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MVCC – the part of PostgreSQL we hate the most (2023)

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366 points virtualwhys | 3 comments | 20 Oct 24 15:30 UTC | HN request time: 0.588s | source
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srcreigh ◴[21 Oct 24 02:59 UTC] No.41900307[source]▶
It’s really annoying to see people write that Postgres has a “primary index” and “secondary indexes”. No. That’s not what those words mean. Every index in Postgres is a secondary index.
replies(1): >>41903808 #
sgarland ◴[21 Oct 24 13:12 UTC] No.41903808[source]▶
You’re not technically wrong, but even Postgres’ docs [0] use the term Primary Key.

[0]: https://www.postgresql.org/docs/current/ddl-constraints.html

replies(1): >>41904432 #
srcreigh ◴[21 Oct 24 14:16 UTC] No.41904432[source]▶
Postgres primary key indexes are not primary indexes.
replies(1): >>41905138 #
1. sgarland ◴[21 Oct 24 15:20 UTC] No.41905138[source]▶
I know that, I’m saying that it’s a fairly pedantic argument when even their own docs use the term loosely.
replies(2): >>41906024 #>>41909511 #
2. j16sdiz ◴[21 Oct 24 16:54 UTC] No.41906024[source]▶
"Primary Key" is the term in SQL standard. The url you linked is in "Part II: The SQL Language"
3. jeltz ◴[21 Oct 24 23:09 UTC] No.41909511[source]▶
Primary keys are primary indexes are two mostly unrelated terms.