Resolution: Won't Fix
Affects Version/s: None
Fix Version/s: None
Component/s: contrib - DataImportHandler
I just reduced the time for my full-import (solr 6.0.1) on an oracle-database for 1.4mio documents from 36 hours to 5 hours by setting the oracle session-parameter "CURSOR_SHARING=FORCE".
Here I found one with the same problem:
I have 1.4 mio documents and for every document i need 12 queries to collect sub-information for the actual document.
This makes about 17mio sql-Statements to oracle for a full-import.
As DIH doesn't use bind-variables (https://docs.oracle.com/cd/B28359_01/appdev.111/b28765/addfunc.htm#TDPJD210), every select looks "different" for oracle and a full parse (analyze statement, get optimal query-plan,..) has to be done 17mio times.
By setting the session parameter "CURSOR_SHARING=FORCE", which can be done in an on_logon_trigger, oracle replaces all literals ins SQL with bind-variables and then can skip the hard-parse.
This reduced my full-import-time from 36 hours to 5 hours. (With this you get only 13 different sql-statements compared to 17mio different statements before.
As oracle states, that setting the CURSOR_SHARING=FORCE is only a workaround, it would be fine when DIH would use bind-variables for the variables.