NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
C-61
Summary of Concurrent DDL and DML Operations
•
Summary of Concurrent DDL and DML Operations shows DDL operations that
limit (or are limited by) DML operations. For DDL operations that occur in two
phases, the table shows both scan and update (change timestamp) phases.
•
ALTER Operation Effects on Timestamps shows the forms of the ALTER statement
that change the timestamp of an object. The concurrency of an ALTER operation
depends on whether ALTER changes a timestamp.
•
Limits on Concurrent Utility and DML Operations shows utility operations that
limit concurrency.
Summary of Concurrent DDL and DML Operations
DML Operation in Progress
DDL Operations You
Can Start
SELECT
BROWSE
SELECT
SHARED
SELECT
EXCLUSIVE
DELETE/INSERT
UPDATE
ALTER
WITH SHARED
ACCESS
A A Wait Wait
Timestamp change A
1
Wait Wait Wait
No timestamp change A A A Wait
CREATE
CONSTRAINT
A
1
Wait Wait Wait
CREATE INDEX A
1
A Wait Wait
WITH SHARED
ACCESS
A A Wait Wait
UPDATE STATISTICS A
1
Wait Wait Wait
UPDATE STATISTICS
Scan phase A A Wait Wait
Change timestamp A
1
Wait Wait Wait
A Allowed
Wait Started operation waits for the operation in progress to complete. The waiting operation might also time
out.
1
DDL operation aborts the DML operation
2
Allowed except during commit phase