when the in memory data will be unloaded for NSE paged tables?

[lgh0209]

Hello,

I am not sure about when the in memory data will be unloaded for NSE(native storage extension) paged tables?

Based on what?

[Private_Member_467521 · Accepted solution]

Hi lgh0209,

NSE page loadable data can be read into the buffer cache as needed, the flushed or “ejected” from the cache either when no longer needed or when HANA needs to free up space in the buffer cache for other pages. If the same page is required again then it will be read from disk again.

Only “Column loadable” data resides in the main memory (Hot store).

“Page loadable” means data in NSE (Warm store). Page loadable data does not need to reside completely in-memory, like column loadable data, taking. That is because after the table, partition, or column is configured to use NSE, it is NOT loaded into memory anymore, but it is readable by using the buffer cache instead.

Remember the allocation in the Buffer Cache is transient. As soon as another NSE table is read, those pages loaded into the Buffer Cache may be displaced in a least-recently used fashion. Or they may stay there for longer, if there is enough space in the Buffer Cache to accommodate both tables.

Should that help to address your topic, please kindly accept the answer.

Cheers,

Luis 🙂

[lgh0209 · Accepted solution]

You truly answered my question.

Thanks for your explaination.

[Private_Member_467521 · Accepted solution]

Your question was really good Denis. Please kindly 'accept' the answer 🙂

[533190789]

Hi,

We are experiencing a situation wherein, even though there is space in Buffer Cache, the HANA table is loaded into memory. Example -

Buffer Cache free space - 40 GB

Table Size - 10 GB. We unloaded the table in warm storage. When users executed select statements we see around 4 GB of data in memory. 2 GB in Buffer and the remaining is unloaded. We were expecting to save the 4 GB memory loaded into the memory even though it was marked as PAGE Loadable. This is for HANA 2.0 SPS 05 Rev 55. Any suggestion why this could be the case?

Regards,

Kevin Vira