16.20 - Nonhashed Tables - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantageā„¢ Data Dictionary

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Published
March 2019
Language
English (United States)
Last Update
2019-05-03
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When a table is nonhashed, the rows of the table are not distributed using hash maps and are instead stored AMP-locally. For example, each row of the DBC.DatabaseSpace table keeps track of the space used locally by one AMP. Similarly, recovery tables only contain the information necessary to recover any activity or transaction that occurred on their own AMP.

Acctg and DatabaseSpace are allowed for SHOW TABLE, HELP, and so on, and these two tables can be queried if you have the privileges for executing the statement on the table. Note that SHOW TABLE and HELP INDEX indicate these two tables have unique primary indexes even though they are actually nonhashed tables.

The other tables have special formats for their rows and cannot be queried and are not allowed for SHOW TABLE and so on (an error is returned that the table cannot be accessed).

The following table lists the nonhashed and NO FALLBACK Data Dictionary tables.

Nonhashed, NO FALLBACK Tables Description
Acctg Resource usage by Acct/User
ChangedRowJournal Down-AMP recovery journal
DatabaseSpace Database and table space accounting
LocalSessionStatusTable Last request status by AMP
LocalTransactionStatusTable Last transaction consensus status
OrdSysChngTable AMP recovery journal
RecoveryLockTable Recovery session locks
RecoveryPJTable Permanent journal recovery
SavedTransactionStatus AMP recovery table
SysRcvStatJournal Recovery, Reconfig, and startup info
TransientJournal Backout uncommitted transactions
UtilityLockJournalTable Host utility lock records