Thread

Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer

Bruce Momjian <maillist@candle.pha.pa.us> — 1999-03-18T18:56:30Z

> Agreed, this is ok as long as
> 
> vac=> create table table1 (field1 int);
> CREATE
> vac=> insert into table1 values (1);
> INSERT 1583349 1
> vac=> create index i_table1__field1 on table1 (field1);
> CREATE
> vac=> explain select * from table1 where field1 = 1;
> NOTICE:  QUERY PLAN:
> 
> Seq Scan on table1  (cost=1.03 size=1 width=4)
> 
> - SeqScan is used for small tables.
> 
> So, only bug reported is left.

My guess is that the creation of the index updates the table size
statistics.

However, when I see zero size, I don't know if it is accurate, or if
someone has added rows since the last vacuum/index creation, so I think
it is correct to use an index on a zero-length table if it is
appropriate.  If the size is 1, I will assume that number is accurate,
and do a sequential scan.

Does that make sense?


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