SELECT current_database(), nspname AS schemaname, c.relname AS tablename, indexname, bs*(sub.relpages)::bigint AS real_size,
 bs*otta::bigint as estimated_size,
 bs*(sub.relpages-otta)::bigint                   AS bloat_size,
 bs*(sub.relpages-otta)::bigint *  100  /  (bs*(sub.relpages)::bigint) AS bloat_ratio
 --  , index_tuple_hdr_bm, maxalign, pagehdr, nulldatawidth, nulldatahdrwidth, datawidth,  sub.reltuples,  sub.relpages --  (DEBUG INFO)
FROM (
 SELECT bs, nspname, table_oid, indexname, relpages, coalesce(
   ceil((reltuples*(4+nulldatahdrwidth))/(bs-pagehdr::float))  +  1,  0  --  ItemIdData size + computed avg size of a tuple (nulldatahdrwidth)
 ) AS otta
 --  , index_tuple_hdr_bm, maxalign, pagehdr, nulldatawidth, nulldatahdrwidth, datawidth, reltuples --  (DEBUG INFO)
FROM (
  SELECT maxalign, bs, nspname, relname AS indexname, reltuples, relpages, relam, table_oid,
 ( index_tuple_hdr_bm +
maxalign - CASE --  Add padding to the index tuple header to align on MAXALIGN
      WHEN index_tuple_hdr_bm%maxalign =  0 THEN maxalign
      ELSE index_tuple_hdr_bm%maxalign
 END
 + nulldatawidth + maxalign - CASE --  Add padding to the data to align on MAXALIGN
WHEN nulldatawidth =  0 THEN 0
      WHEN nulldatawidth::integer%maxalign =  0 THEN maxalign
      ELSE nulldatawidth::integer%maxalign
 END
 )::numeric AS nulldatahdrwidth, pagehdr
 --  , index_tuple_hdr_bm, nulldatawidth, datawidth --  (DEBUG INFO)
FROM (
   SELECT
    i.nspname, i.relname, i.reltuples, i.relpages, i.relam, s.starelid, a.attrelid AS table_oid,
    CASE cluster_version.v >  7
WHEN true THEN current_setting('block_size')::numeric
ELSE 8192::numeric
 END AS bs,
    CASE -- MAXALIGN:  4 on 32bits,  8 on 64bits  (and mingw32 ?)
     WHEN version()  ~  'mingw32' OR version()  ~  '64-bit|x86_64|ppc64|ia64|amd64' THEN 8
ELSE 4
 END AS maxalign,
 /* per page header, fixed size: 20 for 7.X, 24 for others */
    CASE WHEN cluster_version.v >  7
THEN 24
ELSE 20
 END AS pagehdr,
 /* per tuple header: add IndexAttributeBitMapData if some cols are null-able */
    CASE WHEN max(coalesce(s.stanullfrac,0))  =  0
THEN 2  --  IndexTupleData size
     ELSE 2  +  ((  32  +  8  -  1  )  /  8)  --  IndexTupleData size +  IndexAttributeBitMapData size ( max num filed per index +  8  -  1  /8)
 END AS index_tuple_hdr_bm,
 /* data len: we remove null values save space using it fractionnal part from stats */
    sum(  (1-coalesce(s.stanullfrac,  0))  * coalesce(s.stawidth,  1024)  ) AS nulldatawidth
 --  , sum( s.stawidth ) AS datawidth --  (DEBUG INFO)
   FROM pg_attribute AS a
    JOIN pg_statistic AS s ON s.starelid=a.attrelid AND s.staattnum = a.attnum
JOIN (
     SELECT nspname, relname, reltuples, relpages, indrelid, relam,
      string_to_array(pg_catalog.textin(pg_catalog.int2vectorout(indkey)),  ' ')::smallint[] AS attnum
     FROM pg_index
      JOIN pg_class ON pg_class.oid=pg_index.indexrelid
      JOIN pg_namespace ON pg_namespace.oid = pg_class.relnamespace
 ) AS i ON i.indrelid = a.attrelid AND a.attnum = ANY (i.attnum),
 ( SELECT substring(current_setting('server_version') FROM '#"[0-9]+#"%' FOR '#')::integer ) AS cluster_version(v)
   WHERE a.attnum >  0
GROUP BY 1,  2,  3,  4,  5,  6,  7,  8,  9, cluster_version.v
 ) AS s1
 ) AS s2
  JOIN pg_am am ON s2.relam = am.oid WHERE am.amname =  'btree'
)  as sub
JOIN pg_class c ON c.oid=sub.table_oid
WHERE sub.relpages >  2
ORDER BY 2,3,4;