The table breakdown consists of about 8000 symbol_names with at most 5000 rows of data for each symbol ( stock market history ).
So, those sample percents seem huge. The most any symbol would have would be about 5000 / (8000*5000) = .0125%
--Michael
Tom Lane wrote:
[EMAIL PROTECTED]">"Michael G. Martin" <[EMAIL PROTECTED]> writes:Here is what is actually there:select count(*) from symbol_data where symbol_name='ELTE';
687
Hmm. Do you have reason to think that that was also true when you last
did VACUUM ANALYZE or VACUUM?Here is the pg_stat query:
select * from pg_stats where tablename = 'symbol_data' and attname
='symbol_name';
tablename | attname | null_frac | avg_width | n_distinct
| most_common_vals
|
most_common_freqs
| histogram_bounds | correlation
-------------+-------------+-----------+-----------+------------+----------------------------------------------+---------------------------------------------------------------------------------------------------------------+-----------------------------------------------------+-------------
symbol_data | symbol_name | 0 | 7 | 152988 |
{EBALX,ELTE,LIT,OEX,RESC,BS,ESH,HOC,IBC,IDA} |
{0.0183333,0.0173333,0.00166667,0.00166667,0.00166667,0.00133333,0.00133333,0.00133333,0.00133333,0.00133333}
| {A,BMO ,DBD,FSCHX,IIX,MAS,NSANY,PTEC,SR,UTIL,_^^VPM} | 0.128921
(1 row)
What this says is that in the last ANALYZE, EBALX accounted for 18% of
the sample, and ELTE for 17%. Does that seem plausible to you? If the
sample was accurate then I'd agree with the planner's choices. It'd
seem that either your table contents are changing drastically (in which
case more-frequent ANALYZEs may be the answer), or you had the bad luck
to get a very unrepresentative sample, or there's some bug in the
statistical calculations.
regards, tom lane
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