Consideration before conversion

Overview

Before Migrating from ORACLE, you need to check the features which ALTIBASE HDB doesn't provide but ORACLE does.

Here 's a brief overview about the features those ALTIBASE HDB does not provide.

Object

Materialized View

ALTIBASE HDB does not provide Materilaized View functionality that ORACLE supports.

But, this functionality will be applied at ALTIBASE HDB V7.

Index Organized Table (IOT)

ALTIBASE HDB does not support Index Organized Table that ORACLE supports.

Cluster

ALTIBASE HDB does not support Cluster object.

Index

There're various index types which ORACLE supports, such as

• B-Tree Index
• Bitmap Index
• Function Based Index
• Application Domain Index
• R-tree Index (for spatial only)

ALTIBASE HDB supports only B-Tree index and R-Tree Index (Spatial Data only).

But, Among those indexes listed above, A Function Based Index functionality will be applied at ALTIBASE HDB V7.

CHECK constraint on Table

ALTIBASE HDB does not support CHECK constraint that checks column value whether those to insert are proper for this constraint.

But, this functionality will be provided at ALTIBASE HDB V7.

XML support

ALTIBASE HDB does not support XML types, and related functionality.

Development

Hierarchy Query

ALTIBASE HDB provides the limited functionality about hierarchy query. ALTIBASE HDB does not support following features those ORACLE provides

• CONNECT_BY_ISCYCLE pseudocolumn
• CONNECT_BY_ISLEAF pseudocolumn
• CONNECT_BY_ROOT operator
• SYS_CONNECT_BY_PATH function
• SIBLINGS in order by clause

But, At ALTIBASE HDB V7, The functionality of Hierarchical query will be enhanced.

Among of them described above, CONNECT_BY_ISCYCLE pseudocolumn, CONNECT_BY_ISLEAF pseudocolumn, SIBLINGS will be included in ALTIBASE HDB.

Analytic Functions

ALTIBASE HDB provides the limited functionality about analytic functions.

At the ALTIBASE HDB version 6, some of the  window functions, namely ranking functions,  those are added in a limited extent.

Those are DENSE_RANK(), RANK(), ROW_NUMBER() functions.

Updatable Join view

To use DML statement on View except SELECT statement is not allowed to use in ALTIBASE HDB. 

External Procedures

External procedure means that DBMS engine provides the way to adopt functions or procedures written in C/C++ or Java or any progammable lanuage.

But ALTIBASE HDB does not support this feature.

Package

ALTIBASE HDB does not provide Package.

But, this functionality will be adopted as a name of the Stored Package in psm at ALTIBASE HDB V7.

SQL resultset cache (Client side)

ALITBASE HDB does not provide SQL resultset cache function, namely the cache as a result of the query or function is stored in the client side.

Fetch Across Commit

When a cursor is open and does fetch row by row, you can not issue "COMMIT" or "ROLLBACK" before all rows in the cursor have been fetched. 

For example,

Above procedures work properly in ORACLE, but it does not work in ALTIBASE HDB and it returns error, "ERR-31168 : Invalid CURSOR".

If COMMIT or ROLLBACK statement is sent, ALTIBASE HDB applies commit or rollback operation to the transaction and closes all open cursors within the transaction. In this case, COMMIT statement is issued after INSERT statement, C1 CURSOR is closed.

Thus client gets error as above.

To solve this limitation, you can

• Execute COMMIT / ROLLBACK statement after all data have been fetched in the cursor.
  For example, you can change example as below.
• Decouple the connection between SELECT statement in CURSOR and another statement.
  In APRE or ODBC/CLI interface, you can make two connections. One is for SELECT statement ( CURSOR ) , the other is for another statement (inside LOOP).

Parallel Query

ALTIBASE HDB does not provide Parallel Query feature. Only one thread per query is allowable.

MERGE statement 

MERGE statement is useful when you want to decide whether insert or update statement is proper according to the existence of the corrsponding rows.

Partitioned table with GLOBAL INDEX

ALTIBASE HDB support Partioned Table feature with local partition index but does not support global index in Partitioned Table.

High Availability

RAC

ALTIBASE HDB doesn't provide RAC(Real Application Cluster).
ALTIBASE HDB provides replication functionality for High Availability Instead of RAC.

TAF (Transparent Application Failover )

ALTIBASE HDB only provides CTF (Connection Time Failover).

CTF refers to the case where the fault is noted at the time of connection to the DBMS, and connection
is made to a DBMS on another available node rather than to the DBMS suffering from the fault,
so that service can continue to be provided.

DBA side

Auditing

ALTIBASE HDB does not support Auditing, that is to say watching DB according to the type of executing SQLs and gathering results of it in ORACLE.

In fact, an audit utility is in use not for same purpose but as a same name in ALTIBASE HDB.

It is utilized for matching rows as a result of investigation of data difference between servers.

Besides it provides a functionality for comparison of data difference between the ALTIBASE HDB server and ORACLE server irregardless of the data modification by replication.

And matching them is available by using that utility.