Hash Aggregate

Partial Aggregation

Noticias externas — Fri, 18 Jan 2008 23:05:27 GMT

In some of my past posts, I've discussed at how SQL Server implements aggregation including the stream

Partial Aggregation

Craig Freedman's SQL Server Blog — Fri, 18 Jan 2008 22:17:51 GMT

In some of my past posts, I've discussed at how SQL Server implements aggregation including the stream

Aggregation WITH ROLLUP

Noticias externas — Fri, 21 Sep 2007 21:41:35 GMT

In this post, I'm going to discuss how aggregation WITH ROLLUP works. The WITH ROLLUP clause permits

Aggregation WITH ROLLUP

Craig Freedman's WebLog — Fri, 21 Sep 2007 20:47:54 GMT

In this post, I'm going to discuss how aggregation WITH ROLLUP works. The WITH ROLLUP clause permits

PIVOT Query Plans

Craig Freedman's WebLog — Mon, 09 Jul 2007 21:29:00 GMT

In my last post , I gave an overview of the PIVOT operator. In this post, I'm going to take a look at

re: Hash Aggregate

Craig Freedman — Thu, 17 May 2007 20:28:03 GMT

In the discussion of memory and spilling, I originally wrote that “with a hash join, if we run out of memory, we spill some of the rows already in memory to disk to free some space. With a hash aggregate, we keep the existing groups in memory. When we run out of space for new groups, we simply begin spilling any new input rows that do not belong to an existing group.” This description of the algorithm was not correct. I’ve corrected the post as follows: “We spill one or more buckets or partitions including any partially aggregated results along with any additional new rows that hash to the spilled buckets or partitions.”