Change log

Change log

This site has different types of readers. Those that come here to quickly look up something, using it as the reference this is. And those that read everything, or at least the pages they consider interesting, using it as a source of knowledge in addition to books, blogs, conferences, etc.

Especially the second type of reader might want to know when something changed. That’s what this page is for. Here you will find a full log of all changes. Most recent first.

July 18, 2020

Updated pages:

  • Compute Scalar: Added remarks about its fixed cost estimates to the list of Operator Properties.

July 17, 2020

New pages:

  • Compute Scalar: New page with the description of the Compute Scalar operator.

Updated pages:

  • Added link to the Compute Scalar page on the Operator list
  • Common Properties: Added pointer to Compute Scalar for the generic description of functions in the Defined Values

June 20, 2020

Updated pages:

  • Common Properties: Added lots of detail and better explanation for a variety of properties.
  • All operator pages:
    • Switched order of old and new SSMS icon; and added Plan Explorer icon on operator page that didn’t have it yet.
    • Added a marker to properties that are also discussed on the Common Properties page.
    • Clarified wording and fixed typos for several properties.
  • Hash Match: Added extra information on Estimated CPU Cost and Estimated I/O Cost
  • Nested Loops: Added extra details to the description of the prefetching process.

June 15, 2020

New pages:

  • Table Scan: New page with the description of the Table Scan operator.

Updated pages:

  • Added link to the Table Scan page on the Operator list
  • Fixed small typos and language errors in the property list on several pages.

May 20, 2020

New pages:

  • RID Lookup: New page with the description of the RID Lookup operator.

Updated pages:

  • Key Lookup: Added description of unexpected behavior of Estimated Number of Rows, Estimated Number of Rows Per Execution, and Estimated Number of Rows for All Execution properties when a Predicate property is present and corrected the description of the Forced Index
  • Added link to the RID Lookup page on the Operator list page, and on a few other pages.

April 21, 2020

Updated pages:

  • Plan properties: Added two new sub-properties of the MemoryGrantInfo property, both related to Memory Grant Feedback; added a link to a list of documented values for the NonParallelPlanReason property, and corrected a typo.

April 19, 2020

New pages:

  • Key Lookup: New page with the description of the Key Lookup operator.

Updated pages:

  • Index Seek: Corrected a minor copy/paste error.
  • Added link to the Key Lookup page on the Operator list page, and on a few other pages.

April 12, 2020

Updated pages:

  • Generic information: Rewrote a large part of the page and made several small changes, to use proposed new terminology for execution plans instead of the confusing old terminology; also added a note about improved handling of overly long property values in the popup window on newer versions of Management Studio.
  • Multiple pages: Changed to use proposed new terminology for execution plans instead of the confusing old terminology. Also made some minor other changes on those pages.
  • Columnstore Index Scan: Removed Number of Rows Read from the property list; it was there in error, this operator doesn’t have this property. Also changed the description of the Predicate property to not refer to Number of Rows Read.
  • Plan Properties: Added descriptions for the sub-properties of the QueryTimeStats property; added new information for the RetrievedFronCache property; fixed some formatting issues.

April 9, 2020

Updated pages:

  • Common Properties: Updated with the improvements in how Management Studio 18.5 displays actual and estimated row count. Also added Estimated Data Size (that I had overlooked before).

July 12, 2019

New pages:

Updated pages:

  • Index Scan: Added reference to Clustered Index Scan in opening text to prevent possible misunderstandings (thanks, Nico!).
  • Index Seek: Added the Seek Predicates property to the table of properties; corrected a mistake in the flowchart (thanks, Josh!); corrected a typo (thanks, Nicky!); corrected the spelling of a property in the main text.
  • Added link to the Clustered Index Seek page on the Operator list page, and on a few other pages.

July 8, 2019

New pages:

  • Index Seek: New page with the description of the Index Seek operator.

Updated pages:

  • Index Scan: Added some additional details about Actual Rows Read property, and added the Scan Direction property that I had previously forgotten.
  • Added link to the Index Seek page on the Operator list page, and links to both Index Seek and Index Scan on the Common Properties

June 10, 2019

New pages:

Updated pages:

  • Index Scan: Added note about columnstore and memory-optimized indexes in discussion of Parallel Page Supplier, added note about rowgroup elimination in description of Predicate
  • Clustered Index Scan: Added note about rowgroup elimination in description of Predicate property, corrected reference to Parallel Page Supplier in description of Parallelism aware implicit property.
  • Added link to the Columnstore Index Scan page on the Operator list page, and on the Index Scan and Clustered Index Scan pages.

June 9, 2019

New pages:

Updated pages:

  • Index Scan: Added handling of deltastore rowgroups to description of columnstore index scan behavior; added description of memory-optimized nonclustered hash index scan behavior; and fixed a few minor issues.
  • Added link to the Clustered Index Scan page on the Operator list page (and a few other pages).

June 2, 2019

New pages:

  • Index Scan: New page with the description of the Index Scan operator.

Updated pages:

March 18, 2019

New pages:

  • Collapse: New page with the description of the Collapse operator.

Updated pages:

  • Split: Huge rewrite after I found out that there is not always an action column in the input. I thought it needed this action column to determine how to treat each row, now I have removed that theory and replaced it with a few alternatives.
  • Added link to the Collapse page on the Operator list and Split pages.

February 21, 2019

Updated pages:

  • Added link to the Split page on the Operator list page (I apparently forgot to save this change when I first made it on February 20).

February 20, 2019

New pages:

  • Split: New page with the description of the Split operator.

Updated pages:

February 10, 2019

Updated pages:

  • Hash Match: Added some additional information on whether the build phase runs during Init() processing or during the GetNext() processing (thanks, Martin).
    Also fixed a minor copy/paste error in a subheading.

February 5, 2019

Updated pages:

  • Operator list: Added a column for the new icons as used in Plan Explorer (thanks, Aaron).
  • Assert: Fixed a mistake in the flowchart, and a copy/paste error in the text (thanks, Thierry).

February 2, 2019

Updated pages:

  • Plan Properties: Added a description for the “SecurityPolicyApplied” property. Thanks to Kendra Little for blogging about this, and to Thierry van Durme for sending me the link to that post!

January 31, 2019

Updated pages:

  • Index Spool: Added a description of the “limited parallelism awareness” of this operator, and made two minor single-word changes. Thanks to Erik Darling for sharing the execution plan that made me discover this!

January 14, 2019

Updated pages:

January 3, 2019

New pages:

  • Adaptive Join: New page with the description of the Adaptive Join operator.

Updated pages:

  • Added link to the Adaptive Join page on the Operator list page (and a few other pages).
  • Hash Match: Corrected a mistake in the list of implicit properties (two join types were erroneously listed as order-preserving).

December 21, 2018

New pages:

  • Bitmap: New page with the description of the Bitmap operator.

Updated pages:

November 18, 2018

New pages:

  • Index Spool: New page with the description of the Index Spool operator.

Updated pages:

  • Added link to the Index Spool page on the Operator list page (and a few other pages).
  • Table Spool: Correction to the “Order-preserving” property. Also fixed a few typos.
  • Added or corrected links to other pages on several pages.

November 15, 2018

Updated pages:

  • Table Spool: Small correction to the flowchart in the “Actual Logic” section.

November 13, 2018

Updated pages:

  • Table Spool: Corrected the links for the “operator properties” and “implicit properties” tables (thanks, Jan!).

November 11, 2018

Updated pages:

  • Updated the Common properties and Plan properties pages with properties found in the last Cumulative Update of SQL Server. (SQL Server 2017, CU12). Some of these are new, others I had originally overlooked.

November 7, 2018

New pages:

  • Table Spool: New page with the description of the Table Spool operator.

Updated pages:

  • Added link to the Table Spool page on the Operator list page (and a few other pages).

October 27, 2018

Changed the RSS feed to include all pages on this site instead of only the blog posts.

September 24, 2018

Updated pages:

September 10, 2018

Updated pages:

  • Home page: Replaced link to Grant Fritchey’s execution plans book to reference the third edition.

July 30, 2018

New pages:

  • Assert: New page with the description of the Assert operator.

Updated pages:

June 27, 2018

New pages:

  • Segment: New page with the description of the Segment operator.

Updated pages:

  • Added link to the Segment page on various other pages.

June 4, 2018

New pages:

  • Plan properties: Formerly a section on the generic information page, now a page of its own.

Updated pages:

Navigation:

  • Added menu with direct access to relevant pages (thanks, Joshua!)

June 2, 2018

New pages:

Updated pages:

  • Generic information: Fixed a copy/paste error (thanks, Richard!); added additional information to plan property RetrievedFromCache; added plan properties StatementParameterizationType and StatementSqlHandle.
  • Homepage: Added link to change log.

May 31, 2018

New pages:

 

 

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