Re: BUG #17245: Index corruption involving deduplicated entries

This doesn't look too healthy:

CREATE TABLE page (
  page_id SERIAL NOT NULL,
  page_namespace INT NOT NULL,
  page_title TEXT NOT NULL,
  page_restrictions TEXT DEFAULT NULL,
  page_is_redirect SMALLINT DEFAULT 0 NOT NULL,
  page_is_new SMALLINT DEFAULT 0 NOT NULL,
  page_random FLOAT NOT NULL,
  page_touched TIMESTAMPTZ NOT NULL,
  page_links_updated TIMESTAMPTZ DEFAULT NULL,
  page_latest INT NOT NULL,
  page_len INT NOT NULL,
  page_content_model TEXT DEFAULT NULL,
  page_lang TEXT DEFAULT NULL,
  PRIMARY KEY(page_id)
);

INSERT INTO page (page_namespace, page_title, page_is_redirect,
page_is_new, page_random, page_touched, page_latest, page_len) select
case when random() > 0.5 then 1 else 0 end, random()::text, 0, 0,
42.0, now(), 0, 42 from generate_series(1, 170000);

CREATE INDEX page_main_title ON page USING btree(page_title text_pattern_ops)
WHERE (page_namespace = 0);

postgres=# select count(*) from page;
 count
--------
 170000
(1 row)

postgres=# select count(*) from page where page_namespace = 0;
 count
-------
 84934
(1 row)

postgres=# explain select count(*) from page where page_namespace = 0;
                                          QUERY PLAN
----------------------------------------------------------------------------------------------
 Aggregate  (cost=3179.75..3179.76 rows=1 width=8)
   ->  Index Only Scan using page_main_title on page
(cost=0.42..2967.85 rows=84762 width=0)
(2 rows)