Kevin Hsiao kevinisbest

## Master-worker.go
package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"
)

## notes.md

      
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                ian-whitestone
                / notes.md
            
            
              Last active
              March 1, 2023 01:45
            
              
                Best practices for presto sql
              
          
    Presto Specific


Don’t SELECT *, Specify explicit column names (columnar store)
Avoid large JOINs (filter each table first)

In PRESTO tables are joined in the order they are listed!!
Join small tables earlier in the plan and leave larger fact tables to the end
Avoid cross joins or 1 to many joins as these can degrade performance


Order by and group by take time

only use order by in subqueries if it is really necessary


When using GROUP BY, order the columns by the highest cardinality (that is, most number of unique values) to the lowest.
	package main

	import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"
	)