Hybrid LOB: INSERT/UPSERT Performance

[dominik_kastner]

Dear HANA Experts,

i am considering converting some VARBINARY Columns to Hybrid LOB and i am curious on the performance impact for WRITE operations. For READ it is clear to me that all LOB Data bigger some threshold (>1KB in default) is stored on Disk. So there is some I/O overhead for this.

But for the WRITE Performance, i am not sure: is there some additionally WRITE I/O for INSERT/UPSERT necessary, besides the usual sync. commit on LOG disk? is for Hybrid LOB delta store in use? 

My concern originates from SAP note 2000002, point 10: "Increased runtime of INSERT operation on table with hybrid LOB field" -> "INSERTs in hybrid LOBs have to perform disk I/O if the configured memory threshold is exceeded and the data is stored in a disk LOB."

I hope some Experts here in the HANA community can help me with this.

Thank you very much

BR Dominik

[HakanHaslaman]

As I know, INSERT/UPSERT operations on Hybrid LOBs can have additional disk I/O overhead if the LOB size exceeds the configured memory threshold (default >1KB). Small LOBs stay in memory (delta store), larger ones go directly to disk. If exceeding the threshold, disk I/O happens during insertion, impacting performance. Hybrid LOBs do not use delta store like regular column data as I know, leading to direct disk writes.

For frequent INSERTs/UPSERTs, performance may degrade if large LOBs frequently exceed the threshold.