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This adds support for using PGroonga to back the Zulip full-text search feature. Because built-in PostgreSQL full text search doesn't support languages that don't put space between terms such as Japanese, Chinese and so on. PGroonga supports all languages including Japanese and Chinese. Developers will need to re-provision when rebasing past this patch for the tests to pass, since provision is what installs the PGroonga package and extension. PGroonga is enabled by default in development but not in production; the hope is that after the PGroonga support is tested further, we can enable it by default. Fixes #615. [docs and tests tweaked by tabbott]
108 lines
3.7 KiB
Markdown
108 lines
3.7 KiB
Markdown
# Full-text search
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Zulip supports full-text search, which can be combined arbitrarily
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with Zulip's full suite of narrowing operators. By default, it only
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supports English text, but there is an experimental
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[PGroonga](http://pgroonga.github.io/) integration that provides
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full-text search for all languages.
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The user interface and feature set for Zulip's full-text search is
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documented in the "Search help" documentation section in the Zulip
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app's gear menu.
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## The default full-text search implementation
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Zulip's uses [PostgreSQL's built-in full-text search
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feature](http://www.postgresql.org/docs/current/static/textsearch.html),
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with a custom set of English stop words to improve the quality of the
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search results.
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We use a small extension,
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[tsearch_extras](https://github.com/zulip/tsearch_extras), for
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highlighting of the matching words. There is [some discussion of
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removing this extension, at least as an
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option](https://github.com/zulip/zulip/issues/467), so that Zulip can
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be used with database-as-a-service platforms.
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In order to optimize the performance of delivering messages, the
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full-text search index is updated for newly sent messages in the
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background, after the message has been delivered. This background
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updating is done by
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`puppet/zulip/files/postgresql/process_fts_updates`, which is usually
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deployed on the database server, but could be deployed on an
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application server instead.
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## An optional full-text search implementation
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Zulip now supports using [PGroonga](http://pgroonga.github.io/) for
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full-text search. PGroonga is a PostgreSQL extension that provides
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full-text search feature. PostgreSQL's built-in full-text search
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feature supports only one language at a time (in Zulip's case,
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English). PGroonga supports all languages simultaneously, including
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Japanese, Chinese and so on, all at once. We expect to migrate
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Zulip's full-text search to only support PGroonga once we have tested
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this new extension fully.
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The following processes should be executed as the root user. Run:
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sudo -i
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### How to enable full-text search against all languages
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This section describes how to enable using PGroonga to back the
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full-text search feature.
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* To install PGroonga, add `pgroonga = enabled` in the `[machine]`
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section in `/etc/zulip/zulip.conf`:
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[machine]
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...
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pgroonga = enabled
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And then run as root:
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/home/zulip/deployments/current/scripts/zulip-puppet-apply
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Then, add `USING_PGROONGA = true` in `/etc/zulip/settings.py`:
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USING_PGROONGA = True
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And apply the PGroonga migrations:
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cd /srv/zulip
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./manage.py migrate pgroonga
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Note that the migration may take a long time, and you can't send new
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messages until the migration is finished.
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Once the migrations are complete, restart Zulip:
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su zulip -c /home/zulip/deployments/current/scripts/restart-server
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Now, you can use full-text search against all languages.
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### How to disable full-text search against all languages
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This section describes how to disable full-text search feature based
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on PGroonga.
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If you want to fully remove PGroonga, first you need to remove the
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PGroonga column (as above, this will take a long time and no messages
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can be sent while it is running). If you intend to re-enable PGroonga
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later, you can skip this step (at the cost of your Message table being
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slightly larger than it would be otherwise).
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/home/zulip/deployments/current/manage.py migrate pgroonga zero
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Then, set `USING_PGROONGA = False` in `/etc/zulip/settings.py`:
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USING_PGROONGA = False
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And, restart Zulip:
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su zulip -c /home/zulip/deployments/current/scripts/restart-server
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Now, full-text search feature based on PGroonga is disabled. If you'd
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like, you can also remove the `pgroonga = enabled` line in
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`/etc/zulip/zulip.conf` and uninstall the `pgroonga` packages.
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