Why are result sets so large? [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 12 years ago.

Why are result sets from data bases so large? I typically get result sets that are around a million rows, each of which contains a couple of numerics, a varchar(75), a big int...whatever. Probably not much more than 100 bytes per row. And yet it takes up开发者_StackOverflow社区 6 GB! Is this typical behavior? My stack is Postgres + JDBC + Spring - I don't have any experience with other technologies.

---

The java.sql.ResultSet itself will typically only have a couple dozen rows of data buffered at any time (configurable).

Now if you load all those rows into memory as Java objects, then you'll see large amounts of memory used. A String, for instance, has two bytes per char, two objects headers, an offset, two lengths and a cached hash value. BigInteger is similar. It all adds up. Use a profiler.

You might have better luck with a cached row set. That or don't load the entire set of results at once.

---

We're gonna need to see a Query to see why it's so big. Maybe you're not joining tables right. (I wish I could comment that...)