Re: MySQL ResultSet - count rows?

Lew wrote:
Arne Vajhøj wrote:
Dyreatnews@xxxxxxx wrote:
On the other hand; if you're using a scrollable result set, you can loop
over it to find the size,

You don't even need to loop.

Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE);
ResultSet rs = stmt.executeQuery("SELECT * FROM T1");
rs.last();
int n = rs.getRow();
rs.first();

But I would never use that construct.

Arne: What are the dangers of that construct?

I'm guessing that it's the overhead of going first / last / first on large datasets.

Most (maybe all) drivers will implement that scrollable
feature by reading all data into memory.

medium data size => bad performance

large and huge data => OutOfMemoryError

Arne
.

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