Query never returns ...

The following query:

SELECT
    tblSIDEDrugLink.DrugID,
    tblSIDEDrugLink.MedCondID,
    tblMedCond.PatientName AS MedCondPatientName,
    tblMedCond.ProfessionalName AS MedCondProfessionalName,
    tblSIDEDrugLink.Frequency,
    tblSIDEDrugLink.SeverityLevel
FROM
    tblSIDEDrugLink,
    tblMedCond
WHERE
    (tblSIDEDrugLink.DrugID IN ('DG-18698')) AND
    (tblSIDEDrugLink.MedCondID = tblMedCond.MedCondID)
ORDER BY
    tblSIDEDrugLink.DrugID,
    tblSIDEDrugLink.Frequency,
    tblSIDEDrugLink.SeverityLevel,
    tblSIDEDrugLink.MedCondID;

seems to not be liked by PostgreSQL.  Table 'tblSIDEDrugLink' has the
following structure:

CREATE TABLE TBLSIDEDRUGLINK
(
    DRUGID                      VARCHAR(10) NOT NULL,
    MEDCONDID                   VARCHAR(10) NOT NULL,
    FREQUENCY                   INT2,
    SEVERITYLEVEL               INT2,
    CONSTRAINT PK_TBLSIDEDRUGLINK PRIMARY KEY (DRUGID, MEDCONDID)
);

with the following index:
CREATE INDEX IX_TBLSIDEDRUGLINK1 ON TBLSIDEDRUGLINK (MEDCONDID);

This table has 153,288 rows.

Table 'tblMedCond' has the following structure:

CREATE TABLE TBLMEDCOND
(
    MEDCONDID                   VARCHAR(10) NOT NULL,
    PROFESSIONALNAME            VARCHAR(58),
    PATIENTNAME                 VARCHAR(58),
    CONSTRAINT PK_TBLMEDCOND PRIMARY KEY (MEDCONDID)
);

This table has 1,730 rows.

The query above is made by a third-party API that I don't have the
source for, so I can't modify the query in the API, though the
third-party has been quite willing to help out - they may even ship me a
'special' version of the API if there's something in this query that
PostgreSQL for some reason doesn't implement efficiently enough.

If it would help anyone to see the query plan or such - I can modify the
logs to show that, just let me know.

Btw - I've let this query run for a while & I haven't seen it complete
... soooo ... I don't know if it would ever complete or not.

Any help at all is as always, appreciated.

Sincerest regards,
--
Brice Ruth
WebProjkt, Inc.
VP, Director of Internet Technology
http://www.webprojkt.com/