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  3. Improving Query Performance in PostgreSQL

Exercise

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Hawaii is home to many volcanoes. One volcano, Kīlauea has been erupting nearly continuously since 1983. The spewing volcanic smog (vog) is high in sulfur dioxide (SO2) and results in poor air quality. In fact, based on the count of good or moderate air quality days over 10 years (2008 to 2018), Hawaii has the worst air quality of any state.

In this exercise, you will look at the main air pollutant on poor air quality days, focusing on SO2 . You will compare the cost estimate between a query with an index on the pollutant column and a query without an index.

Instructions 1/3

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  • 1

    Find the records with poor air quality by using the category column to filter out Good air quality days in Hawaii.

  • 2

    Add a SO2 (sulfur dioxide) defining_parameter filter and note the overall query cost estimate.

  • 3

    Create an index on the defining_parameter. Is the query cost estimate smaller than the prior query's estimate?