Transaction Properties#
AUTO_COMMIT#
Data Type#
Unsigned Integer
Default Value#
1
Attributes#
Read-Write, Single Value
Range#
[0, 1]
Description#
This property determines whether to handle each individual SQL statement as a separate transaction and commit it when SQL statements are executed in a session. A value of 1 indicates auto-commit mode, while a value of 0 indicates non-autocommit mode. When using non-autocommit mode, the client application must explicitly indicate the beginning and end of a transaction.
Even if this value is set to 1, indicating auto-commit, when the server is started, this property can be changed for individual sessions. For example, if ALTER SESSION SET AUTOCOMMIT = FALSE (non-autocommit) is executed from a client, the user must explicitly specify whether to commit or rollback any transactions that occur for the remainder of the session.
This property can be changed using the ALTER SYSTEM statement while Altibase is running.
ISOLATION_LEVEL#
Data Type#
Unsigned Integer
Default Value#
0
Attributes#
Read-Only, Single Value
Range#
[0, 3]
Description#
This property specifies the transaction isolation level. When a single transaction searches the same table multiple times, the result varies depending on the isolation level.
For more information about transaction isolation levels, please refer to the Administrator's Manual.
| Isolation Level | Characteristics |
|---|---|
| 0 (Committed Read) | This is the default mode of Altibase. This isolation level guarantees that previously read data that have been modified by another transaction will reflect the changes of that other transaction. When a SELECT transaction reads data one time and then reads the data again, if another transaction simultaneously executes and commits an INSERT or DELETE statement, due to this change, it is possible for a new row to be found, or for a previously found row to have disappeared. |
| 1 (Repeatable Read) | This isolation level guarantees that the contents of a row will be the same upon repeated reads by the same transaction.This isolation level places a lock on a row once it has been read. Therefore, when the table is subsequently read, previously read rows will not change or disappear, but it is possible for new rows to appear. |
| 2 (No Phantom) | This isolation level guarantees identical results for repeated reads. |
TRANSACTION_TABLE_SIZE (Unit: Transaction count)#
Data Type#
Unsigned Integer
Default Value#
1024
Attributes#
Read-Only, Single Value
Range#
[16,16384]
Description#
The number of transactions which can be simultaneously created during the Altibase service is specifiable when creating a database, and memory for such process is allocated in advance.
This property should increase or decrease the value by 2n and the database must be created again when decreasing the value.