Sybase 12.4.2 User Manual

CHAPTER 8    Transactions and Versioning

Cannot perform DDL command now as a DDL command is already in progress.

If a 

CREATE DBSPACE

 or 

DROP DBSPACE

 command is in progress, and a user 

explicitly issues a 

CHECKPOINT

 command, the checkpoint fails with the 

message:

Run time SQL Error

If a 

CHECKPOINT

 command is in progress, a user who issues a 

CREATE 

DBSPACE

 or 

DROP DBSPACE

 command gets the following message:

Cannot perform requested command as there is a 

CHECKPOINT command in progress.

A user who issues 

CREATE DBSPACE

 during a drop gets the message

Cannot perform requested command as there is a 

DROP DBSPACE command in progress.

A user who issues 

DROP DBSPACE

 during a create gets the message:

Cannot perform requested command as there is a 

CREATE DBSPACE command in progress.

See “Versioning of temporary tables” for special rules regarding temporary 
tables.

When one transaction issues a DDL command on a given table or index, any 
other transaction that began before the DDL transaction commits, and that tries 
to access that table, receives an error.

When this error occurs, any additional attempts to read or write to the table in 
the current transaction will fail. 

If a transaction modifies the definition of a table that is part of a join index, it 
locks every table with any columns that are joined in that index. This result 
occurs whether or not the particular columns in the original write transaction 
are being joined. 

Concurrency rules for 
index creation 
commands

There is an exception to these rules for index creation commands. 

CREATE 

INDEX

 and 

CREATE JOIN INDEX

 can occur concurrently with a 

SELECT

 on the 

table(s) affected by the index creation. Adaptive Server IQ prevents use of the 
new index or join index until the transaction creating the index commits.