column store error: search table error: [6915] UNKNOWN_ATTRIBUTE (AttributeEngine)

[Former Member]

Hi All,

I am getting an error while running a select query like:

select count (*) from ( an complex select query with multiple joins)

Error:  SAP DBTech JDBC: [2048]: column store error: search table error:  [6915] UNKNOWN_ATTRIBUTE (AttributeEngine)

SPS09 : Query is running perfectly fine.

SPS10(Rev 101) : Only Inner query is running fine .  The error appears while running the entire query at once.

What is this issue and how can we resolve it? Is it something related to out of memory related scenario? Or Some bug with SPS10 Rev 101 ?

Need a help

Regards,

Rahul Anand

[former_member191717]

Hi

That new error seems to be a known issue that is fixed in Revision 100 and higher.

The workaround to resolve it is to perform an unload of the table, e.g.

"UNLOAD TABLE <schema_name>. <table_name>" and Restart the database

For instructions on Load/Unload a Column Table into/from Memory:

http://help.sap.com/saphelp_hanaplatform/helpdata/en/c1/33165bbb57101493c5fb19b5b8607f/content.htm

To prevent it from happening normally you can perform an unload of the table, see above. Unloading and re-loading will prevent that the issue occurs at all.

For a permanent solution you can upgrade to SAP HANA Revision 100 and higher

Please note that: Before adding columns to a table in productive systems, which may happen in the context of

ABAP transports, plan accordingly in order to avoid unforeseen downtimes. Ideally unload relevant tables first

before applying transports to avoid subsequent activation errors.

Cheers

Kingsley

[Former Member]

Hi Candy/Lars,

I am hoping Rev 102 will resolve our issue.   But before that, need few input regarding Rev 102. As of my knowledge, Rev 102 has been released for HEC Quality Systems.

I just want to know whether it has been released or not other than HEC ?

Thanks & Regards,

Rahul Anand

[Former Member]

Hello,

have you verified this bug in rev102? we've just upgraded to rev102 and it looks like the problem persist (has not been fixed in rev102). Can you someone confirm that?

Martin

Vendavo CZ

[Former Member]

Hi Candy,

Thanks for the suggestion.   But I just want to understand that ...

Is this some kind of bug in Rev 101 ? or Hana configuration related to memory is not set as per standards?

Regards,

Rahul Anand

[candy_zhan]

Hi Rahul,

Your error information is not in detail, so this is just my guess.

There is a HANA bug, MultiColumnJoin fails with UNKNOWN_ATTRIBUTE if parallel CREATE/DROP concat index.

concat attr was deleted from memory during DDL call,  so old readers (transactionally still seeing the concat) failed to read attribute data.

As I know this bug will be fixed in rev102, so I suggest rev102 if it is possible for u.

Best regards,

Candy

[candy_zhan]

Hi Rahul,

I recommend you upgrade to rev102 directly.

Best regards,

Candy Zhan

[lbreddemann]

Wow, that's an impressive recommendation considering that we had no chance to understand the nature of this error so far.

Can you share the rationale for this advise?

[Former Member]

Hi Lars,

What are possible scenario where we get errors like this?

Error:  SAP DBTech JDBC: [2048]: column store error: search table error:  [6915] UNKNOWN_ATTRIBUTE (AttributeEngine)

Regards,

Rahul Anand

[lbreddemann]

Ha!

I don't know that.

The 2048 is the general error that is returned when things go wrong in the column store.

Looking at the UNKNOWN_ATTRIBUTE error, I would guess that there is maybe something wrong with the table data structure. Maybe there is a concat-attribute missing that should've been there.

But the point is: the information available don't allow for any actual analysis.

And simply listing all possible reasons for the error message is not getting us anywhere.

To move forward, please either provide a reproducible example for this or (and I'd recommend this) open a support incident, so that the colleagues can have a more detailed look at what is causing this error.

[Former Member]

Hi Lars,

Thanks for the suggestion

I understand now that the example is not sufficient to draw an analysis, so will try to post it with the reproducible example.

But in the mean time, I have a query...

The table structure ,data and the query is working perfectly fine in SPS09

but the same table with same data is throwing us error in SPS10 . ??

Regards,
Rahul Anand

[lbreddemann]

We don't know what causes the error (yet) - so what is your question?

[candy_zhan]

Hi Lars,

Do you feel bug 68378 might relate?

Best regards,

Candy

[lbreddemann]

I don't have access to the the bug tracking tool (as I am not a member of HANA core development or support) so I really cannot tell, whether this bug or another might be related.

From your other reply I take it that the keyword search for UNKNOWN_ATTRIBUTE lead to this bug number.

So, yes, why not? Matching error messages is an indicator for related behaviour.

My point is that we still don't know whether or not this is actually the error present here. If the description for the bug is correct, then the next execution of the statement should start off with the state that the concat attribute is not there and shouldn't get the error.

I assume this is not the case here, because most people just go and try again rather than immediately open a support incident or SCN thread (and rightly so).

Given all that we don't know I'd say indicating a revision upgrade as the first step of troubleshooting is a bit far out, don't you think? It's a major activity in a landscape to install  new revision and beside that it takes time to do it, there might be a workaround for the problem that could be used for now instead.

Depending on the situation, maybe reactivating the underlying information model (if there are  modelled views used here) could already fix the situation.