On Sun, Oct 11, 2009 at 10:01:52PM -0500, Peter Hunsberger wrote:
This is interesting, I just ran a similar issue the other day.
Clearly there is a wide range of read / write scenarios that Postgres
should be able to cover. These days, I have a lot of designs leaning
more toward the data
I understood , thanks.
--- 09年10月12日，周一, Martijn van Oosterhout klep...@svana.org 写道：
发件人: Martijn van Oosterhout klep...@svana.org
主题: Re: [GENERAL] table full scan or index full scan?
收件人: Peter Hunsberger peter.hunsber...@gmail.com
抄送: Scott Marlowe scott.marl...@gmail.com, ??
peixu
I have a 30,000,000 records table, counts the record number to need for 40
seconds.
The table has a primary key on column id;
perf=# explain select count(*) from test;
...
-
Aggregate (cost=603702.80..603702.81 rows=1 width=0)
- Seq scan on test
On Mon, 12 Oct 2009, ?? ? wrote:
perf=# select count(*) from test;
In PostgreSQL, if you're selecting every record from the table for a count
of them, you have to visit them all no matter what. The most efficient
way to do that is with a full table scan. Using an index instead requires
Real quick, plain text is preferred on these lists over html. I don't
care myself so much.
On Sun, Oct 11, 2009 at 7:17 PM, 旭斌 裴 peixu...@yahoo.com.cn wrote:
I have a 30,000,000 records table, counts the record number to need for 40
seconds.
The table has a primary key on column id;
2009/10/11 Scott Marlowe scott.marl...@gmail.com:
The postgresql database uses the table full scan.but in oracle, the similar
SQL uses the index full scanning,speed quickly many than postgresql.
Yep, PostgreSQL isn't Oracle. It's a trade off. In pgsql indexes
don't contain visibility info,
