I'm creating application in C++ and found out that storing information in XML file was very prodigally. Despite the possibility to read it without any specific application, random access via DOM or VTD library and possibility to backup by simple copying XML file, it's very RAM-expensive (even while using VTD it's necessary 17GB of RAM). Now, there are 12000 entries and I'm planning to store up to million ones. Each entry contains 37 fields (now, maybe more in future) with different types: string, double, float and 128-bit float. These fields are distributed into 5 groups (hierarchy which is possible by XML tags). I tried to find something more productive with the same benefits. Unfortunately, googling didn't help me because there are so many DBs and DBMSs that I'm totally confused.
The XML file structure:
<paient> <analysis name=""> <result type="">some_data</result> </analysis> <diagnosis> <preliminary></preliminary> <final></final> <diagnosis> ... <patient>
So could advise me a solution for my problem?