As any experienced Teradata DBA will tell you, some tables in the Teradata dictionary (DBC) need housekeeping. But some customer sites that I have worked with ignore table DBC.AccessRights. If you have ever analyzed this table on a Teradata system, you will almost certainly spot two things very quickly. For a non-history table, it can

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Skewing is one of the biggest problems on a Teradata system because it harms performance. If a table has a high skew factor, not all AMPs are uniformly employed for queries on this table. This not only hurts this one query but on the entire system. The following happens in detail: Skew leads to low

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Dealing with data skew can be considered a principal activity in Teradata performance optimization. Although skew on table level usually can be avoided by choosing a proper Primary Index, skew arising during query execution is often a major issue (so-called spool skew). Spool skew is often emerging when joining tables (or spools). On a typical Teradata

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Anyone working with Teradata experiences sooner or later how the Impact of Skewing on Teradata impairs query run times. However, I assume only a few of us know exactly the order of magnitude of influence we have to expect. Let me, therefore, find some key figures which are helpful in getting the big picture.  That

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