Why GIN and not GiST?

[ccleve]

I'm just starting to get into Postgres development. I'm trying to understand index structures and how to extend them. I noticed that you folks are also the ones that maintain the Postgres GiST code. Why did you choose to base RUM on GIN instead of GiST?

Sorry for the newbie question -- I'm not familiar with the Postgres code base yet. I did find some (short) references on creating new GiST indexes, but nothing on GIN, and I'm finding the code hard to follow.

[obartunov]

On Sat, Oct 19, 2019 at 7:58 PM Chris Cleveland ***@***.***> wrote: I'm just starting to get into Postgres development. I'm trying to understand index structures and how to extend them. I noticed that you folks are also the ones that maintain the Postgres GiST code. Why did you choose to base RUM on GIN instead of GiST? Sorry for the newbie question -- I'm not familiar with the Postgres code base yet. I did find some (short) references on creating new GiST indexes, but nothing on GIN, and I'm finding the code hard to follow.

You are welcome, Chris ! GIN has a better scalability than GiST for full text search.

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[ccleve]

Can you give a few more details? I haven't been able to find good documentation on the underlying file formats of the different index types. Do you know of any docs that explain how GIN indexes are formatted internally, and how to modify them?

[obartunov]

On Mon, Oct 21, 2019 at 5:13 PM Chris Cleveland ***@***.***> wrote: Can you give a few more details? I haven't been able to find good documentation on the underlying file formats of the different index types. Do you know of any docs that explain how GIN indexes are formatted internally, and how to modify them?

src/backend/access/gin/README —

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[ccleve]

Thank you, perfect.

[ccleve]

At the very bottom of the README, there is this comment:

Distant future:

• Replace B-tree of entries to something like GiST

Can you explain a bit more?

[obartunov]

Фд

On Mon, Oct 21, 2019 at 9:44 PM Chris Cleveland ***@***.***> wrote: At the very bottom of the README, there is this comment: Distant future: Replace B-tree of entries to something like GiST Can you explain a bit more?

Read https://www.pgcon.org/2014/schedule/events/696.en.html Also, I have some talks about indexing http:https://www.sai.msu.su/~megera/postgres/talks/ You can use google translate and read 6 papers about indexes in postgres https://habr.com/ru/company/postgrespro/blog/337502/

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