internal/postgres: change search tokens

Change the way that the Postgres ts_vector (list of search tokens) is computed.

- Use the path_tokens text configuration when creating the tsvector for the path.

- Construct sections B and C of the search document by combining the synopsis
  part of the README. Parts of this processing are:

  - Extract only the text of a markdown README, to remove images and
    other extraneous information.

  - Add alternatives to certain words in the synopsis and README. For
    example, add "postgresql" whenever we see "postgres".

- Modify the ts_rank call in the code to use a B weight of 1.

- Change the call to the database search function so that it invokes
  the function that has a B weight of 1.

These changes will require re-computing the
search_documents.tsv_search_tokens column. That should be done after
these are deployed.

Change-Id: Ib81601326f11efd81c8bc733694a000eccecf12b
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/705958
Reviewed-by: Julie Qiu <julieqiu@google.com>

0 files changed, 0 insertions, 0 deletions