jooq扩展了现有的方言。采用MySQL方言到apache Hive方言

不幸的是,扩展jOOQ以完全支持一种新的SQL方言并不是很简单。随着时间的推移,jOOQ的API已经扩展,支持一组标准和特定于供应商的SQL语法变体。虽然Apache Hive方言可能看起来与MySQL相似,但jOOQ的内部可能需要实现许多细微的差异。LIMIT的不同实施方式。。OFFSET条款只是一个问题。也就是说,将jOOQ与“未知”或“不受支持”的方言一起使用通常不是一个好主意。

解决方案:短期内

从短期来看,您可能需要修补jOOQ渲染的SQL。实现这一点的最佳技术是使用ExecuteListener,如本文所述:

• http://www.jooq.org/doc/latest/manual/sql-execution/execute-listeners/
• http://www.jooq.org/javadoc/latest/org/jooq/ExecuteListener.html

收到“renderEnd()”事件后,您将能够访问渲染的SQL,并使用正则表达式或您喜欢的任何技术对其进行修改。

解决方案:从长远来看

从长远来看,如果/当 #2337 已实现(但我们可能不会实现)

这是最肮脏的解决方案:)JOOQ用户组不幸没有回答:(

public class CountRatingQueryBuilder {

    private static final String SCORING_TABLE_NAME = "web_resource_rating";

    private final Connection connection;
    private final ScoringMetadata scoringMetadata;

    private final SelectSelectStep select;
    private final Factory create;

    public CountRatingQueryBuilder(Connection connection, ScoringMetadata scoringMetadata){
        this.connection = connection;
        this.scoringMetadata = scoringMetadata;

        create = new Factory(this.connection, SQLDialect.MYSQL);
        select = create.select();

        withSelectFieldsClause();
    }

    public CountRatingQueryBuilder withLimit(int limit){
        select.limit(limit);
        return this;
    }

    public CountRatingQueryBuilder withRegionId(Integer regionId){
        select.where(REGION_ID.field().equal(regionId));
        return this;
    }

    public CountRatingQueryBuilder withResourceTypeId(int resourceTypeId){
        select.where(RESOURCE_TYPE_ID.field().equal(resourceTypeId));
        return this;
    }

    public CountRatingQueryBuilder withRequestTimeBetween(long beginTimestamp, long endTimestamp){
        select.where(REQUEST_TIME.field().between(beginTimestamp, endTimestamp));
        return this;
    }

    public CountRatingQueryBuilder withResourceId(int resourceId){
        select.where(RESOURCE_ID.field().equal(resourceId));
        return this;
    }



    protected void withGroupByClause(){
        select.groupBy(REGION_ID.field());
        select.groupBy(RESOURCE_TYPE_ID.field());
        select.groupBy(RESOURCE_ID.field());
        select.groupBy(CONTENT_ID.field());
    }

    protected void withSelectFieldsClause(){
        select.select(REGION_ID.field());
        select.select(RESOURCE_TYPE_ID.field());
        select.select(CONTENT_ID.field());
        select.select(RESOURCE_ID.field());
        select.select(Factory.count(HIT_COUNT.field()).as(SUM_HIT_COUNT.fieldName()));
    }

    protected void withFromClause(){
        select.from(SCORING_TABLE_NAME);
    }

    protected void withOrderByClause(){
        select.orderBy(SUM_HIT_COUNT.field().desc());
    }

    public String build(){
        withGroupByClause();
        withOrderByClause();
        withFromClause();
        return select.getSQL().replace("offset ?","");//dirty hack for MySQL dialect. TODO: we can try to implement our own SQL dialect for Hive :)

    }

    public List<ResultRow> buildAndFetch(){
        String sqlWithPlaceholders = build();

        List<ResultRow> scoringResults = new ArrayList<ResultRow>(100);
        List<Record> recordResults = create.fetch(sqlWithPlaceholders, ArrayUtils.subarray(select.getBindValues().toArray(new Object[select.getBindValues().size()]),0, select.getBindValues().size()-1));//select.fetch();
        for(Record record : recordResults){
            ResultRowBuilder resultRowBuilder = ResultRowBuilder.create();

            resultRowBuilder.withContentType(scoringMetadata.getResourceType(record.getValue(RESOURCE_TYPE_ID.fieldName(), Integer.class)));
            resultRowBuilder.withHitCount(record.getValue(SUM_HIT_COUNT.fieldName(), Long.class));
            resultRowBuilder.withUrl(record.getValue(CONTENT_ID.fieldName(), String.class));
            scoringResults.add(resultRowBuilder.build());
        }
        return scoringResults;
    }

}