BUG #7853: Incorrect statistics in table with many dead rows.

The following bug has been logged on the website:

Bug reference: 7853
Logged by: James Skaggs
Email address: jimbob(at)seagate(dot)com
PostgreSQL version: 8.4.14
Operating system: RHEL6
Description:

After "analyze verbose", the table shows 158 million rows. A select count(1)
yields 13.8 million rows.

INFO: analyzing "public.stream_file"
INFO: "stream_file": scanned 30000 of 2123642 pages, containing 184517 live
rows and 2115512 dead rows; 30000 rows in sample, 158702435 estimated total
rows

Here are the table statistics.

Sequential Scans 81853
Sequential Tuples Read 578848425234
Index Scans 1976513672
Index Tuples Fetched 2183339860
Tuples Inserted 65122575
Tuples Updated 308883671
Tuples Deleted 51238760
Tuples HOT Updated 2242897
Live Tuples 163981972
Dead Tuples 7056493
Heap Blocks Read 43483331819
Heap Blocks Hit 43121456487
Index Blocks Read 134539277
Index Blocks Hit 13606451182
Toast Blocks Read
Toast Blocks Hit
Toast Index Blocks Read
Toast Index Blocks Hit
Last Vacuum 2013-02-04 10:06:44.058743-07
Last Autovacuum 2013-02-04 16:11:34.289823-07
Last Analyze 2013-02-04 14:22:27.848547-07
Last Autoanalyze 2013-02-01 17:37:29.855553-07
Table Size 17 GB
Toast Table Size none
Indexes Size 34 GB
Query returned successfully with no result in 4094 ms.

Bad statistics led to a bad plan. We will cluster the table today to see if
that fixes it, but I think statistics should be correct, regardless of the
state of a table. BTW, Coverity product requries 8.x, and we'll upgrade to
8.4.15 today. Didn't see anything about better statistics in the 8.4.15
changelog.