relation_hexedit

#!/bin/bash
#
# relation_hexedit:  Sets generic decile offsets in wxHexEditor cache/registry,
# before opening relation.  Unlike the other convenience scripts, this works
# with any kind of relation, and has no dependency on contrib/pageinspect.

usage() {
  cat <<EOM
  Usage:
  $(basename "$0") relname

EOM
  exit 0
}

[ -z "$1" ] && { usage; }

source ./hexedit.cfg

relname=$1

# Generate 9 points that divide 10 deciles in Go to offsets dialog cache.
# These are offsets into the first segment, not the relation as a whole.
#
# Note that the query will return NULL for very small relations, which leaves
# us without any cached offsets.
if ! OFFSETS=$(psql --no-psqlrc -tA -c "WITH offsets (block_offset) AS (
  SELECT unnest(percentile_cont(array[0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]) WITHIN GROUP (ORDER BY i))::int8 * (2^13)
  FROM
  (SELECT i FROM generate_series(1, LEAST(131071, (SELECT (pg_relation_size('$relname'::regclass) / (2^13))::int4) - 1)) i ) s
),
nums (num, bb_offset) AS (
  SELECT (ROW_NUMBER() OVER()) - 1, block_offset
  FROM
  offsets ORDER BY BLOCK_OFFSET
)
SELECT string_agg('GoToOffset' || num || '=' || bb_offset, chr(10)) FROM nums;")
then
  echo "calculating decile offsets failed"
  exit 1
fi

export OFFSETS
echo "Tip: 'Go to Offset' dialog (shortcut: Ctrl + G) will have decile splitter block start positions cached"
./__open_relation "$relname"