Default behavior when querying over a sharded index

[s-fletcher]

If a facet is configured to use shards, the default behavior should be to query every shard if none is specified.

Some positive outcomes:

• Minimizes code when querying all shards (as shown below)
• Removes anti-pattern to define a shard count in some configuration file to reference outside of facet
• Allows previous pattern to prevent breaking changes

Before

const promises = [];
for(let i = 0; i < SHARD_COUNT; i++) {
    promises.push(Facet.query({ partition }, i).list());
}
const results = await Promise.all(promises);
const records = results.map((result) => result.records).flat();

After

const { records } = await Facet.query({ partition }).list();

[s-fletcher]

How we handle cursors and limits is going to be a difficult problem here. I'm currently brainstorming some ideas.

[s-fletcher]

Here's an idea.

The idea is to iterate through the group of shards like so and keep track of the position of the last request with a new cursor storing this information.

There is still a limitation that isn't immediately clear. The results will not be sorted due to the randomness of how records are sharded. This might prompt us to create a new function to only be used in sharded facets such as queryShards instead of query. But this feels wrong.

Maybe the solution here is to not even have Faceteer offer this? Instead, to communicate this solution, but let the developer implement it.