2.10.2 Locked resources

1

Single connection

This is a locked resource that is reserved when an application program connects to the HADB server or when one of the following commands is executed:

• adbimport command

• adbidxrebuild command

• adbgetcst command

• adbdbstatus command

• adbmodarea command

• adbexport command

• adbmergechunk command

• adbchgchunkcomment command

• adbchgchunkstatus command

• adbarchivechunk command

• adbunarchivechunk command

• adbreorgsystemdata command

• adbclientdefmang command

• adbsyndict command

• adbaudittrail command

• adbconvertaudittrailfile command

• adbmodbuff command

It is locked to prevent the adbmodarea command from executing concurrently with application programs or other commands.

2

Database access

This is a locked resource that is reserved at the following times:

1. When the maintenance processing of the updated-row columnizing facility is performed

2. When the transaction of an application program is executed

3. When a command that connects to the HADB server is executed

This locked resource is used to control locks so that the maintenance processing in 1 and the application program transaction in 2 do not occur concurrently. Locks are also controlled so that the maintenance processing in 1 and the command execution in 3 do not occur concurrently.

The control prevents the maintenance processing from starting while a transaction or command is running so that the processing performance of the transaction or command is not affected. If a transaction or command starts while maintenance processing is in progress, the maintenance processing is interrupted.

This locked resource is of no concern when disabling the updated-row columnizing facility.

For details about the commands that connect to the HADB server, see List of commands in List of Commands and Common Rules in the manual HADB Command Reference.

3

Dictionary

This is a locked resource that is reserved when a definition SQL statement is executed.

4

Pre-processing table

This is a locked resource that is reserved for each processing-target table at the following times:

• When a data manipulation SQL statement is preprocessed

• When a definition SQL statement is executed

• When a command is executed

5

DB area

Data DB area

This is a locked resource that is reserved when data in a data DB area is updated. It is locked to prevent the data in the same data DB area from being updated concurrently by an application and the command.

6

Dictionary DB area

This is a locked resource that is reserved at the following times:

• When a definition SQL statement is executed

• When the adbdbstatus command is executed

  However, even when the adbdbstatus command is executed, this locked resource is not reserved in the following cases:

  • When summary information for DB areas is output

  • When information is output by specifying the --shared-lock option

  • When information about the need for reorganization is output

7

System-table DB area

This is a locked resource that is reserved when data in a system-table DB area is accessed.

8

Table

Processing-target table

This is a locked resource that is reserved when the table to be processed is accessed.

9

Dictionary table

This is a locked resource that is reserved when a dictionary table (base table) is accessed.

10

System table (cost information)

This is a locked resource that is reserved when a system table (base table) that stores cost information is accessed. The target system tables (base tables) are as follows:

• STATUS_TABLES

• STATUS_COLUMNS

• STATUS_INDEXES

11

System table (chunk information)

This is a locked resource that is reserved when a system table (base table) that stores chunk information is accessed. The target system table (base table) is STATUS_CHUNKS.

12

System table (synonym dictionary information)

This is a locked resource that is reserved when a system table (base table) that stores synonym dictionary information is accessed. The target system table (base table) is STATUS_SYNONYM_DICTIONARIES.