Will database be hit 2 times by this code?

Question

I am trying to improve performance of an api. I need to know whether the second line that's marked will hit database too ? as I want to minimise that.

     StringBuffer queryBuf = new StringBuffer("some query in SQL");
--------->StringBuffer queryBuf2 = new StringBuffer(" SELECT DISTINCT PP.ID FROM ( " + queryBuf + ") PP ");
        Query query1 = getSession().createSQLQuery(queryBuf2.toString());
        query1.setReadOnly(true);
        ScrollableResults results = query1.scroll();
        if (results.isLast() == false)
            results.last();
        int total = results.getRowNumber() + 1;
        results.close();
        logger.debug(">>>>>>TOTAL COUNT<<<<<< = {}", total);

That line creates a string buffer, like the two above. None of those "hit the database". — Mat, Jul 30 '13 at 10:03
You can use Integer count= ((Long)query1.uniqueResult()).intValue(); to get the count. — Marginean Vlad, Jul 30 '13 at 10:38

score 2 · Answer 1 · answered Jul 30 '13 at 10:04

2

No. Only the line ScrollableResults results = query1.scroll(); executes sql.

Also, you may want to use SQL COUNT

answered Jul 30 '13 at 10:04

eerorika

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score 2 · Answer 2 · answered Jul 30 '13 at 10:12

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Its plain and simple it wont hit , you are just creating StringBuffer objects.

answered Jul 30 '13 at 10:12

saurav

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score 2 · Answer 3 · answered Jul 30 '13 at 10:43

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you are just create a string buffer. its not hitting the db. If i right this code may give compile error.

answered Jul 30 '13 at 10:43

maXfenda

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score 1 · Accepted Answer · answered Jul 30 '13 at 10:04

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I need to know whether the second line that's marked will hit database too ?

You are constructing StringBuffer objects in first three lines , why should it hit the DB ! You can use StringBuilder if synchronization is not required !

answered Jul 30 '13 at 10:04

AllTooSir

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You are right but i didn't understand then how "total" gets evaluated and showing correct no of rows, when the "results" is dependent on "query1" and "query1" on "queryBuf2". – newProgramer Jul 30 '13 at 10:16

score 1 · Answer 5 · answered Jul 30 '13 at 10:04

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No it will not hit the database. It will query from the buffer created by first query.

answered Jul 30 '13 at 10:04

hima

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Will database be hit 2 times by this code?

5 Answers5