15.00 - BLOCKERS - Teradata Database

Teradata Database Utilities

Product
Teradata Database
Release Number
15.00
Content Type
Configuration
Publication ID
B035-1102-015K
Language
English (United States)
Last Update
2018-09-25

BLOCKERS

Purpose  

The BLOCKERS command identifies blocked transactions and the transactions that are blocking them.

Syntax  

 

Syntax element...

Specifies...

ProcId

the virtual processor number of the parsing engine processor handling the transaction.

Since virtual processor numbers are designated as integer numbers, the corresponding value for this option normally is specified in decimal notation.

This number is the first component of a transaction ID.

Uniq1

a value that is normally specified as four hexadecimal digits.

This value is the second component of a transaction ID.

Uniq2

a value that is normally specified as four hexadecimal digits.

This value is the third component of a transaction ID.

ALL

that all blocked transactions and their corresponding blocker transactions will be considered.

ALL is the default if you do not specify a transaction ID.

LIMIT

the number of blocker transactions to consider for a blocked transaction.

NUMBER

the desired limiting value.

NONE

that all blocker transactions for a blocked transaction are considered.

Specifying NONE corresponds to specifying zero for Number.

Note: Together, ProcId, Uniq1, and Uniq2 identify a transaction ID.

Usage Notes

A transaction is an internal database concept. A transaction can have more than one blocking transaction. For example, a transaction can have five lock requests, and five transactions can block those same lock requests. In other words, if you have five tables, then conceivably, five other transactions can have the locks on those same five tables.

The following table shows the components of BLOCKERS command output.

 

Component....

Includes the...

Number of Blocked Trans displayed

total number of both blocked and blocker transactions.

Blocked Trans

number of the blocked transaction and the following information:

  • Number of blockers displays
  • Specifies blocker entry count.

  • Number of blockers exists
  • Specifies actual blocker count.

    Blocker Trans

    number of blocking transactions and the following information:

  • Lock mode
  • Specifies a type of lock mode:

  • Access
  • Read
  • Write
  • Exclusive
  • Lock status
  • Specifies a type of status of the lock request.

    Granted

  • Lock objectType
  • Specifies a type of object that is locked:

  • Database
  • Table
  • Rowrange
  • Rowhash
  • Lock objectID
  • Specifies an ID of the locked object and might include the following:

  • Database ID
  • Database Name
  • Table ID
  • Table Name
  • RowHashS
  • RowHashE
  • Note: If the lock objectType is Rowhash, only RowHashS is displayed; if the Lock objectType is RowRange, both RowHashS and RowHashE is displayed. RowHashS and RowHashE are the lower- and upper-bound levels of the RowHash range, respectively.

    Example  

    The following example shows one lock entry on AMP 0:

    > blockers LIMIT 1
    blockers LIMIT 1
    - The following amps are available:
        0     1     2
    Which amp(s) do you want to request on
    (S=Sampline/A=all/C=cancel/Q=quit):
    > 0
    0

    ---------------- AMP 0 REPORTS A LOCK ENTRIES ----------------
    Number of Blocked Trans displayed :      1
    =========================================
    Blocked Trans “ 16383 00001354
       Number of blockers displays :       1
       Number of blockers exists   :       1
       Blocker Trans : 16383 00001324
               lock mode       : Exclusive
               lock status     : Granted
               lock objectType : Table
               lock objectID   : DBID       : 00000428
                               : DBNAME     : STAFF
                               : TableID    : 00000519,0000
                               : TableName  : EMPLOYEE
                               : RowHashS   : 00000000
                               : RowHashE   : 00000000