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Can NULLs Improve your Database Queries Performance? - The Backend Engineering Show
The Backend Engineering Show with Hussein Nasser
English - April 11, 2021 19:10 - 22 minutes - 13 MB - ★★★★★ - 5 ratingsTechnology Homepage Download Apple Podcasts Google Podcasts Overcast Castro Pocket Casts RSS feed
In this episode, we will discuss NULLs in database systems. I’ll go through the following:
What is Null?
NULLs persistence
Whether you store a 0 or 2 billion value in the field 32bit integer field it costs 32 bit
when you store a NULL in 32 bit integer field we save 32 bit but add overheads
When NULLs are naughty
Semantics and inconsistent result
Select count(*). Includes nulls
count(column) ignores nulls
T is NULL returns the null rows
T is NOT NULL returns not null rows
T In (NULL) returns nothing
T not in NULL returns nothing
Some database don’t index nulls
When NULLs are useful
I don’t have value , I don’t wish to provide a birthday
not applicable field for certain use cases but not others fat tables (denormlization)
Fat tables with many columns makes your rows longer which means fewer rows fit in your page (show pic).. NULLs help here .. that are NULL, it yields shorter rows, instead of storing a default 0 value
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