Examples of org.apache.openjpa.kernel.PreparedQueryCache

org.apache.openjpa.kernel.PreparedQueryCache

A cache to create and maintain {@link PreparedQuery prepared queries}. To cache a PreparedQuery is two-stage process. In the first stage, {@link #register(String,Query,FetchConfiguration)} register} an identification key and a compiled Query Q to create a hollow PreparedQuery instance P in the cache. In the second stage, after Q executes, {@link #initialize(String,Object)} initialize} the hollow Prepared Query P from the result of execution such as the target database query PQ and its parameters. After initialization, P can be used with re-parameterization for subsequent execution of the original Query Q. The target database query PQ associated to a cached prepared query P may depend upon query execution context such as fetch plan or lock group. This cache, by design, does not monitor the context or automatically invalidate an entry P when the original query Q is executed with context parameters that affect the target query PQ. The user must notify this receiver to invalidate a cached entry P when execution context changes in a way that will modify the resultant database language query PQ. One of the built-in mechanism (available in JPA facade) is to set query hints to either invalidate the query entirely or ignore the cached version for the current execution. @see QueryHints#HINT_IGNORE_PREPARED_QUERY @see QueryHints#HINT_INVALIDATE_PREPARED_QUERY This cache allows customization of whether a query can be cached or not via either explicit marking of certain keys as non-cachable (which is irreversible or strong) or addition/removal of exclusion patterns (which is reversible or weak). @see #markUncachable(String) @see #addExclusionPattern(String) @see #setExcludes(String) @see #removeExclusionPattern(String) @author Pinaki Poddar @since 2.0.0

     * @param result an opaque object representing execution result of a query
     * 
     * @return true if the prepared query can be initialized.
     */
    private boolean postExecute(Object result) {
        PreparedQueryCache cache = _em.getPreparedQueryCache();
        if (cache == null) {
            return false;
        }
        return cache.initialize(_id, result) != null;
    }

    
    /**
     * Remove this query from PreparedQueryCache. 
     */
    boolean invalidatePreparedQuery() {
        PreparedQueryCache cache = _em.getPreparedQueryCache();
        if (cache == null)
            return false;
        ignorePreparedQuery();
        return cache.invalidate(_id);
    }

     * Gets the prepared query cached by the given key. 
     * 
     * @return the cached PreparedQuery or null if none exists.
     */
    PreparedQuery getPreparedQuery(String id) {
        PreparedQueryCache cache = getPreparedQueryCache();
        return (cache == null) ? null : cache.get(id);
    }

Examples of org.apache.openjpa.kernel.PreparedQueryCache

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