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POEffectively COUNTing and SUMing on a large inner join
 

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    <p>Please consider the following case (simplified for the sake of the question):</p> <p>I have the following tables in the SQL Server 2012 database:</p> <pre><code>Parent_Table Id | Parent table fields ----+-------------------- 1 | ... 2 | ... 3 | ... ... Child_Table Id | ParentId | Child table fields ----+----------+------------------- 1 | 2 | ... 2 | 1 | ... 3 | 1 | ... 4 | 3 | ... 5 | 2 | ... ... Big_Table Id | ChildId | Value | Status | Other fields --------+----------+--------|--------------------- 1 | 12 | 672 | Closed | 2 | 23 | 133 | Closed | 3 | 7 | 2611 | Open | 4 | 14 | 84 | Closed | ... 1295769 | 23 | 458 | Closed | 1295770 | 18 | 1046 | Open | 1295771 | 7 | 8 | Open | </code></pre> <p>The Child and Parent tables are relatively small (roughly 100 Parent entries and 5 Child entries per parent) and their entries are inserted or deleted only a few times a day.</p> <p>The "Big Table", on the other hand, is growing fast (100 entries per second, for the sake of discussion), and the status of rows becomes Closed after a while (think of client sessions, which is the actually the case here).</p> <p>I need to periodically (every few seconds) provide the number of Big_Table rows and the sum of the Big_Table.Value column <strong>for a specified Parent.Id</strong> - a different one every time.</p> <p>I suspect that the straightforward implementation (using inner joins etc.) might be extremely inefficient, and better solution may include additional tables, a table of counters of some sort or I should just implement this in my service code (?!) and take care of persistence somehow.</p> <p>What would be the "right" (efficiency-wise) way of implementing the above? A solution which handles additional levels of parents/children would be the best one. </p>
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    1. COMake sure you have the correct indexes on the table, maybe partition it, then just use a join. SQL can handle a large number of rows easily if you have your database designed correctly.
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    2. CO@cadrell0 - Obviously the indexes are a must (despite the extra cost upon insertions), but I'm not sure it's going to be enough in this case.
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    3. CODid you consider an indexed view?
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