[postgres@sofa ~]$ sql_tdwtf posts_per_topic

WITH post_counts AS (
        SELECT COUNT(*) as post_count, topic_id
        FROM posts
        GROUP BY topic_id
)
SELECT post_count, COUNT(*)
FROM post_counts
GROUP BY post_count
ORDER BY post_count ASC


 post_count | count
------------+-------
          1 |  1191
          2 |   502
          3 |   196
          4 |   130
          5 |   116
          6 |   114
          7 |    77
          8 |    79
          9 |    53
         10 |    54
         11 |    48
         12 |    51
         13 |    48
         14 |    38
         15 |    58
         16 |    35
         17 |    34
         18 |    40
         19 |    38
         20 |    32
         21 |    26
         22 |    26
         23 |    22
         24 |    28
         25 |    22
         26 |    22
         27 |    29
         28 |    26
         29 |    18
         30 |    14
         31 |    21
         32 |    14
         33 |    20
         34 |    14
         35 |    11
         36 |    20
         37 |    16
         38 |    19
         39 |    10
         40 |     7
         41 |    12
         42 |    17
         43 |    15
         44 |    13
         45 |     7
         46 |    10
         47 |    14
         48 |     6
         49 |    11
         50 |    13
         51 |     7
         52 |     5
         53 |    14
         54 |     8
         55 |    11
         56 |    10
         57 |     7
         58 |    15
         59 |     5
         60 |     9
         62 |     8
         63 |     9
         64 |     8
         65 |     3
         66 |     6
         67 |     6
         68 |     4
         69 |     5
         70 |     2
         71 |     5
         72 |     5
         73 |     9
         74 |     7
         75 |     5
         76 |     8
         77 |     4
         78 |     3
         79 |     4
         80 |     5
         81 |     4
         82 |     4
         83 |     2
         84 |     3
         85 |     6
         86 |     6
         87 |     3
         88 |     2
         89 |     3
         90 |     1
         92 |     3
         93 |     9
         94 |     2
         95 |     3
         96 |     6
         98 |     2
        100 |     3
        101 |     3
        102 |     6
        103 |     2
        104 |     1
        105 |     1
        106 |     4
        107 |     4
        108 |     3
        110 |     2
        111 |     4
        112 |     3
        113 |     2
        114 |     1
        115 |     1
        116 |     1
        117 |     1
        118 |     5
        119 |     1
        120 |     1
        121 |     2
        122 |     2
        124 |     4
        125 |     2
        126 |     2
        127 |     1
        128 |     2
        129 |     1
        131 |     1
        133 |     1
        134 |     1
        136 |     1
        137 |     2
        139 |     1
        140 |     3
        141 |     2
        142 |     1
        143 |     2
        144 |     2
        145 |     5
        146 |     3
        147 |     1
        148 |     2
        149 |     1
        151 |     1
        153 |     1
        154 |     1
        155 |     2
        156 |     1
        157 |     3
        158 |     3
        159 |     1
        160 |     1
        161 |     3
        162 |     3
        163 |     1
        164 |     1
        165 |     1
        169 |     1
        170 |     1
        171 |     3
        172 |     2
        173 |     1
        174 |     1
        176 |     1
        181 |     1
        182 |     2
        185 |     1
        186 |     1
        189 |     1
        190 |     2
        191 |     1
        192 |     1
        194 |     1
        198 |     4
        200 |     1
        202 |     1
        204 |     1
        205 |     3
        206 |     1
        207 |     1
        210 |     1
        216 |     2
        223 |     1
        225 |     1
        232 |     1
        234 |     2
        253 |     1
        264 |     2
        269 |     1
        272 |     1
        277 |     1
        284 |     1
        287 |     1
        290 |     1
        297 |     1
        298 |     1
        304 |     1
        309 |     1
        316 |     2
        321 |     1
        326 |     1
        329 |     1
        333 |     1
        337 |     1
        340 |     1
        341 |     1
        342 |     1
        344 |     1
        383 |     1
        395 |     1
        407 |     1
        423 |     1
        442 |     1
        444 |     1
        461 |     1
        470 |     1
        509 |     1
        558 |     1
        583 |     1
        603 |     1
        619 |     1
        623 |     1
        648 |     1
        651 |     1
        714 |     1
        729 |     1
        756 |     1
        761 |     1
        957 |     1
       2977 |     1
       3502 |     1
       4015 |     1
       4760 |     1
      28423 |     1
(230 rows)