hash-join-execution-internals 
SQL Performance
NOVEMBER 4, 2021
First introduced in SQL Server 2017 Enterprise Edition, an adaptive join enables a runtime transition from a batch mode hash join to a row mode correlated nested loops indexed join (apply) at runtime. For brevity, I’ll refer to a “correlated nested loops indexed join” as an apply throughout the rest of this article.
The Netflix TechBlog
SEPTEMBER 29, 2022
Notice the three Cosmos subsystems: Optimus, an API layer mapping external requests to internal business models, Plato, a workflow layer for business rule modeling, and Stratum, the serverless layer for running stateless and computational-intensive functions. We then codify this prefix as a Redis hash tag.
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The Netflix TechBlog
JULY 20, 2020
The application is a combination of neural embeddings , which encode the semantic information in words and sentences, and locality sensitive hashing , which efficiently assigns approximately nearby items to the same buckets and faraway items to different buckets. Erica Sinclair and locality-preserving hashing What about clustering?
SQL Performance
MARCH 8, 2021
SQL Server 2014 SP2 and later produce runtime (“actual”) execution plans that can include elapsed time and CPU usage for each execution plan operator (see KB3170113 and this blog post by Pedro Lopes). There are important differences between row mode and batch mode execution, as well as tricky issues with row mode parallelism.
SQL Performance
AUGUST 23, 2019
In traditional row-mode execution plans, SQL Server may introduce a Bitmap operator as part of performing early semi join reduction before a parallel hash or merge join. The bitmap is constructed from the build input, and used to filter rows on the probe input before they reach the join. Background.
SQL Performance
NOVEMBER 22, 2019
To be accessed more than once, the spool must appear on the inner side of a nested loops join operator. That means that the join needs to be an apply , not a nested loops join. For the difference between the two, please see my article Apply versus Nested Loops Join. Product AS P JOIN Production. Notable features.
Percona
JANUARY 4, 2023
At which execution stage is a query taking time, or how much time will an alter command will take? Stage – Instrument starting with ‘stage’ provides the execution stage of any query like reading data, sending data, altering table, checking query cache for queries, etc. This is being done by hashing algorithms.
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