为了解决上述问题,一般采用对查询列进行排序,将每行数据映射为顺序id, 类似于row_number()或dense_rank()或rank()的窗口函数。 然而这种情况下对查询列进行依次排序,可见性能上肯定影响很大。 那么Delta是如何实现的?又是如何解决上述问题的? Delta采取了降低精度的办法,将连续的值视为一个单位,将任意的查询列转...
Snowflake Quiz –Place the Rows on the Micro-Partition The First Row is on the Proper Micro-Partition Place the Remaining Rows on the Proper Micro-Partitions The Rows are on the Proper Micro-Partitions Snowflake will use Columnar Storage Quiz – Can you Place the Metadata Correctly? Answer –...
SQL Server and Snowflake both support the COALESCE function. This function returns the value of its first non-NULL argument. If all arguments have NULL values, it returns NULL. Unlike ISNULL or IFNULL(NVL), COALESCE can accept more than two arguments. Below is an example of COALESCE functio...