2.10.6 Dictionary tables and system tables locked when a database is referenced or updated

When an SQL statement or command is executed to reference or update a database, the dictionary tables (base tables) and system tables (base tables) are locked. The following two tables show the dictionary tables and system tables that are locked when a database is referenced or updated.

Table 2‒17: Dictionary tables and system tables locked when a database is referenced or updated (1)

Legend:

EX

The resource is locked in exclusive mode (EX).

SRW

The resource is locked in shared retrieval mode (SR). Note that if a transaction attempts to reserve a locked resource that has already been reserved by another transaction, the transaction waits until the resource becomes able to be reserved.

SR

The resource is locked in shared retrieval mode (SR).

●

The resource is locked in shared retrieval mode (SR) when any of the following objects are specified in the SQL statement. Note that if a transaction attempts to reserve a locked resource that has already been reserved by another transaction, the transaction waits until the resource becomes able to be reserved.

1. Table function derived table for which the ADB_AUDITREAD function is specified

2. SQL_AUDITS dictionary table

3. Viewed table defined by specifying in a CREATE VIEW statement a table function derived table that specifies the ADB_AUDITREAD function

4. Viewed table defined by specifying the SQL_AUDITS dictionary table in a CREATE VIEW statement

5. Viewed table that depends on the preceding viewed tables in the list (items 3 or 4)

Table 2‒18: Dictionary tables and system tables locked when a database is referenced or updated (2)

Legend:

SRW

The resource is locked in shared retrieval mode (SR). Note that if a transaction attempts to reserve a locked resource that has already been reserved by another transaction, the transaction waits until the resource becomes able to be reserved.

SR

The resource is locked in shared retrieval mode (SR).

SR/SUW

If the target resource is a table that is not to be manipulated by using an SQL statement or command, the resource is locked in shared retrieval mode (SR).

If the target resource is a table that is to be manipulated by using an SQL statement or command, the resource is locked in shared update mode (SU). Note that if a transaction attempts to reserve a locked resource that has already been reserved by another transaction, the transaction waits until the resource becomes able to be reserved.

-/SUW

If the target resource is a table that is not to be manipulated by using an SQL statement or command, the resource is not locked.

If the target resource is a table that is to be manipulated by using an SQL statement or command, the resource is locked in shared update mode (SU). Note that if a transaction attempts to reserve a resource that has already been reserved by another transaction, the transaction waits until the resource becomes able to be reserved.

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