Widening Identity Columns

Aaron Bertrand looks at converting an identity integer into an identity bigint:

This is a very disruptive change to the structure of the table, obviously. (And an interesting side observation: the physical order of the columns, RowID and filler, have been flipped on the page.) Reserved space jumps from 136 KB to 264 KB, and average fragmentation bumps up modestly from 33.3% to 40%. This space does not get recovered by a rebuild, online or not, or a reorg, and – as we’ll see shortly – this is not because the table is too small to benefit.

Note: this is true even in the most recent builds of SQL Server 2016 – while more and more operations like this have been improved to become metadata-only operations in modern versions, this one hasn’t been fixed yet, though clearly it could be – again, especially in the case where the column is an IDENTITY column, which can’t be updated by definition.

Read the whole thing.  The clustered key scenario (which will be later in the series) is a bit more interesting to me, as that would be a more common use case for identity values.

Related Posts

External Memory Pressure In SQL Server 2019 On Linux

Anthony Nocentino walks us through memory pressure in SQL Server on Linux: Now in SQL Server 2017 with that 7GB program running would cause Linux to need to make room in physical memory for this process. Linux does this by swapping least recently used pages from memory out to disk. So under external memory pressure, let’s look […]

Read More

Automating Azure SQL Database Scaling

Arun Sirpal shows how to use Azure Logic Apps to auto-scale Azure SQL Database: When I was presenting my Azure SQL Database session at DataRelay (used to be SQLRelay) I was asked (over coffee) about auto scaling capabilities. Quite simply there is nothing out of the box to achieve this. The idea of auto scaling […]

Read More

Categories

February 2016
MTWTFSS
« Jan Mar »
1234567
891011121314
15161718192021
22232425262728
29