Restrictions

CIS support for HANA includes some restrictions.

CIS for HANA is supported only in SAP ASE servers that are configured for threaded kernel mode. You cannot use CIS for HANA in SAP ASE servers that are configured for process mode.
CIS for HANA does not support update or delete commands that include a where current of cursor_name clause.
CIS for HANA does not support sensitive cursors.
CIS for HANA does not support large object (LOB) parameters.
You cannot issue queries that include text pointers to the remote HANA server because HANA LOBs do not support text pointers.
If you issue create index...desc to create an index on a proxy table, the desc parameter is not generated for the create index statement. Instead, the index in the remote HANA table is created with an asc parameter.
alter table statements to remote tables include restrictions. You cannot:
- Include partition clauses
- Include referential integrity constraints
- Add constraints
- Replace columns
- Change locking schemes
- Add columns with check conditions
- Add columns with unique or primary key constraints
A single alter table command cannot include more than one of these parameters:
- add column_name
- modify column_name
- drop column_name
You must define a unique index on the base table for positioned update and delete statements, and the unique index must have at least one nonnullable column. SAP ASE issues an error message if this unique index is unavailable.
You cannot use distributed transaction management (DTM) with two-phase commit on HANA proxy tables.
You cannot include save tran and rollback to savepoint statements in transactions that involve HANA proxy tables.
rollback tran operations issued on transactions involving HANA proxy tables roll back all statements up to the first statement in the current transaction. All statements after the rollback tran operation execute normally.
You cannot issue rollback trigger on triggers that include HANA proxy tables.
Search clauses can contain only the input parameters (and none of the resultant columns) for queries using proxy tables that are mapped to an external HANA procedure. For example, if you create this table:
```
create existing table rpc_table   
(      
   col1 int,      
   col2 int   
) external procedure at "odbchana..SYSTEM.MYPROC"
```
Then issue the following query; the search results are not narrowed, because the query specifies col1:
```
select * from rpc_table where col1 > 100
```
You cannot use null as a value for input parameters for proxy tables that are mapped to an external HANA procedure. For example, this is not allowed:
```
select * from rpc_table where _p1 = null
```
CIS for HANA does not support bulk operations.
Implicit conversions may cause a loss of precision for millisecond values for SAP ASE bigdatetime and bigtime datatypes that are mapped to a HANA timestamp datatype. SAP ASE stores the millisecond portion of bigdatetime and bigtime values using 6 digits (for example hh:mi:ss.zzzzzz). However, HANA stores the millisecond portion of bigdatetime and bigtime values in 7 digits in its timestamp datatype. Transmitting values using ODBC is precise up to 3 digits. Implicitly converting values from ODBC to the SAP ASE internal format may further depreciate the precision, because the available conversion formats support only up to 3 digits.
You must fully pad binary values when you specify them in a search clause. In the first select statement below, the value of c1 (0x123) is not fully padded, and therefore returns no results. The second select statement uses a fully padded value (0x012300) for c1, and thereby returns a valid result:
```
1> create table cb(c1 binary(3)) at 'odbchana..SYSTEM.cb'
2> go
1> insert into cb values(0x123)
2> go
(1 row affected)

1> select * from cb where c1 = 0x123
2> go
c 1
--------
(0 rows affected)

3> select * from cb where c1 = 0x012300
c1
--------
0x012300
(1 row affected)
```

Restrictions for quoted identifiers when using CIS for HANA include:

Object names in object definitions included with DDL statements must include at least one uppercase letter.
Quoted identifiers for DML statements must include at least one uppercase letter.
CIS for HANA raises an error for DDL statements that include an object definition that contains only lowercase characters. For example, this raises an error: <hanaserver>..<schema>.table1.
SAP ASE creates object names in proxy tables without quotes. Consequently, SAP ASE cannot determine whether to add quotes to a quoted identifier when executing a DML statement if the remote quoted identifier contains only lowercase characters (for example column1). That is, SAP ASE creates the object name in the same way for column1 as for COLUMN1, because SAP ASE defaults to lowercase. As a workaround, use trace flag 11242, which quotes all lowercase identifiers are quoted.
CIS for HANA does not support bracketed identifiers (that is, [ and ]).