What do the various abbreviations in the DC001010 task stall MODE field mean?

Products

• IDMS
• IDMS - Database
• IDMS - ADS

Issue/Introduction

 For example, in message DC001010 V74 T64 TXNID:44756 PROG:LOCKTEST SUBSCHEMA:EMPSS01 MODE:X

What does MODE: X mean and where are these abbreviations documented in the IDMS manuals?

 

Environment

IDMS - All Supported Releases

Resolution

These two IDMS messages; DC001008 and DC001010 contain references to db-key modes. What do the MODE abbreviations mean and where are they documented in the IDMS manuals?

DC001010 V74 T64 TXNID:44756 PROG:LOCKTEST SUBSCHEMA:EMPSS01 MODE:X

When these messages refer to the <db-key mode>, they are actually referring to the locking mode in which the dbkey is held, i.e., the type lock placed on the dbkey.

These type of locks are documented in Administering IDMS Database, section Locking Within Central Version   The abbreviations related to DBKEY locks are:

S     = Share
X     = Exclusive
NL    = Null Lock

Mode: Share

Typically used to guarantee that no updates are made to data while a transaction is accessing it. A share lock is compatible with other share locks but not with exclusive locks. A share lock placed on an area implies a share lock on each record within the area.

Mode: Exclusive

Typically placed on a resource to protect transactions from accessing data that is being updated by the issuing transaction. An exclusive lock is incompatible with both share and other exclusive locks. An exclusive lock placed on an area implies an exclusive lock on all records within the area.

Mode: Null-lock

A null-lock is a special type of lock which is placed on a record to signify a notify lock and on an area to signify transient retrieval access. Null-locks provide no protection against concurrent access.