plz explain parlla distribution and subtable concept in teradata
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Answer / karthik
parlla distribution:
This is the key concept of Teradata storing data in parallel, as it uses PI to store data, data is is stored parallel across the AMP's available.
Sub table: This table is created when a Unique secondary Index is created on the table, it will have rowid,data and hash value for the data. It is used to fetch the data using secondary index.
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Answer / yuvaevergreen
Parallel distribution: TD stores the data uniformly. Ideally, every amp should have equal no of rows from each table in vdisks.Based on the primary index, the distribution of data would be uniform on amps.
Sub table: It is used for secondary indexes and stored in amp(s).
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Answer / tdguy
Parallel distribution - Due to "shared nothing"
architecture, TD distributes and fetches the data in
parallel. Mainly because of AMP,PE and BYNET.
Subtables - These are created and used by TD, when the
secondary indexes come into picture.
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