SQL/MX 2.x Reference Manual (H06.04+)

Introduction
HP NonStop SQL/MX Reference Manual—540440-003
1-16
Concurrency
These tables describe interactions between SQL/MX operations:
Table 1-1 on page 1-16 compares operations with access modes and lists DDL and
Utility operations you can start while DML operations are in progress.
Table 1-2 compares DDL and utility operations with DML operations and shows DDL
operations you can start while DML operations are in progress:
Table 1-1. Concurrent DDL/Utility Operation and File Access Modes
Access Mode
DDL Operations
You Can Start
READ
UNCOMMITTED
READ
COMMITTED STABLE SERIALIZABLE
ALTER INDEX Allowed Allowed Allowed Allowed
ALTER TABLE
attributes
Allowed
* Allowed* Waits Waits
* DDL operation aborts the DML operation
Table 1-2. Concurrent DDL/Utility and DML Operations
DML Operation in Progress
DDL Operations You Can
Start
SELECT
UNCOMMITTED
SELECT
SHARE
SELECT
EXCLUSIVE
UPDATE/
INSERT/
DELETE
ALTER INDEX Allowed
*
Allowed Allowed Allowed
ALTER TABLE attributes Allowed
*
Allowed Allowed Allowed
ALTER TABLE other Allowed
*
Waits Waits Waits
CREATE INDEX with
POPULATE
Allowed
*
Allowed Waits Waits
CREATE INDEX NO
POPULATE
Allowed Allowed Allowed Allowed
CREATE TRIGGER subject
table
Allowed Allowed Waits Waits
CREATE TRIGGER
referenced table
Allowed Allowed Allowed Allowed
CREATE VIEW Allowed Allowed Allowed Allowed
GRANT Allowed
*
Waits Waits Waits
MODIFY online operations Allowed
*
Allowed
**
Allowed
**
Allowed
**
MODIFY offline operations
***
Allowed
*
Allowed
**
Allowed
**
Waits
POPULATE INDEX Allowed
*
Allowed
**
Allowed
**
Waits