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what's the difference between SYSTEM db using multi and non-multi container connections

glen_spalding
Participant
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I re-did my work, see new version below.

This is an edit of my original question

This time i have screen shot my connections in studio. Same order as above.

  1. Use the plain old way non-tenant "HXE(SYSTEM)" (left)
  2. Use the multi-tenant method (not using SYSTEMDB option), specifically naming the SYSTEMDB tenant , "SYSTEMDB@HXE (SYSTEM)" (middle)
  3. Use the multitenant method (using SYSTEMDB option), "SYSTEMDB@HXE (SYSTEM)" (right)

I can see the two ways of accessing the SYSTEMDB via the multi-tenant yields the same results, however, as you can see with the old way, it still gives different results. The older way does not have the 5 "SYS_..." Schemas. How comes as we are still using SYSTEM user and there is only one system therefore one SYSTEMDB (as this is a HANA 2.0 install). I was expecting the older connection to still be able to see everything including the 5 "SYS_..." Schemas.

Am I making myself clear? Do you see what I mean ?

dvankempen
Product and Topic Expert
Product and Topic Expert
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Answer updated

dvankempen
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Product and Topic Expert
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Accepted Solutions (1)

Accepted Solutions (1)

dvankempen
Product and Topic Expert
Product and Topic Expert
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Hi Glen,

UPDATED

Configuration A connects to a different database.

Configurations B and C connect to the system database (although personally I would consider configuration B as a bug, as SYSTEMDB is not a tenant).

In the initial single database container configuration, the indexserver service hosts the database while the nameserver owns the topology (particularly relevant for a multiple host system). The indexserver is the only service configured with a SQL port: 3<instance_number>15.

In a multi-tenant database container (MDC) configuration, each tenant database is hosted by an indexserver service, while the nameserver host SYSTEMDB. Both the nameserver and indexserverS (plural) listen to SQL ports.

To ease the migration to tenant databases, an MDC system is created with a "default" tenant which listens to the original SQL port of a single-container system 3<instance_number>15. The nameserver service (SYSTEMDB) listens to 3<instance_number>13, while all subsequent tenant listen to 3<instance_number>40 and beyond.

To connect to the system database using configuration A, you would need to specify the SQL port of the nameserver. Using the instance number will always point to the indexserver of the default tenant, when available. The description field plays no role for the configuration.

=====================================================================================

When connected to the system database, this query returns the list of databases. When connected to a tenant, the same query only returns the current database.

select * from m_databases;

The SAP HANA Database entry applies to SAP HANA 1.0 release systems in single-container mode. The SQL port connects to indexserver service, which hosts the only database on the system. There is no system database and there are no tenant database(s). When you use this entry for a multitenant database, assuming default parameters, you will be connected to the default tenant database. When you want to make a connection to the system database, you would have to change (and know) the SQL port. For instance number 00: 30013 = system database; 30015 = (default) tenant; 30040 = 1st tenant, 30043 = 2nd tenant, etc.).

To make this easier, the SAP HANA Database (Multitenant) entry was added. Here you can simply select which database to connect to (without knowing the SQL port).

For more information about the difference between SAP HANA 1.0 and 2.0 regarding tenant databases and other aspects, see

glen_spalding
Participant
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Hi Denys, yes i had it a liitle wrong

I re-did my work, see new version below. This time i have screen shot my connections in studio. Same order as above.

  1. Use the plain old way non-tenant "HXE(SYSTEM)" (left)
  2. Use the multi-tenant method (not using SYSTEMDB option), specifically naming the SYSTEMDB tenant , "SYSTEMDB@HXE (SYSTEM)" (middle)
  3. Use the multitenant method (using SYSTEMDB option), "SYSTEMDB@HXE (SYSTEM)" (right)

I can see the two ways of accessing the SYSTEMDB via the multi-tenant yields the same results, however, as you can see with the old way, it still gives different results. The older way does not have the 5 "SYS_..." Schemas. How comes as we are still using SYSTEM user and there is only one system therefore one SYSTEMDB (as this is a HANA 2.0 install). I was expecting the older connection to still be able to see everything including the 5 "SYS_..." Schemas.

Am I making myself clear? Do you see what I mean ?

thanks

glen_spalding
Participant

Hi Denys

What is the difference between the default tenant, and the 1st tenant? i am not clear on this.

ta

dvankempen
Product and Topic Expert
Product and Topic Expert

Updated the answer to include a comment on this question

glen_spalding
Participant

Hi Denys,

i took a little time and a few reads, and i can now understand from your explanation above.

i confused myself a little, when i entered the "description" of configuratio A as "SYSTEMDB". like you say, that means nothing to the config.

so all in all, i am very happy, cheers for your time, effort and knowledge

dvankempen
Product and Topic Expert
Product and Topic Expert
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You are most welcome, Glen. Thanks for your question!

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