Hi,
i am wondering how does the OData communicate HANA, when users consume data via OData Services. I read from UI5 document that "OData Model is a server side model", that means all data are held on server (XS Engine). I also found the following two statements, which retrieve data from HANA according my OData definition, were created in the HANA SQL Plan Cache, when i called the OData Service via URL at the very first time.
New statements in SQL Plan Cache:
OData Service definition: ("TEST"."BBBB" is a simple table)
service {
"TEST"."BBBB" key generate local "GenID";
}
After that, i called this OData Service again and again, even updated the record in BBBB. The above two statements including all their infos stayed no change. There was also no more related entry created in Plan Cache.
Actually, if the OData called after updating, new query has to be executed on HANA again. The LAST_EXECUTION_TIME are ? in Plan Cache, does that mean, the execution time of such query from OData is not displayed / recorded? Or there are even other related queries but not shown in the Plan Cache?
The second concern is the performance of the OData. Does XS Engine really persistent (in application level) all data for OData Services? If that is true, one must be very careful when defining the OData Service on big data to avoid system crash. However, since we don't see all information of queries from OData Service in Plan Cache, could it be true that HANA executes some hidden queries created dynamically according the user request on OData Service?
Regards,
Hai