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Parallel to serial converter example7/5/2023 ![]() Sadly, there is currently no corresponding hint to force the optimizer to choose a parallel plan. One such query hint is the (over) popular OPTION (MAXDOP 1), which prevents the optimizer from considering plans that use parallelism. ![]() These hints are usually seen as a tool of last resort, because they can make code harder to maintain, introduce extra dependencies, and may prevent the optimizer reacting to future changes in indexing or data distribution. SQL Server provides a number of query and table hints that allow the experienced practitioner to take greater control over the final form of a query plan. This situation often occurs when making an apparently innocuous change to the text of a moderately complex query - a change which somehow manages to turn a parallel plan that executes in ten seconds, into a five-minute serially-executing monster. ![]() This article is for SQL Server developers who have experienced the special kind of frustration that only comes from spending hours trying to convince the query optimizer to generate a parallel execution plan.
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