country code synonyms

[missinglink]

branched from https://github.com/pelias/schema/pull/471 please merge that PR first, see diff

This PR:

• adds an iso3166 country code synonyms mapping file
• enables the synonyms file for the peliasAdmin and peliasIndexOneEdgeGram analyzers.

This work solves the issue outlined in https://github.com/pelias/schema/pull/469, however it could come with some unwanted side-effects, so we should discuss them before merging..

Ideally these synonyms would only be applied to the parent.country_a field and not other peliasAdmin fields such as parent.region (for example).

In order to accomplish that we would need to do a bit of refactoring, this may be preferable to avoid synonyms like ST,STP from this new file conflicting with regions prefixed with 'Saint', for instance.

Each of the address_parts.*, name.* etc fields currently have their own analyser, but the parent.* fields all share a common analyser, it may be time to give each parent.* field it's own analyser so they can be configured independently.

One other issue I noticed when developing this is that the admin partial uses "search_analyzer": "peliasAdmin" when it should really use "search_analyzer": "peliasQuery", this means that synonyms are being applied at both query-time and search-time.

For the parent.*.ngram fields we index with "analyzer": "peliasIndexOneEdgeGram", which means that the synonyms will also be added to the name.* fields, this could be avoided if we also had individual ngram analyzers for each of these sub-fields which were different from the main peliasIndexOneEdgeGram analyzer.

Let's discuss on a call..

[missinglink]

note: we may want to add some non-standard synonyms such as UK,GB

[orangejulius]

I ran a quick WOF-only build with this PR, and can confirm that it's enough to make the city autocomplete test in https://github.com/pelias/acceptance-tests/pull/537 flip to passing

[orangejulius]

Just repeating and expanding on my comment in https://github.com/pelias/schema/pull/471#issuecomment-772656955 over here:

It seems like we want to keep the basic structure of this PR, where we use synonyms to handle either the 2 or 3 letter variants of country codes, with two changes:

• first, to avoid breaking the structured endpoint, it seems like we can do away with changing anything about the field mappings. We can keep the parent.*_a fields on the standard admin mapping. If we need to add any tests to verify the scoring aspects of keeping field lengths and token positions enabled, lets do so
• second, and less important I guess, but we might as well: we only need to include synonyms for the country abbreviations where the 2 letter code isn't a prefix of the 3 letter code. The majority of them are prefixes of each other, so that will keep the synonym list smaller. Just in general, the idea of keeping the synonym list more targeted is appealing, even if it doesn't have any immediately obvious impact.

Otherwise, looks like this will fix a nice case for us and shouldn't really break anything else 👍

[missinglink]

superseded by https://github.com/pelias/schema/pull/473