Query help

Hi all,

I've got a query that looks through a table I use for my little
search engine. It's something of a reverse-index but not quite, where a
proper reverse index would have 'word | doc1, doc3, doc4, doc7' showing
all the docs the keyword is in, mine has an entry for eac

I've got a query like:

SELECT
sch_id, sch_for_table, sch_ref_id, sch_instances
FROM
search_index
WHERE
(sch_keyword LIKE '%digi%' OR sch_keyword LIKE '%madi%')
AND
sch_for_table!='client'
AND
... (more restrictions)
ORDER BY
sch_instances DESC;

This returns references to a data column (sch_ref_id) in a given
table (sch_for_table) for each matched keyword.

The problem I am having is that two keywords might reference the same
table/column which would, in turn, give me two+ search results pointing
to the same entry.

What I would like to do is, when two or more results match the same
'sch_ref_id' and 'sch_for_table' to merge the results. Specifically, the
'sch_instances' column is the number of times the given keyword is found
in the table/column. I'd like to add up the number in the duplicate
results (to give it a higher accuracy and move it up the search results).

Is this possible or would I need to add this logic in my program? I'd
rather do it in PostgreSQL though, if I could.

Here is the 'search_index' table I am using:

db=> \d search_index
Table "public.search_index"
Column | Type | Modifiers
---------------+---------+-----------------------------------------------
sch_id | integer | not null default nextval('sch_seq'::regclass)
sch_keyword | text | not null
sch_instances | integer | not null default 1
sch_for_table | text | not null
sch_ref_id | integer | not null
Indexes:
"search_index_pkey" PRIMARY KEY, btree (sch_id)

Thanks in advance to any help you might be able to give me!

Madison