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POAdditional queries in JPA
 

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  1. POAdditional queries in JPA
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    <p>I have two classes <code>InvitedPerson</code> and <code>Flight</code> with a one to one relationship with each other. Here is how they are annotated.</p> <pre><code>public class InvitedTech{ ... @OneToOne(mappedBy="invitedTech", cascade = CascadeType.ALL, fetch=FetchType.LAZY) public Flight flight; @OneToOne(mappedBy="invitedTech", cascade = CascadeType.ALL, fetch=FetchType.LAZY) public Hotel hotel; ... } public class Flight{ ... @OneToOne @JoinColumn(name="invitedTechId", nullable=false) public InvitedTech invitedTech; ... } </code></pre> <p>As you can see <code>Flight</code> is the owner of the relationship and <code>InvitedTech</code> is the other side of this bidirectional relationship. InvitedTech also has a <code>OneToOne</code> relationship with <code>Hotel</code> Now, when I write a simple query to fetch all flights, it triggers three queries in total. 1st which gets me the results, but fires 2 additional queries.</p> <pre><code>List&lt;Flight&gt; flg = JPA.em().createQuery("SELECT flg from Flight flg").getResultList(); </code></pre> <ol> <li>Query that gets all flights (This is the only one that I need)</li> <li>Query with a join between InvitedTech and Flight</li> <li>Query with a join between invitedTech and Hotel</li> </ol> <p>Why are query 2&amp;3 being executed even though I have set FetchType=Lazy. I am not accessing Hotel Information. And Flight should not be queries again as the first query returns the data. </p> <p>After some playing around when I remove <code>mappedBy</code> attribute from both the annotations, those 2 addition queries don't get executed(i.e only 1st gets executed). </p> <p>Why does the <code>mappedBy</code> attribute cause additional queries to be executed even though <code>FetchType=Lazy</code>. Is there a way to stop this?</p>
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    1. USSpartanElite
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    1. CODoes accessing the fields still work without those `mappedBy` attributes?
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    2. COIf you mean accessing InvitedTech fields (Hotel and Flight), they will be null w/o the mappedBy, as JPA does not know of this inverse relationship.
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