如何使用 JPQL、Spring 数据存储库和 Hibernate 为 TimescaleDB `time_bucket` 函数参数化 Postgresql 间隔

How to parameterise Postgresql Interval for TimescaleDB `time_bucket` function with JPQL, Spring Data Repositories and Hibernate

我在 PostgreSQL 13 上使用带有 TimescaleDB 扩展的 Spring Data JPA(下面是 Hibernate,JPA 2.1),并希望使用 time_bucket 函数。这需要 bucket_width 这是一个 INTERVALtime 这是数据的 TIMESTAMP 列。

我想把它放在 Spring 数据存储库中,并想使用 JPQL @Query 将数据提取到代表返回时间的聚合计数、平均值等的投影中水桶。我不想使用本机查询,因为我想与其他一些表连接,并自动填充它们的实体。

我将time_bucket函数注册到我正在扩展的PostgisPG95Dialect,像这样:

public class CustomPostgresqlDialect extends PostgisPG95Dialect {

    public CustomPostgresqlDialect() {
        super();
        this.registerFunction("time_bucket", new StandardSQLFunction("time_bucket", new OffsetDateTimeType()));
    }
}

如果 bucket_width 是硬编码的,则一切正常。但我希望 bucket_width 成为查询方法的参数。

以下工作正常:

 @Query("select sys as system, "
                  + "function('time_bucket', '10 mins', vt.ts) as startTime, "
                  + "count(vt) as total, avg(vt.speed) as avgSpeed "
                  + "from Data vt "
                  + "JOIN vt.system sys "
                  + "where sys.sysId = :sysId and "
                  + "function('time_bucket', '10 mins', vt.ts)  between :from and :to "
                  + "group by system, startTime "
                  + "order by startTime")
  List<SummaryAggregate> getSummaryData(
          @Param("sysId") String sysId,
          @Param("from") OffsetDateTime from,
          @Param("to") OffsetDateTime to);

但是当我尝试参数化间隔时,我无法让它工作。我尝试将间隔作为字符串传递,因为这就是它在硬编码版本中的编写方式:

 @Query("select sys as system, "
                  + "function('time_bucket', :grouping, vt.ts) as startTime, "
                  + "count(vt) as total, avg(vt.speed) as avgSpeed "
                  + "from Data vt "
                  + "JOIN vt.system sys "
                  + "where sys.sysId = :sysId and "
                  + "function('time_bucket', :grouping, vt.ts)  between :from and :to "
                  + "group by system, startTime "
                  + "order by startTime")
  List<SummaryAggregate> getSummaryData(
          @Param("sysId") String sysId,
          @Param("from") OffsetDateTime from,
          @Param("to") OffsetDateTime to,
          @Param("grouping") String grouping);

其中 grouping 传递的值类似于 10 mins.

但是为此我得到了这个错误:

SQL Error: 0, SQLState: 42883
ERROR: function time_bucket(character varying, timestamp with time zone) does not exist
  Hint: No function matches the given name and argument types. You might need to add explicit type casts.
  Position: 61

然后我尝试将其更改为 Duration,因为 Hibernate translates Duration to PostgreSQL Interval types

 @Query("select sys as system, "
                  + "function('time_bucket', :grouping, vt.ts) as startTime, "
                  + "count(vt) as total, avg(vt.speed) as avgSpeed "
                  + "from Data vt "
                  + "JOIN vt.system sys "
                  + "where sys.sysId = :sysId and "
                  + "function('time_bucket', :grouping, vt.ts)  between :from and :to "
                  + "group by system, startTime "
                  + "order by startTime")
  List<SummaryAggregate> getSummaryData(
          @Param("sysId") String sysId,
          @Param("from") OffsetDateTime from,
          @Param("to") OffsetDateTime to,
          @Param("grouping") Duration grouping);

但我仍然遇到同样的错误,这次它认为 Duration 是 bigint 而不是 Interval

SQL Error: 0, SQLState: 42883
ERROR: function time_bucket(bigint, timestamp with time zone) does not exist
  Hint: No function matches the given name and argument types. You might need to add explicit type casts.
  Position: 61

有没有办法使用 JPQL 参数化 Interval

有一种方法,但是您必须为此目的注册一个自定义函数,因为您不能转换为任意 SQL 类型。

public class CastInterval implements SQLFunction {

    @Override
    public boolean hasArguments() {
        return true;
    }

    @Override
    public boolean hasParenthesesIfNoArguments() {
        return true;
    }

    @Override
    public Type getReturnType(Type firstArgumentType, Mapping mapping) throws QueryException {
        return firstArgumentType;
    }

    @Override
    public String render(Type firstArgumentType, List args, SessionFactoryImplementor factory) throws QueryException {
        return "cast(" + args.get(0) + " as interval)";
    }
}

您必须在方言中注册该函数。

因此,如果按指示扩展方言,则可以通过以下方式完成:

 this.registerFunction("castInterval", new CastInterval());

然后你可以这样使用它:function('time_bucket', castInterval(:grouping), vt.ts)