Created
February 16, 2018 16:34
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/***************************************************************************** | |
MIT License, http://www.opensource.org/licenses/mit-license.php | |
Contact: help@sqlworkbooks.com | |
Copyright (c) 2018 SQL Workbooks LLC | |
Permission is hereby granted, free of charge, to any person | |
obtaining a copy of this software and associated documentation | |
files (the "Software"), to deal in the Software without | |
restriction, including without limitation the rights to use, | |
copy, modify, merge, publish, distribute, sublicense, and/or | |
sell copies of the Software, and to permit persons to whom | |
the Software is furnished to do so, subject to the following | |
conditions: | |
The above copyright notice and this permission notice shall be | |
included in all copies or substantial portions of the Software. | |
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES | |
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT | |
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, | |
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR | |
OTHER DEALINGS IN THE SOFTWARE. | |
*****************************************************************************/ | |
SET NOCOUNT ON; | |
GO | |
USE master; | |
GO | |
IF DB_ID('Heaps') IS NOT NULL | |
BEGIN | |
ALTER DATABASE Heaps SET SINGLE_USER WITH ROLLBACK IMMEDIATE; | |
DROP DATABASE Heaps; | |
END | |
GO | |
CREATE DATABASE Heaps; | |
GO | |
use Heaps; | |
GO | |
CREATE TABLE dbo.Test ( | |
Id BIGINT, | |
SecondInt BIGINT, | |
Extra INT | |
); | |
GO | |
--This query adapted from pattern attributed | |
--to Itzik Ben-Gan in https://sqlperformance.com/2013/01/t-sql-queries/generate-a-set-1 | |
--Generates 1 million rows | |
WITH cte1(num) AS | |
( | |
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL | |
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL | |
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1), | |
cte2(num) AS (SELECT 1 FROM cte1 CROSS JOIN cte1 AS b), | |
cte3(num) AS (SELECT 1 FROM cte2 CROSS JOIN cte2 AS b), | |
cte4(num) AS (SELECT 1 FROM cte3 CROSS JOIN cte3 AS b) | |
INSERT dbo.Test (Id, SecondInt, Extra) | |
SELECT TOP (1000000) | |
ROW_NUMBER() OVER (ORDER BY (SELECT num)) as Id, | |
100 * ROW_NUMBER() OVER (ORDER BY (SELECT num)) as SecondInt, | |
555 as Extra | |
FROM cte4; | |
GO | |
/* Review statistic creation settings. | |
If model db hasn't been changed, auto create and autop update stats should be on, | |
async is off by default */ | |
select is_auto_create_stats_on, is_auto_update_stats_on, is_auto_update_stats_async_on | |
from sys.databases | |
where name='Heaps'; | |
GO | |
/* This will have a statistic auto-created with the index */ | |
CREATE INDEX ix_Test_SecondInt on dbo.Test (SecondInt); | |
GO | |
/* Running this query will automatically create a column statistic | |
on Extra */ | |
SELECT COUNT(*) | |
FROM dbo.Test | |
WHERE Extra = 'Extra'; | |
GO | |
/* A very simple query: what stats are on the table? */ | |
SELECT stat.* | |
FROM sys.stats as stat | |
join sys.objects as so on stat.object_id=so.object_id | |
join sys.schemas as sc on so.schema_id = sc.schema_id | |
WHERE so.name='Test' | |
and sc.name='dbo'; | |
GO | |
/* More details: what columns are in the stats, when were they last updated */ | |
SELECT | |
stat.auto_created, | |
stat.name as stats_name, | |
sp.last_updated, | |
STUFF((SELECT ', ' + cols.name | |
FROM sys.stats_columns AS statcols | |
JOIN sys.columns AS cols ON | |
statcols.column_id=cols.column_id | |
AND statcols.object_id=cols.object_id | |
WHERE statcols.stats_id = stat.stats_id and | |
statcols.object_id=stat.object_id | |
ORDER BY statcols.stats_column_id | |
FOR XML PATH(''), TYPE | |
).value('.', 'NVARCHAR(MAX)'), 1, 2, '') as stat_cols, | |
stat.filter_definition, | |
stat.is_temporary, | |
stat.no_recompute, | |
sp.modification_counter, | |
sp.rows, | |
sp.rows_sampled | |
FROM sys.stats as stat | |
CROSS APPLY sys.dm_db_stats_properties (stat.object_id, stat.stats_id) AS sp | |
JOIN sys.objects as so on | |
stat.object_id=so.object_id | |
JOIN sys.schemas as sc on | |
so.schema_id=sc.schema_id | |
WHERE | |
sc.name= 'dbo' | |
and so.name='Test' | |
ORDER BY 1, 2; | |
GO |
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