CREATE TABLE ovst_temp SELECT * FROM ovst LIMIT 0;
ALTER TABLE ovst_temp MODIFY COLUMN hos_guid VARCHAR(38) NOT NULL UNIQUE PRIMARY KEY;
CREATE UNIQUE INDEX ix_unique ON ovst_temp (vn);
INSERT IGNORE INTO ovst_temp SELECT * FROM ovst;
DROP TABLE ovst;
ALTER TABLE ovst_temp RENAME TO ovst;
CREATE INDEX ix_hn ON ovst (hn);
CREATE INDEX ix_an ON ovst (an);
CREATE INDEX ix_vstdate ON ovst (vstdate);
CREATE INDEX ix_pttype ON ovst (pttype);
CREATE INDEX ix_hn_vstdate ON ovst (hn,vstdate);