Previewing a row-oriented table
When working with new tables, it is common to SELECT * to preview the data. However, selecting all the rows from a large table using row-oriented storage is resource intensive and slow. A quick optimization trick is to limit the number of rows returned.
You will be working with air quality data from the United States. This data lives in a Postgres database using row-oriented storage. Familiarize yourself with daily_aqi by previewing the data. First, select all records. Then limit the results to improve speed.
Use the EXPLAIN command to quantify the effect of limiting the rows.
Cet exercice fait partie du cours
Improving Query Performance in PostgreSQL
Exercice interactif pratique
Essayez cet exercice en complétant cet exemple de code.
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SELECT *
FROM daily_aqi;