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9 gru 2015 · There are several considerations when writing a query using the IN operator that can have an effect on performance. First, IN clauses are generally internally rewritten by most databases to use the OR logical connective. So col IN ('a','b','c') is rewritten to: (COL = 'a') OR (COL = 'b') or (COL = 'c').
I got a complex SQL query where the IN statement could contain over 50,000 ids. The query timeouts after 20-30 seconds and the only way to resolve this issue is to change the query to return the results hopefully in a no more than 1-2 seconds. Increasing the timeout is NOT an option. Create table:
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This tip will look at the pros and cons of each method and use a repeatable methodology to determine which method will offer the fastest performance. The best part about this tip is that the performance comparison methodology can be applied to any TSQL coding situation!
For your first two queries, on SQL Server, the query optimizer will order the values for you before going to the database. You can confirm this by looking at the seek predicate for the execution plan of each of those queries.
10 gru 2021 · If you materialize UF_WORKFLOW_INSTANCE to a temp table first and cast the process_instance field to NVARCHAR(64) when you insert it into the temp table, then join to that temp table instead, does the performance get better again (even with the IN clause in your query still)?
3 wrz 2024 · Explicitly including an extremely large number of values (many thousands of values separated by commas) within the parentheses, in an IN clause can consume resources and return errors 8623 or 8632. To work around this problem, store the items in the IN list in a table, and use a SELECT subquery within an IN clause.
