1) Does ignite use heap space to do the required processing as per the execution plan to retrieve the data from cache which is in off heap memory?
2) Please check the following SQL. This CACHE_1 has around 50 million entries. select * from ( select * from CACHE_1 where filter1 = ? (Q1) UNION select * from CACHE_1 where filter2 = ? (Q2) UNION select * from CACHE_1 where filter3 = ? (Q3) ) order by column1 asc , column2 desc Lets assume the query Q1,Q2 and Q3 returns 1 million records each, so total 3 million records. Let's assume that data query execution is local to the node. Page size is set to 500 to utilize the heap space efficiently or to avoid out of memory errors. In this scenario does ignite brings all 3 million records in heap space and then does the union operation and then sorts it on column1 and column2? I want to keep the memory foot print low. So I am just trying to understand how ignite executes the sql internally. Can someone please explain it? Thanks, Prasad
