Unity @xplain | Teradata Unity - 17.00 - Unity @xplain - Continuous Availability - Teradata Unity

Teradata® Unity™ User Guide

Product
Continuous Availability
Teradata Unity
Release Number
17.00
Published
September 2020
Language
English (United States)
Last Update
2020-09-15
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The Unity @xplain feature provides information about an executed query. The output of a SQL statement prefixed with @xplain returns the following result sets.
The output of a query prefixed with @xplain(#) returns only the specified result set.

Resultant Query / Rewrite Conditions

The resultant query result set provides the query after all rewrite rules have been applied.
 *** Query completed. One row found. One column returned.
 *** Total elapsed time was 1 second.

Resultant Query
-------------------------------
INS t0 SEL TOP 1 * FROM v0;
Column Details Possible Values
Resultant Query The query processed by Unity once all rewrite rules have been applied. The query as processed by Unity

Parsing Details

The parsing details result set provides the overall query details from the Unity parser.
 *** Query completed. One row found. 4 columns returned.
Parse Status  Query Class  Primary Table  Query Type
------------  -----------  -------------  ----------
successful    Insert       -              Write               -
Column Details Possible Values
Parse Status Indicates whether the parsing was successful Successful
Query Class Displays the statement type of the query Any valid statement type
Primary Table Name of the target table for single-table queries Name of the primary table, or "-" if unknown
Query Type Identify whether the query is a read or write operation read, write

Unflattened Object Details

The unflattened object details result set contains the list of objects being directly referenced by the query.
 *** Query completed. 2 rows found. 5 columns returned.
Object Type Access Dictionary ID Name Full Name
----------- ------ ------------- ---- ---------
view        read            1003 v0   db0.v0
table       write           1001 t0   db0.t0
Column Details Possible Values
Object Type The type of object table, view, macro, function, procedure, trigger, reference, UDT, other
Access The type of access read, write, call
Dictionary ID The Unity dictionary ID for the object Valid dictionary ID
Name Unqualified object name Name of object
Full Name Fully qualified object name Name of object, including database name

Flattened Object Details

The flattened object details result set contains the list of object and tables being accessed by the query once all views/macros/procedures are expanded.
 *** Query completed. 3 rows found. 4 columns returned.
   Table ID Name Full Name Access
----------- ---- --------- ------
       1002 t1   db0.t1    read
       1003 v0   db0.v0    read
       1001 t0   db0.t0    write
Column Details Possible Values
Table ID The Unity dictionary ID for the object Valid dictionary ID
Name Unqualified object name Name of object
Full Name Fully qualified object name Name of object, including database name
Access The type of access read, write

Lock List

The lock list result set contains the list and type of locks obtained by Unity for the query.
 *** Query completed. 3 rows found. 6 columns returned.
    Lock ID Full Name Type  Scope            Level Row Hash
----------- --------- ----- ---------------- ----- ----------------
       1001 db0.t0    write transaction      table -
       1002 db0.t1    read  transaction      table -
       1003 db0.v0    read  transaction      table -
Column Details Possible Values
Lock ID The Unity dictionary ID for the object Valid dictionary ID
Full Name Fully qualified object name Name of object, including database name
Type The lock type access, read, write, write escalate, exclusive, exclusive escalate
Scope The lock scope transaction
Level The lock level table, row
Row Hash For row lock, the corresponding row hash for the lock. Row hash value, or "-" for table lock

Replication Type

The replication type result set provides details on whether a query will be SQL replicated or CDM replicated.
 *** Query completed. One row found. One column returned.
Replication Type
---------------------------------------------------------------------------------------
Write request CDM replicated because query uses a TOP clause in a write query
Column Details Possible Values
Replication Type Provides details on whether the query is a read/write/DDL query, whether it will be SQL or CDM replicated, and details for the replication choice Text detailing the replication type