SQLite

# queries the in-memory db to produce the space-analysis report.
#
sqlite3 mem :memory:
set tabledef {CREATE TABLE space_used(
   name clob,        -- Name of a table or index in the database file
   tblname clob,     -- Name of associated table
   is_index boolean, -- TRUE if it is an index, false for a table
   is_without_rowid boolean, -- TRUE if WITHOUT ROWID table  
   nentry int,       -- Number of entries in the BTree
   leaf_entries int, -- Number of leaf entries
   depth int,        -- Depth of the b-tree
   payload int,      -- Total amount of data stored in this table or index
   ovfl_payload int, -- Total amount of data stored on overflow pages
   ovfl_cnt int,     -- Number of entries that use overflow
   mx_payload int,   -- Maximum payload size

set isCompressed 0
set compressOverhead 0
set depth 0
set sql { SELECT name, tbl_name FROM sqlite_master WHERE rootpage>0 }
foreach {name tblname} [concat sqlite_master sqlite_master [db eval $sql]] {

  set is_index [expr {$name!=$tblname}]
  set is_without_rowid [is_without_rowid $name]
  db eval {
    SELECT 
      sum(ncell) AS nentry,
      sum((pagetype=='leaf')*ncell) AS leaf_entries,
      sum(payload) AS payload,
      sum((pagetype=='overflow') * payload) AS ovfl_payload,
      sum(path LIKE '%+000000') AS ovfl_cnt,

    set prev $pageno
  }
  mem eval {
    INSERT INTO space_used VALUES(
      $name,
      $tblname,
      $is_index,
      $is_without_rowid,
      $nentry,
      $leaf_entries,
      $depth,
      $payload,     
      $ovfl_payload,
      $ovfl_cnt,   
      $mx_payload,

  # Query the in-memory database for the sum of various statistics 
  # for the subset of tables/indices identified by the WHERE clause in
  # $where. Note that even if the WHERE clause matches no rows, the
  # following query returns exactly one row (because it is an aggregate).
  #
  # The results of the query are stored directly by SQLite into local 
  # variables (i.e. $nentry, $payload etc.).
  #
  mem eval "
    SELECT
      int(sum(
        CASE WHEN (is_without_rowid OR is_index) THEN nentry 
             ELSE leaf_entries 
        END
      )) AS nentry,
      int(sum(payload)) AS payload,
      int(sum(ovfl_payload)) AS ovfl_payload,
      max(mx_payload) AS mx_payload,
      int(sum(ovfl_cnt)) as ovfl_cnt,
      int(sum(leaf_pages)) AS leaf_pages,
      int(sum(int_pages)) AS int_pages,
      int(sum(ovfl_pages)) AS ovfl_pages,

  # ovfl_cnt_percent: Percentage of btree entries that use overflow pages.
  #
  set total_pages [expr {$leaf_pages+$int_pages+$ovfl_pages}]
  set total_pages_percent [percent $total_pages $file_pgcnt]
  set storage [expr {$total_pages*$pageSize}]
  set payload_percent [percent $payload $storage {of storage consumed}]
  set total_unused [expr {$ovfl_unused+$int_unused+$leaf_unused}]
  set avg_payload [divide $payload $nentry]
  set avg_unused [divide $total_unused $nentry]
  if {$int_pages>0} {
    # TODO: Is this formula correct?
    set nTab [mem eval "
      SELECT count(*) FROM (
          SELECT DISTINCT tblname FROM space_used WHERE $where AND is_index=0
      )
    "]
    set avg_fanout [mem eval "
      SELECT (sum(leaf_pages+int_pages)-$nTab)/sum(int_pages) FROM space_used
          WHERE $where
    "]
    set avg_fanout [format %.2f $avg_fanout]
  }
  set ovfl_cnt_percent [percent $ovfl_cnt $nentry {of all entries}]

  # Print out the sub-report statistics.
  #
  statline {Percentage of total database} $total_pages_percent
  statline {Number of entries} $nentry
  statline {Bytes of storage consumed} $storage
  if {$compressed_size!=$storage} {
    set compressed_size [expr {$compressed_size+$compressOverhead*$total_pages}]
    set pct [expr {$compressed_size*100.0/$storage}]
    set pct [format {%5.1f%%} $pct]
    statline {Bytes used after compression} $compressed_size $pct
  }