Viewing and estimating with statistics

The statistics information collected for each table is easiest to see using the pg_stats view. The amount of information it returns is a bit overwhelming though, and not well suited to the standard display format. The following script is named in the book's file set, and it tries to display the statistics information for a particular table (with an optional database too) in a way that makes the information as readable as possible:

#!/bin/bashif [ -z "$1" ]; then  echo "Usage: table [db]"  exit 1fiTABLENAME="$1"if [ -n "$2" ] ; then  DB="-d $2"fiPSQL="psql $DB -x -c "$PSQL "SELECT  tablename,attname,null_frac,avg_width,n_distinct,correlation, most_common_vals,most_common_freqs,histogram_bounds ...

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