What are the features of Teradata Rdbms?
- 1) Linear Scalability.
- 2) Unlimited Parallelism.
- 3) Mature Optimizer.
- 4) Shared Nothing Architecture.
- 5) Connectivity.
- 6) Low TCO.
- 7) SQL.
- 8) Load & Unload utilities.
What is AMP SQL?
AMP, acronym
for “Access Module Processor
,” is the type of vproc (Virtual Processor) used to manage the database, handle file tasks and and manipulate the disk subsystem in the multi-tasking and possibly parallel-processing environment of the Teradata Database.
What is a skew factor?
Skew factor is
distribution of rows of a table among the
.
available no. of AMP’s
. If your table has a chance of using unique primary index,it.
