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>Chapter 55. How the Planner Uses Statistics</H1
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>   This chapter builds on the material covered in <A
HREF="using-explain.html"
>Section 14.1</A
> and <A
HREF="planner-stats.html"
>Section 14.2</A
> to show some
   additional details about how the planner uses the
   system statistics to estimate the number of rows each part of a query might
   return. This is a significant part of the planning process,
   providing much of the raw material for cost calculation.
  </P
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>   The intent of this chapter is not to document the code in detail,
   but to present an overview of how it works.
   This will perhaps ease the learning curve for someone who subsequently
   wishes to read the code.
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