We return to the discussion on Teradata.
Teradata has an admin user called DBC. This comes with each system.
User DBC has always been at the top of the Teradata hierarchy. An admin user is explicitly provisioned to facilitate addition of other users. Some space is reserved for user DBA. Space on the disk for each AMP is divided into PERM space and SPOOL space. PERM space is reserved for tables. Secondary indexes, join indexes and permanent journals are also stored in PERM. SPOOL is used for user queries and answer sets.
Disks are not shared between AMPs.
Every user is assigned spool space so they can submit SQL and retrieve answer sets. If the user exceeds this space, the query is aborted.
The spool limits are so that long queries can be terminated and individual users don't hog the system.
Each user's spool limit is actually done per AMP. If the space is exceeded on any AMP, the query is aborted.
The DBC data dictionary shows how much space is reserved. When the space per AMP shows skew, typically this is due to NULL data.
The access is usually granted to users to read views which are in turn granted access to read tables.
A database or a user can be assigned PERM space and spool space.
Objects that take up PERM space include Table rows, fallback tables, secondary index subtables, stored procedures, user defined functions, permanent journals etc.
Access rights can be granted to user. There are three types of access rights:
automatic rights which are default and granted to owners of created tables.
Implicit rights which are ownership rights and are implicit to parents and anybody above in the user hierarchy,
Explicit rights which are privileges a user explicitly grants to another user with the grant to statement.
These rights may be explicitly removed
Profiles and roles are different. Profiles are for people and roles are for rights. A profile can be assigned to a group of users so that they operate under a common set of attributes. for example a setting the can be used to override that of the users.
Account strings can be expanded to include logon time, date, hour, session ID, number etc.
The Teradata Active System Management TASM controls the query traffic. User accounts are given priority and rules setup to control system resources.
Secondary index can be created. If it is unique, it can be hashed.
A USI is a two AMP operation because the first AMP is assigned to read the subtable and the second the base table. Records are looked up in both via binary searches.
A non-unique secondary Index table is AMP_Local.
A value ordered NUSI can also be created.
Teradata has an admin user called DBC. This comes with each system.
User DBC has always been at the top of the Teradata hierarchy. An admin user is explicitly provisioned to facilitate addition of other users. Some space is reserved for user DBA. Space on the disk for each AMP is divided into PERM space and SPOOL space. PERM space is reserved for tables. Secondary indexes, join indexes and permanent journals are also stored in PERM. SPOOL is used for user queries and answer sets.
Disks are not shared between AMPs.
Every user is assigned spool space so they can submit SQL and retrieve answer sets. If the user exceeds this space, the query is aborted.
The spool limits are so that long queries can be terminated and individual users don't hog the system.
Each user's spool limit is actually done per AMP. If the space is exceeded on any AMP, the query is aborted.
The DBC data dictionary shows how much space is reserved. When the space per AMP shows skew, typically this is due to NULL data.
The access is usually granted to users to read views which are in turn granted access to read tables.
A database or a user can be assigned PERM space and spool space.
Objects that take up PERM space include Table rows, fallback tables, secondary index subtables, stored procedures, user defined functions, permanent journals etc.
Access rights can be granted to user. There are three types of access rights:
automatic rights which are default and granted to owners of created tables.
Implicit rights which are ownership rights and are implicit to parents and anybody above in the user hierarchy,
Explicit rights which are privileges a user explicitly grants to another user with the grant to statement.
These rights may be explicitly removed
Profiles and roles are different. Profiles are for people and roles are for rights. A profile can be assigned to a group of users so that they operate under a common set of attributes. for example a setting the can be used to override that of the users.
Account strings can be expanded to include logon time, date, hour, session ID, number etc.
The Teradata Active System Management TASM controls the query traffic. User accounts are given priority and rules setup to control system resources.
Secondary index can be created. If it is unique, it can be hashed.
A USI is a two AMP operation because the first AMP is assigned to read the subtable and the second the base table. Records are looked up in both via binary searches.
A non-unique secondary Index table is AMP_Local.
A value ordered NUSI can also be created.
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