Updating statistics sql server 2016
Updating statistics sql server 2016 - bdsmdating ru
We can use the new internal dynamic management function to figure out how statistic pages are organized with incremental statistics.We have to focus on 3 columns here: node_id, first_child and next_cibling columns. The page with the node_id equal to 1 is the final statistic page we’ve seen earlier by using DBCC SHOW_STATISTICS.
Database administrators who use partitioning with version older than SQL Server 2014 know what I mean.Besides, adding a new partition that does not modify more than 20% of the total rows will not issue an automatic update statistic operation and no information about it will not be available.Fortunately incremental statistics changes the story here.This page contains the total number of rows in the big Transaction History table (column rows = 46895292).We can notice that each partition, easily identifiable by the left and right boundaries, has its own page statistic (node_id 3 to 9).The latter is more reliable with partitioned tables because in this case we have to deal with skewed data but requires more time (and more resources) because SQL Server have to read all the table records.
With big partitioned tables we talk about potentially many hours.
Using incremental statistics it is possible to update only one or several partitions as necessary.
The information is then gathered or merged with existing information to create the final statistic. During my tests I will use a modified transaction history table in the Adventure Works2012.
We will partition the big Transaction History table as following: … We retrieve the same information as the older versions.
In fact we’re trying to read statistic data from the final statistic. Note here that the final statistic can have a maximum of 200 steps.
The update operation is triggered when the number of rows reaches 20% of the total existing rows 500 rows.