Make activity search properly use GIN indexes

The original approach to search in GIN indexes is to use
`to_tsvector(text)` in the WHERE clause of the query. According to
postgres docs [pdoc], this method does not make use of the index,
while `to_tsvector(config, text)` does. This commit changed the
query to use the two-argument `to_tsvector()`.

[pdoc]: https://www.postgresql.org/docs/12/textsearch-tables.html

To obtain the search config in use, we make a query to the db first.
The `::regconfig::oid` hack is needed because Postgrex does not support
regconfig type directly [postgrexbug]. I use the conversion from and to
`oid` instead of `text` because I tested in the actual DB and querying
using the conversion via `text` is slow just as the one-argument
`to_tsvector()` variant.

[postgrexbug]: https://github.com/elixir-ecto/postgrex/issues/502

Backport of: https://git.pleroma.social/pleroma/pleroma/-/merge_requests/3519

Closes: https://git.pleroma.social/pleroma/pleroma/-/issues/2758
This commit is contained in:
Tusooa Zhu 2021-08-27 21:43:50 -04:00 committed by Haelwenn (lanodan) Monnier
parent 53b0dd4ecc
commit bd0eb1c675
No known key found for this signature in database
GPG key ID: D5B7A8E43C997DEE
2 changed files with 17 additions and 2 deletions

View file

@ -28,6 +28,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
- Mastodon API: Activity Search fallbacks on status fetching after a DB Timeout/Error
- Mastodon API: Fix crash in Streamer related to reblogging
- AdminAPI: List available frontends when `static/frontends` folder is missing
- Make activity search properly use language-aware GIN indexes
## 2.4.0 - 2021-08-08

View file

@ -65,10 +65,17 @@ defmodule Pleroma.Activity.Search do
end
defp query_with(q, :gin, search_query, :plain) do
%{rows: [[tsc]]} =
Ecto.Adapters.SQL.query!(
Pleroma.Repo,
"select current_setting('default_text_search_config')::regconfig::oid;"
)
from([a, o] in q,
where:
fragment(
"to_tsvector(?->>'content') @@ plainto_tsquery(?)",
"to_tsvector(?::oid::regconfig, ?->>'content') @@ plainto_tsquery(?)",
^tsc,
o.data,
^search_query
)
@ -76,10 +83,17 @@ defmodule Pleroma.Activity.Search do
end
defp query_with(q, :gin, search_query, :websearch) do
%{rows: [[tsc]]} =
Ecto.Adapters.SQL.query!(
Pleroma.Repo,
"select current_setting('default_text_search_config')::regconfig::oid;"
)
from([a, o] in q,
where:
fragment(
"to_tsvector(?->>'content') @@ websearch_to_tsquery(?)",
"to_tsvector(?::oid::regconfig, ?->>'content') @@ websearch_to_tsquery(?)",
^tsc,
o.data,
^search_query
)