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Statistics auto-updates are generally a good thing–auto-update of statistics is the default behavior in SQL Server. Having the freshest information about the data “shape” helps to inform the best selection of an execution plan for queries. Except for when it …
Continue readingQuestion We have a 3TB OLTP database running Siemens Opcenter MES software at one of our manufacturing plants in China. This is setup in an Always-On Availability group with one secondary node. As this is a manufacturing plant, we are only provided 11 1/2 …
Continue readingQuestion I just learned that indexes can be disabled on a table. Even the clustered index can be disabled. After that, users can’t access the index or the data if clustered index. When will we disable an index? I just don’t understand the use case.
Continue readingQuestion I have a table that consumes almost 1.2 TB of space and has lots of historical data which are mostly irrelevant. Since performing bulk DELETE is going to cause a lot of heavy-lifting, I'm trying to use the concept of horizontal partitioning to create …
Continue readingOver the last weeks & months, I’ve had an increasing number of conversations with folks on the topics of diversity, inclusion, equality, and justice. These discussions we have with coworkers, members of the data community, family and friends are all valuable, …
Continue readingWe’ve all been there. You’ve got a query where the JOIN or WHERE predicate is not SARGable. You’ve read about how this can be a problem, and how bad it is for performance. Alas, you cannot change the query. Sometimes this reason is political, sometimes it’s …
Continue readingThere is a corner case where it makes sense to have a non-clustered index "duplicating" the clustered index. If you have a query that frequently *scans* the table, and ONLY makes use of the clustering key column, the query optimizer will prefer to use the …
Continue readingQuestion At what size should we consider applying Columnstore Index on a table? Is there a SQL Server storage or design guidance? Our Data Warehouse is 5TB total. Additionally, we have tables which are 100GB to 1TB which compose the database. Just curious if …
Continue readingQuestion I have a SQL database that is hosted on Azure. The problem is that the size is getting out of control, I can see up to 99% fragmentation in the Primary Key clustered indexes. I'm able to rebuild all other indexes with online=on option and it won't …
Continue readingQuestion In SQL Server, a non-unique nonclustered index on a rowstore table incorporates the base object’s bookmark (RID or clustering key) at all levels of the nonclustered index structure. The bookmark is stored as part of the nonclustered index key at all …
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