Schema Mapping

[Former Member]

Hi Gurus, I have a simple question.

I have two schemas (SchemaA and SchemaB) on the one system

I have a query "select * from SchemaA.Table1"

I have schema mapping to map SchemaA (Authoring) to SchemaB (Physical)

SchemaA has a Table1. SchemaB does not have a Table1.

The query will attempt to read from SchemaB and will not find Table1 there. At that point will I get an error or will it then revert to SchemaA.Table1 and return data?

Thanks

Cliff

[vivekbhoj]

Hi Clifford,

If you already have two physical schemas in the System and you try to do Schema Mapping, you will get an error.

Lets say you have table T1 in Development System in Schema SD1 and now you transported the content based on Table T1 to Quality System but in Quality System you don't have Schema SD1 but you have table T1 inside Schema SQ1.

Then in such case you will use Schema Mapping where SD1 will be your Authoring(Logical) Schema and SQ1 will be your Physical Schema

Regards,

Vivek

[Former Member]

Thank you for that. You are saying if I have two physical schemas on one system I can't treat one as the authoring and map to the other. The reason I ask is that the CEI config guide instructs me to do just that.

I just did a search on the string "is already existing as physical schema" and found it in a tutorial where the author trues to map one authoring schema to two physical schemas. (Yes I know the message is the reverse of the error). It makes sense you can't point one authoring schema in two directions.

My situation is different. I'm merely mapping from one schema to another where both physically exist on the server.

Cheers

Cliff

[vivekbhoj]

Hi Clifford,

I guess you read below document

http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/303423d1-b8b8-3010-3cad-b0a697acb...

Here also they are using Logical Schemas(SAP_ECC and Z_ECC) and mapping them to two different physical schemas.

As far as I know Physical Schema Mapping is not possible in HANA, did you try mapping schemas  in your system?

Regards,

Vivek

[Former Member]

Hi Vivek

You are correct, that is the document I found. In section 4.2 they attempt to map one authoring schema (SAP_ECC) to two physical schema. The message occurs as soon as they make the second addition of the authoring schema before they even get to enter the name of the second physical schema. This makes sense because what mapping says if "in your query replace the reference to the authoring schema with a reference to the physical schema". It can't replace it with two different physical schemas.

At this point I have not tried the mapping. We're having another issue with the replication. Currently only 20 of our 190 tables come across. The others sit in a "scheduled" status even though they're all real time. As soon as that's sorted I will test it and post my results.

Just so you have some background my situation is this. We have an instance of CEI running on Hana schema SAPNWABAHDB. We want to bring in CRM data. The config guide instructs us to use SLT to bring the data from the CRM system and then to use schema mapping. SLT forces us to create a new schema. We named it CRMTOCEI. Now we need to use schema mapping to point from authoring (SAPNWABAHDB) to physical (CRMTOCEI). My understanding is CEI should then ignore the presence of SAPNWABAHDB and run entirely from CRMTOCEI. You have raised the possibility that such mapping is not possible.

Even if the mapping is possible by next concern is this: SAPNWABAHDB has 28000 tables but the guide instructs us to replicate only 190. I assume some of the other tables must be used by CEI. (It's hard to believe SAP would build a system with 28000 unused tables). Once the mapping is in place CEI will not find most of the tables on the CRMTOCEI schema.

Cheers

Cliff