R:BASE 11 Help

Zoom Window Out
Larger Text | Smaller Text
Hide Page Header
Show Expanding Text
Printable Version
Save Permalink URL

Navigation: Reference Index > Multi-User Guide > Multi-User Concurrency Settings

Table Locks

The below table describes the automatic concurrency control and locks used in multi-user mode and the commands that initiate them. Operations that only view data or the database structure are not affected by concurrency control or locking.

Type of Lock	Command	Description
Concurrency Control	EDIT EDIT USING ENTER	Prevents one user from accidentally overwriting another user's changes. These commands can access the same table simultaneously.
Row Lock	DELETE ROWS ENTER form INSERT values LOAD FROM filespec UPDATE	When SET ROWLOCKS is on, a lock is only applied to a row. When off, a table lock is in effect.
Table Lock	BACKUP* DROP RULES FORMS GRANT INSERT subselect RBLABELS LOAD from filespec REPORTS RESTORE REVOKE RULES SET LOCK ON UNLOAD*	Must wait for commands that obtain table and database locks. Once obtained, this lock excludes all other concurrency control and locking until these commands have finished.
Full Database Lock	BACKUP ALL RELOAD UNLOAD ALL	All tables in the database are locked.
Database Schema Lock	ALTER TABLE CREATE SCHEMA CREATE TABLE CREATE VIEW CREATE INDEX DROP INDEX DROP COLUMN DROP TABLE DROP VIEW INTERSECT JOIN PROJECT RENAME SUBTRACT UNION	Engages a full database lock preventing schema modifications, then releases the schema lock remaining in table lock.
Cursor Lock	OPEN cursorname	Stops database schema commands but allows table locks; acts as a table lock.

*A table lock is placed only if one table is unloaded. A database lock is placed if more than one table is unloaded.

The below table shows what happens when different commands try to access a table or database already being used by another command. The columns represent the type of control or lock already placed on the table or database. Each row has a heading with the name of the control or lock needed by the command trying to gain access to a table or database.

	Concurrency Control	Cursor Lock	Row Lock	Table Lock	Database Lock	Schema Lock
Cursor Lock	Access	Access	Access	Wait	Quit	Wait
Row Lock	Access	Access	Access	Wait	Quit	Wait
Concurrency Control	Access	Access	Access	Wait	Quit	Wait
Table Lock	Wait	Wait	Wait	Wait	Quit	Wait
Database Lock	Wait	Wait	Wait	Wait	Quit	Wait
Schema Lock	Wait	Wait	Wait	Wait	Quit	Wait

Please enable JavaScript to view this site.

R:BASE 11 Help