Page search function fails when using Drupal installed with PostgreSQL (with working code provided)

I am using a Drupal installation with PostgreSQL 8.4.4. After setting up the search box (with the Acquia Prosper theme 6.x-1.0-beta4), re-indexing my site, and attempting to search, I get the following error ...

* warning: pg_query(): Query failed: ERROR: operator does not exist: integer || integer LINE 1: ...d), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - 12... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. in /var/www/foo/includes/database.pgsql.inc on line 139.
* user warning: query: SELECT COUNT(*) FROM (SELECT i.type, i.sid, 5 * (4.1443562157055 * SUM(i.score * t.count)) + 5 * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - 1282555024) * 6.43e-8) + 5 * (2.0 - 2.0 / (1.0 + MAX(c.comment_count) * 1)) AS score FROM search_index i INNER JOIN search_total t ON i.word = t.word INNER JOIN node n ON n.nid = i.sid LEFT JOIN node_comment_statistics c ON c.nid = i.sid WHERE n.status = 1 AND (i.word = 'love') AND i.type = 'node' GROUP BY i.type, i.sid HAVING COUNT(*) >= 1) n1 in /var/www/foo/modules/search/search.module on line 958.
* warning: pg_query(): Query failed: ERROR: operator does not exist: integer || integer LINE 1: ...d), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - 12... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. in /var/www/foo/includes/database.pgsql.inc on line 139.
* user warning: query: SELECT i.type, i.sid, 5 * (4.1443562157055 * SUM(i.score * t.count)) + 5 * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - 1282555024) * 6.43e-8) + 5 * (2.0 - 2.0 / (1.0 + MAX(c.comment_count) * 1)) AS score FROM search_index i INNER JOIN search_total t ON i.word = t.word INNER JOIN node n ON n.nid = i.sid LEFT JOIN node_comment_statistics c ON c.nid = i.sid WHERE n.status = 1 AND (i.word = 'love') AND i.type = 'node' GROUP BY i.type, i.sid HAVING COUNT(*) >= 1 ORDER BY score DESC LIMIT 10 OFFSET 0 in /var/www/foo/modules/search/search.module on line 958.

I **think** the problem is that PostgreSQL does not support the operator "||" as a logical operator. Changing it to an "OR" will not work because both sides of the expression need to be a boolean type. A possible solution is to use COALESCE. So changing line 1238 of node.module from ...

$ranking[] = '%d * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - %d) * 6.43e-8)';

... to ...

$ranking[] = '%d * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), COALESCE(MAX(c.last_comment_timestamp),1)) - %d) * 6.43e-8)';

**should** work for both PostgreSQL and MySQL.