As the docs you quote indicate, you can’t use $lookup on a sharded collection. So the best practice workaround is to perform the lookup yourself in a separate query. Perform your aggregate query. Pull the “localField” values from your query results into an array, possibly using Array#map. Perform a find query against the “from” collection, … Read more
By default, Elasticsearch will re-assign shards to nodes dynamically. However, if you’ve disabled shard allocation (perhaps you did a rolling restart and forgot to re-enable it), you can re-enable shard allocation. # v0.90.x and earlier curl -XPUT ‘localhost:9200/_settings’ -d ‘{ “index.routing.allocation.disable_allocation”: false }’ # v1.0+ curl -XPUT ‘localhost:9200/_cluster/settings’ -d ‘{ “transient” : { “cluster.routing.allocation.enable” : … Read more
The best approach for sharding MySQL tables to not do it unless it is totally unavoidable to do it. When you are writing an application, you usually want to do so in a way that maximizes velocity, developer speed. You optimize for latency (time until the answer is ready) or throughput (number of answers per … Read more