This confused me for a few minutes today and I wanted to share to help avoid further confusion. The specific code was this: Names have been changed to protect the innocent. In the above delete statement which table will have rows deleted from it? A: Table1 B: Table2 C: Both Table1 and Table2 D: Neither Table1 and Table2
The question came up as a blog comment of “To delete 100,000 row chunks from a 9,542,067 row table, how about” Thats a great question. I have had to do something very similar lately. The problem that you run into when you are deleting 100,000 rows is lock escalation. When you run a delete statement with just a few rows …
Q & A – Deleting lots of rows from a huge table. Read more »
If you know me, you will know that I really enjoy working on and fixing database corruption, as well as working on SQL Server internals, specifically relating to corruption and page formats. This week a question came up on the #sqlhelp hashtag on Twitter around corruption in a BLOB page. Elizabeth Hunt was nice enough to send it my way, …
#SQLHELP and a mention on Knee Deep in Tech podcast Read more »
The question came up as how to find a link from blog storage that is corrupt back to the table and row that contains that data. The is no link from the blob storage back to the table and row, but this is a link from the data page containing the table and row off to the blob data. …
The REPAIR_ALLOW_DATA_LOSS option for DBCC CHECKDB and DBCC CHECKTABLE can be one of the most misleading and possibly catastrophic options. What the REPAIR_ALLOW_DATA_LOSS option does for DBCC CHECKDB and DBCC CHECKTABLE is to simply just throw away any pages (8k blocks of data) that contain rows. This may mean it is throwing away a couple of rows, or dozens to …
With SQL Server 2017, there was a new compatibility level introduced, level 140 the new SQL Server 2017 Compatibility Level. SQL Server can run in a number of different compatibility levels, but how do you change it and how do you set it. These compatibility levels reflect the version of SQL server. 60 = SQL Server 6.0 65 = SQL Server …
Today I had the opportunity to present on Database Corruption at the PASS Summit 2017 conference. You can download the presentation as a PDF here: Summit 2017 Corruption.pdf Here is the agenda from the corruption presentation. What is Database Corruption Causes of Corruption Detecting Corruption Tracking Corruption Removing Corruption Customer Examples Demo Related Links: Database Corruption Challenge Week 6 of …
Database Corruption Presentation at Pass Summit 2017 Read more »
Today at PASS Summit Microsoft announced a new SQL “Tool” for running queries against SQL Server, called the Microsoft SQL Operations Studio. So what is the Microsoft SQL Operations Studio This appears to be a new cross platform (Mac, Linux, and Windows) for running queries against SQL Server. Perhaps this is a replacement for SQL Server Management Studio, or may …
With over 2000 downloads since the last updated to Database Health Monitor, I figured it was time to get another release of the product out. New Features in 2.6 Added a Job Schedule instance level report. Added an option on the statistics report to show statistics for all databases, and to generate the script to rebuild statistics for all databases. …
Database Health Monitor October 2017 Version Released Today Read more »
It is handy to have a SQL Restore script ready to go for every backup that you run. Here is a script that will help with that.