#NestedLoop

Joins can scale and SQL optimizers have great algorithms and data structures. To be efficient, a join must have fast access to the inner table, with a sort or hash structure. An existing one (sharding, index) or built on the fly (in work memory). Let's look at join methods🧵👇

If they are not sorted and the join condition is an equality predicate, the smallest is hashed to accelerate the lookup into the inner table. This is a #HashJoin:

If there's already a sorted structure for the inner table, like an index, and not a lot of outer rows, the lookup uses the index for each outer row. This is a #NestedLoop:

Sebuah lagu tentang Nested Loop dan Skrip Politik di tempat kerja .. 🎵 MNEMONIKK - If-Else Do-While (Alternative Version) #Electroclash #nestedloop #loop #politik

┏┓ ┃┃╱╲ in ┃╱╱╲╲ this ╱╱╭╮╲╲ house ▔▏┗┛▕▔ we ╱▔▔▔▔▔▔▔▔▔▔╲ Wash our hands before and after we wash our hands ╱╱┏┳┓╭╮┏┳┓ ╲╲ ▔▏┗┻┛┃┃┗┻┛▕▔

@HealthIT_Policy That's a never-ending hand-washing spiral from the beginning of time until the end of time! #nestedloop

Can you figure out how many steps should the duck make? Leave your answer in the comment! #nestedloop #codinggame #STEMeducation #STEMinSchools

I don’t understand why people take screen shots of tweets and post them on Instagram

@Mike_Stelzner Because it’s ironic? #NestedLoop

നെസ്റ്റഡ് ലൂപ്പിൽ നിന്നും പുറത്തു വരാൻ നെസ്റ്റ് പൊളിക്കേണ്ടി വരുമോ  #loop  #nestedloop

4th grade geniuses #collaborating on solving a #nestedloop puzzle! @TeachCode @TeachMrReed @CarstarphenMJ @apsupdate @APSInstructTech

@HPE_DE Wahnsinn! Kann man damit auch einen #NestedLoop im #Cybermode laufen lassen? 😍

Professor: "What do you call a for loop within a for loop within a for loop?" Some kid: "Inception" #nestedloop #java #AppDev