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Primary and secondary subclusters - question about node counts and sharding

Deb_ChatignyDeb_Chatigny Administrator
edited April 2020 in General Discussion

Do the primary and secondary subclusters need to have the same node count and the same sharding footprints?
@dsprogis @ybei

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  • dsprogisdsprogis Employee

    Shard count is an attribute of the database, once set, it never changes. Subclusters are most efficient when the shards are evenly distributed across nodes because the query will only run as fast as the slowest node (the node with the most shard subscriptions). Thus, the number of nodes should be an factor of the shard count. A shard count of 12 is good because its factors are 1, 2, 3, 4, 6, and 12 which gives you a lot of options. Importantly, because shard count establishes the maximum number of nodes that will participate in a query, you should size it high enough for your most complex, long running queries. This is the case regardless of whether the subcluster is primary or secondary.

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