Re: Indexes not always used after inserts/updates/vacuum analyze

Heh--i was gonna ask why the strange percent representation in the stats 
table.

I just ran a vacuum analyze with the specific column.  Still get the 
same explain plan:

Seq Scan on symbol_data  (cost=0.00..709962.90 rows=369782 width=129)

--Michael

Tom Lane wrote:

>I said:
>
>>>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%. 
>>
>
>Argh, make that 1.8% and 1.7%.
>
>That's still orders of magnitude away from what you say the correct
>frequency is, however: 687 out of 20+ million.  I'd like to think that
>the statistical sampling would be unlikely to make such a large error.
>
>			regards, tom lane
>