REF: Compression and its Effects on Performance

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I want to remember this study by Erin Stellato.

The summary:

If you’re in an OLTP system, you don’t want to return that many rows, so the tests here should give you an idea of how compression may affect performance. If you’re in a data warehouse, then you will probably see higher duration along with the higher CPU when returning large data sets. While the COMPRESS function provides significant space savings compared to page and row compression, the performance hit in terms of CPU, and the inability to index the compressed columns due to their data type, make it viable only for large volumes of data that will not be searched.

Posted in: Performance, SQL

REF: Page allocation changes in Sql Server 2016

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While searching for information about MIXED_PAGE_ALLOCATION in SQL 2016+ and TF1118 I came across great examples about Page allocation changes in Sql Server 2016 here

Summary: For user databases in the versions of Sql Server older than 2016, the first 8 data pages were allocated from the mixed extent and next pages from uniform extent. In Sql Server 2016 even the first eight data pages were allocated from the uniform extent. Below image summaries this page allocation mechanism comparison between Sql Server 2016 and older versions of Sql Server

Posted in: Configuration, Documentation

PowerShell: What jobs are currently executing, running now?

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# ------------------------------------------------------------------------------------------------------------------------
# What jobs are currently executing, running now? RUNNING JOBS


$ExclusionList = @('SQLEXT1')#   @() # # @() #  @() # 
#
$RunningJobs = Get-SQLExecutingJobs -AllServersList $AllServersList -ExclusionList $ExclusionList -ErrorAction Continue # -Verbose -WarningAction SilentlyContinue

# Summarize
$RunningJobs |Sort-Object ServerName |
    Select-Object RunDateTime, @{n="Duration   ";e={ ("{0:dd\:hh\:mm\:ss}" -f (NEW-TIMESPAN –Start $_.RunDateTime –End (GET-DATE))) }},
        ServerName, JobName,current_execution_step,last_run_date,last_run_time |
            Format-Table -autosize
Posted in: PowerShell, Reports