How does query parameters work under the hood?

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Asked 3 years, 3 months ago

Modified 3 years, 3 months ago

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I thought about how can it work under the hood and I came with an idea

Db engine receives query with parameters and also defined values of those parameters
SQL is being parsed into syntax tree like that

After parsing values of parameters are inserted into tree to places where associated with them parameters are
Query is being executed without another parsing

Is it at least conceptually true?

eckes

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asked Feb 13, 2019 at 11:10

Joelty

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That depends on the actual database engine beeing used, however I would agree that an efficient engine would not do string replacement and parse the query again (but I am also sure there are engines which are not so sophisticated). For Oracle there is a soft/hard parse destination and parameter binding is one of the phases after that.
– eckes
Feb 13, 2019 at 11:20
Pro SQL Server Internals, Microsoft SQL Server 2012 Internals
– McNets
Feb 13, 2019 at 11:35

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