nonremovable row ?

Hi,

I have a strange problem ...
Look at what I have done ...

# select count(*) from domains_ranks;
count
--------
26927405
(1 row)

# DELETE from domains_ranks where date_rank < now() - '3 days'::interval;
DELETE 26232918

# select count(*) from domains_ranks;
count
--------
694487
(1 row)

# VACUUM full verbose analyze domains_ranks;
INFO: vacuuming "public.domains_ranks"
INFO: "domains_ranks": found 0 removable, 26927405 nonremovable row versions
in 185707 pages
DETAIL: 26232918 dead row versions cannot be removed yet.
Nonremovable row versions range from 52 to 52 bytes long.
There were 0 unused item pointers.
Total free space (including removable row versions) is 9662924 bytes.
0 pages are or will become empty, including 0 at the end of the table.
185707 pages containing 9662924 free bytes are potential move destinations.
CPU 6.31s/95.83u sec elapsed 193.35 sec.
INFO: index "domains_ranks_pkey" now contains 26927405 row versions in 80122
pages
DETAIL: 0 index pages have been deleted, 0 are currently reusable.
CPU 2.34s/0.99u sec elapsed 109.04 sec.
INFO: index "ix_domains_ranks_id_site_rank" now contains 26927405 row
versions in 122449 pages
DETAIL: 0 index pages have been deleted, 0 are currently reusable.
CPU 4.87s/1.63u sec elapsed 1207.43 sec.
INFO: "domains_ranks": moved 0 row versions, truncated 185707 to 185707 pages
DETAIL: CPU 0.00s/0.00u sec elapsed 0.04 sec.
INFO: analyzing "public.domains_ranks"
INFO: "domains_ranks": scanned 185707 of 185707 pages, containing 694487 live
rows and 26232918 dead rows; 300000 rows in sample, 694487 estimated total
rows
VACUUM

Why I get 26927405 nonremovable row versions in 185707 pages ?
How to remove them ? I need to free the space quickly !

Thanks for help ...
--
Hervé Piedvache

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