Drupal Rebuild node_comment_statistics from http://drupal.org/node/137458#comment-5072066

node_comment_statistics.sql

/**
 * Rebuild the node_comment_statistics
 * turn off when importing
 * $commentvar = variable_get('comment_maintain_node_statistics', TRUE);
 *  variable_set('comment_maintain_node_statistics', FALSE);
 * ref: http://drupal.org/node/137458#comment-5072066
 */


TRUNCATE TABLE node_comment_statistics;
INSERT INTO
    node_comment_statistics
(
    nid,
    last_comment_timestamp,
    last_comment_name,
    last_comment_uid,
    comment_count
)
SELECT
    n.nid,
    IFNULL(last_comment.created,n.changed) AS last_comment_timestamp,
    IFNULL(last_comment.name,null) AS last_comment_name,
    IFNULL(last_comment.uid,n.uid) AS last_comment_uid,
    IFNULL(comment_count.comment_count,0) AS comment_count
FROM
    node AS n
    LEFT OUTER JOIN (SELECT nid, COUNT(*) AS comment_count FROM comment WHERE status=1 GROUP BY nid) AS comment_count ON comment_count.nid=n.nid
    LEFT OUTER JOIN (SELECT nid, MAX(cid) AS max_cid FROM comment WHERE status=1 GROUP by nid) AS max_node_comment ON max_node_comment.nid=n.nid
    LEFT OUTER JOIN (SELECT cid,uid,name,created FROM comment ORDER BY cid DESC LIMIT 1) AS last_comment ON last_comment.cid=max_node_comment.max_cid
WHERE
    n.status=1
ORDER BY
    n.nid;