The only guess I have is that perhaps the size of the subquery is considered a CLOB? I have no null values for the fields selected AFAIK. SELECT DISTINCT kbq_ent.qid AS kbq_ent_qid, kbq_ent.category AS kbq_ent_category, kbq_ent.consequence AS kbq_ent_consequence, kbq_ent.diagnosis AS kbq_ent_diagnosis, kbq_ent.last_service_modify_datetime AS kbq_ent_last_servic_1, kbq_ent.patchable AS kbq_ent_patchable, kbq_ent.pci_flag AS kbq_ent_pci_flag, kbq_ent.published_datetime AS kbq_ent_published_d_2, kbq_ent.severity_level AS kbq_ent_severity_le_3, kbq_ent.solution AS kbq_ent_solution, kbq_ent.title AS kbq_ent_title, kbq_ent.vuln_type AS kbq_ent_vuln_type, kbq_ent.discovery_remote AS kbq_ent_discovery_r_4, kbq_ent.cvss_base AS kbq_ent_cvss_base, kbq_ent.cvss_temporal AS kbq_ent_cvss_tempor_5, kbq_ent.last_customization_user_login AS kbq_ent_last_custom_6,kbq_ent.last_customization_datetime AS kbq_ent_last_custom_7 FROM kbq_ent JOIN (SELECT vuln_eid AS vuln_eid, qid AS qid, anon_2.rel_eid AS anon_2_rel_eid FROM ( SELECT entity_vuln.entity_id AS vuln_eid, entity_vuln.qid AS qid FROM entity_vuln ) JOIN ( SELECT entity_responsible_org.entity_id AS rel_eid FROM entity_responsible_org WHERE entity_responsible_org.org_id = :org_id_1 ) anon_2 ON vuln_eid = anon_2.rel_eid) anon_1 ON kbq_ent.qid = anon_1.qid `kbq_ent.solution AS kbq_ent_solution` is a CLOB.