15th June 2024

Oracle Database 20C – Oracle Blockchain Table

Blockchain is a technology that is actively used today. Unlike other structures, the Oracle Blockchain table can be used for blockchain applications where the central authority is Oracle Database. In this structure, being able to decide who will join the blockchain network provides institutions and organizations with more customizability and better control. All participants joining this network with the permissions granted must have privileges to add data to the Blockchain tables. Contents are defined and managed by Blockchain applications. This structure provides higher efficiency and lower transactions than non-blockchain architectures.

Note: Oracle Blockchain table is currently used only on Oracle Cloud.

It consists of rows added one after the other, like in classic Blockchain tables. On the blockchain, every row depends on the previous row, except for the first row. However, the rows in the blockchain tables are protected from manipulation compared to a conventional OLTP table. Each row is clipped with a dependent hash to the data in the row before it. If the data in a row changes, the HASH value of that row also changes. This also affects the HASH values ​​of the lines that follow.

Note: BlockChain tables can be recommended when the immutability of the data is critical to your centralized applications and you want to protect past transactions from manipulation.

Benefits of Blockchain Tables

  • Provides transparent protection against manipulation by other participants participating in the blockchain network.
  • Rows in the blockchain table are detected by verifying with HASH.
  • Since it is part of the Oracle Database architecture, a new infrastructure is not required.
  • It allows you to preserve the existing architecture and programming model. In this way, existing databases can be made more secure.
  • It is easier to use compared to the distributed Blockchain architecture.
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Blockchain tables are additional tables that are allowed only insertions. Deletion of rows is prohibited and restricted depending on the time. Rows in blockchain tables are made resistant to manipulation with special sorting and chain algorithms. Users can verify that the rows have not been changed. Hash values that are part of row metadata can be used to validate other rows.



Blockchain tables can be indexed and partitioned as in the classical database architecture. It can also be used with the paintings in classical architecture.

Blockchain tables classic database architecture
Blockchain tables classic database architecture


Rows in blockchain tables can be signed by users. You can see a sample Blockchain table creation method below.

SQL> CREATE BLOCKCHAIN TABLE ledger_emp (employee_id NUMBER, salary NUMBER)
                     NO DROP UNTIL 31 DAYS IDLE
                     NO DELETE LOCKED
                     HASHING USING "SHA2_512" VERSION "v1";

Table created.

Blockchain table
Blockchain table


Adding data to a created table.

SQL> INSERT INTO ledger_emp VALUES (106,12000);

1 row created.


Commit complete.

Adding data to the table
Adding data to the table

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