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Broadcasting with Multiple Application Servers

sap_cohort
Active Contributor
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Hi, If I schedule a query broadcast to fill olap cache and I have multiple production servers which App server(s) will get the cache filled? What ever server the broadcast job runs on?

If anyone can give some insight it is greatly appreciated.

Thanks,

Ken Murray

Accepted Solutions (1)

Accepted Solutions (1)

Former Member
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Kenneth,

This depends on how your system is setup. By default it will store the results in main memory of the app server the broadcast is run on. If you have your system setup to write the cache to a flat file, cluster, or blob table to share across app servers, then it will write to the appropriate area.

Thanks,

Jeff

sap_cohort
Active Contributor
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When I Broadcast a Query to prime cache I need it to be available on all of the servers and I wouldn't want to use the cache via flat file as that would probably be a lot slower than Main Memory. Any way to broadcast a query cache so that all of the servers are updated?

Thanks,

Ken Murray

sap_cohort
Active Contributor
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OK, Let me see if I have this right.

1. If the OLAP cache is set to main memory than the OLAP Cache only gets created on the server in which it is run? So if I have 4 servers with load balancing then it is possible for the next 3 people who run the query to not benefit from the initial OLAP Cache created.

2. If I change it to BLOB than any of the query runs on any server would access the initial OLAP Cache Entry that was created?

3. Where is this BLOB Cached created and made available from? The DB Server or on 1 of the APP Servers?

4. If SAP can make BLOB Cache available to all servers then why couldn't they make Main Memory Cache available to all servers?

Thanks for any comments and help!

Ken Murray

Former Member
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1. If the OLAP cache is set to main memory than the OLAP Cache only gets created on the server in which it is run? So if I have 4 servers with load balancing then it is possible for the next 3 people who run the query to not benefit from the initial OLAP Cache created.

<i>--> Next 3 people will benefit only if they log in to the same server, if cache was created in app server 1 and next 3 login to app server 2, 3 and 4 they wont hit the cache from app server 1.</i>

2. If I change it to BLOB than any of the query runs on any server would access the initial OLAP Cache Entry that was created?

<i>--> Yes.</i>

3. Where is this BLOB Cached created and made available from? The DB Server or on 1 of the APP Servers?

<i>--> DB Server</i>

http://help.sap.com/saphelp_nw04/helpdata/en/00/241da12ef84f40bb6ecd3ae73d8b58/content.htm

4. If SAP can make BLOB Cache available to all servers then why couldn't they make Main Memory Cache available to all servers?

<i>Main memory is specfic to a server like how you have RAM for your PC, this is not accessible by other system. BLOB is Database and can be accessed by multiple systems.</i>

Thanks.

sap_cohort
Active Contributor
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Thanks so much for your time! You've been very helpful!

Ken Murray

Former Member
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Just a clarification - when you choose one of the persistent cache options, flat file, cluster, or BLOB, there are two options - cache on the local appl server, or what SAP calls Cross Application (the terminology on teh screens ha schanged a little with SPs - might also be referred to as Cross System / Cross Server. The Cross Application is the one you want, when you are looking load teh data to a single cache and have any user form any of the appl servers access it.

Generally, what have seen, is tha tCluster is recommended for smaller cached result sets and BLOB for larger results (>1MB).

Answers (0)