次の表があるとします。
SITE
----
id name reference
----------------------------
1 AAM 783C3502-19B9-EFA7-D6B8874219EF6734
3 AOC B4E82054-C09F-4338-50C809C7515E755B
SERVICE
-------
id name type
-----------------------------------
1 Outbound data Web Hosting
2 Inbound data Web Hosting
3 API Data API Traffic
4 Site Space Disk Space
5 DB Space Disk Space
USAGE
-------
site service timeperiod detail
-----------------------------------------------
1 4 477 21997
1 5 477 53
1 4 479 1991
1 5 479 53
3 4 477 448
3 5 477 10
3 4 479 448
....
TIMEPERIOD
----------
id year month day when
-----------------------------------------
477 2012 7 2 2012-07-02
479 2012 7 3 2012-07-03
次のクエリは、2つのディスクスペースカテゴリ（DBスペースとサイトスペース）で特定のWebサイトの1か月間のアクティビティを平均します。
各サイトのUUIDで個別にユニオンクエリを実行すると、
UUID：783C3502-19B9-EFA7-D6B8874219EF6734
SELECT `month`,`year`,
AVG(`usage`.detail) as dbsize, 0 as sitesize,
AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage` ON site.reference
IN ('783C3502-19B9-EFA7-D6B8874219EF6734')
AND `usage`.site = site.id
INNER JOIN service ON service.name = 'DB Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
UNION
SELECT `month`,`year`, 0 as dbsize,
AVG(`usage`.detail) as sitesize,
AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage`
ON site.reference IN ('783C3502-19B9-EFA7-D6B8874219EF6734')
AND `usage`.site = site.id
INNER JOIN service
ON service.name = 'Site Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
次の結果が得られます。
month year dbsize sitesize totalsize
-------------------------------------------------
7 2012 53.0000 0.0000 53.0000
7 2012 0.0000 2002.7273 2002.7273
UUID：B4E82054-C09F-4338-50C809C7515E755B
SELECT `month`,`year`,
AVG(`usage`.detail) as dbsize, 0 as sitesize,
AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage`
ON site.reference IN ('B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service
ON service.name = 'DB Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
UNION
SELECT `month`,`year`, 0 as dbsize,
AVG(`usage`.detail) as sitesize,
AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage`
ON site.reference IN ('B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service ON service.name = 'Site Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
次の結果が得られます。
month year dbsize sitesize totalsize
-------------------------------------------------
7 2012 10.0000 0.0000 10.0000
7 2012 0.0000 448.6364 448.6364
これまでのところすべてが順調です。
ただし、次のように複数のサイトUUIDを渡す場合：
SELECT `month`,`year`, AVG(`usage`.detail) as dbsize, 0 as sitesize, AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage` ON site.reference
IN ('783C3502-19B9-EFA7-D6B8874219EF6734','B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service
ON service.name = 'DB Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
UNION
SELECT `month`,`year`, 0 as dbsize, AVG(`usage`.detail) as sitesize, AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage` ON site.reference
IN ('783C3502-19B9-EFA7-D6B8874219EF6734','B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service
ON service.name = 'Site Space'
AND service.id = `usage`.service
INNER JOIN timeperiod
ON timeperiod.when > '2012-07-01'
AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
次の結果が生成されます。
month year dbsize sitesize totalsize
-------------------------------------------------
7 2012 31.5000 0.0000 31.5000
7 2012 0.0000 1225.6818 1225.6818
IDを個別に渡す場合よりも、複数のUUIIDの結果はさらに少なくなります。これは、複数のUUIDを処理するクエリが、個々のUUIDクエリの結果を平均化しているためです。
複数のUUIDクエリで個々のUUIDの結果を合計したいと思います。それが理にかなっていることを願っています。
編集
これは、私が使用していた合計クエリのタイプです。
SELECT `month`,`year`, SUM(dbsize) as dbsize, SUM(sitesize) as sitesize, SUM(totalsize) as totalsize
FROM (
SELECT `month`,`year`, AVG(`usage`.detail) as dbsize, 0 as sitesize, AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage` ON site.reference IN ('783C3502-19B9-EFA7-D6B8874219EF6734','B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service ON service.name = 'DB Space' AND service.id = `usage`.service
INNER JOIN timeperiod ON timeperiod.when > '2012-07-01' AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
UNION
SELECT `month`,`year`, 0 as dbsize, AVG(`usage`.detail) as sitesize, AVG(`usage`.detail) as totalsize
FROM site
INNER JOIN `usage` ON site.reference IN ('783C3502-19B9-EFA7-D6B8874219EF6734','B4E82054-C09F-4338-50C809C7515E755B')
AND `usage`.site = site.id
INNER JOIN service ON service.name = 'Site Space'
AND service.id = `usage`.service
INNER JOIN timeperiod ON timeperiod.when > '2012-07-01' AND timeperiod.when < '2012-07-31'
AND `usage`.timeperiod = timeperiod.id
WHERE `usage`.site = site.id
GROUP BY `month`,`year`
) as x
GROUP BY `month`,`year`