C1 Command (Write a Checkpoint)

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# C1 Command (Write a Checkpoint)

This document covers the following topics:

- Function and Use

- Control Block

- Example

## Function and Use

The C1 command is used to request that a checkpoint be taken.

C1 commands are normally issued only by exclusive control update users who are not using ET Logic. Even if a C1 command is issued by an ET Logic user, it is not subject to ET Logic, which means that its effects will not be wiped out by a BT (backout transaction) command.

Adabas automatically executes a C1 command at the beginning of a user program in which exclusive file control updating has been requested.

The result of the C1 command is a checkpoint entry in the Adabas checkpoint table. This checkpoint entry contains the checkpoint identifier (the value provided by the user in the Command ID field), and the current data protection log and block number. This checkpoint entry may be used to restore the database (or certain files) to the status in effect at the time the checkpoint was taken. This may be necessary before a program that performs exclusive control updating can be rerun or restarted.

##### C1 Command, Procedure Flow

### Control Block

Field | Format |
--- | --- | ---
Call Type | B | F/U
Reserved (internal use) |  | -/-
Command Code | A | F/U
Command ID | B | F/U
File Number | B | F/U (1)
Response Code | B | F/A (1)
Additions 2 | A,B | -/A
Command Time | B | -/A
User Area |  | F/U

### Buffer Areas

Buffer |
--- | ---
Format Buffer | –/–
Record Buffer | –/–
Search Buffer | –/–
Value Buffer | –/–
ISN Buffer | –/–

> Formats:

>   A | alphanumeric
>   B | binary

> x/y before/after Adabas call - x and y can take the values:

>   A | Filled in by Adabas
>   F | To be filled in by User
>   U | Unchanged after Adabas call
>   - | Not used

>   (1) The meaning of this field depends on the value specified for "Call Type". See Calling Adabas, The Control Block for details.

## Control Block

> Command Code

>   C1

> Command ID

>   A non-blank, non-zero value must be entered in this field. This value will serve to identify the checkpoint taken. It is not necessary that each value provided for each checkpoint is unique.

>   A value of 'SYNx' must not be specified.

> Response Code

>   Adabas returns the response code for the command in this field. Response code 0 indicates that the command was executed successfully.

> Additions 2

>   For some response codes, Adabas returns detailed information in this field. See Adabas Messages And Codes for further information.

## Example

The user requests a checkpoint. The checkpoint is to be identified by the value USR4.

#### Control Block:

    Command Code          C1

    Command ID            USR4 (checkpoint identifier)

### On this page

- Function and Use
- Control Block
- Example