Robert，
I've built an index on this expression firstname || ' ' ||
substring(lastname,1,1). I believe this is the best index for this particular
query. Correct me if I am wrong.
Li
On Aug 3, 2011, at 3:18 AM, Robert Klemme wrote:
> On Tue, Aug 2, 2011 at 11:48 PM, Merlin Moncure wrote:
>> On
On Wed, Aug 3, 2011 at 6:24 PM, Merlin Moncure wrote:
> On Wed, Aug 3, 2011 at 2:18 AM, Robert Klemme
> wrote:
Another observation: That criterion looks suspicious to me. I would
expect any RDBMS to be better able to optimize this:
WHERE firstname = 'Eddie' AND lastname like '
On Wed, Aug 3, 2011 at 3:27 PM, Li Jin wrote:
> Robert，
> I've built an index on this expression firstname || ' ' ||
> substring(lastname,1,1). I believe this is the best index for this
> particular query. Correct me if I am wrong.
Maybe, maybe not. Difficult to tell from a distance. I would ha
On Wed, Aug 3, 2011 at 2:18 AM, Robert Klemme
wrote:
>>> Another observation: That criterion looks suspicious to me. I would
>>> expect any RDBMS to be better able to optimize this:
>>>
>>> WHERE firstname = 'Eddie' AND lastname like 'T%'
>>>
>>> I know it's semantically not the same but I would a
On Wed, Aug 3, 2011 at 3:27 PM, Li Jin wrote:
> Robert，
> I've built an index on this expression firstname || ' ' ||
> substring(lastname,1,1). I believe this is the best index for this
> particular query. Correct me if I am wrong.
Maybe, maybe not. Difficult to tell from a distance. I would ha
On Tue, Aug 2, 2011 at 11:48 PM, Merlin Moncure wrote:
> On Sat, Jul 30, 2011 at 8:10 AM, Robert Klemme
> wrote:
>> On Thu, Jul 28, 2011 at 11:00 PM, Li Jin wrote:
>>> I met with the problem that when I was using WITH clause to reuse a
>>> subquery, I got a huge performance penalty because of qu
On Sat, Jul 30, 2011 at 8:10 AM, Robert Klemme
wrote:
> On Thu, Jul 28, 2011 at 11:00 PM, Li Jin wrote:
>> I met with the problem that when I was using WITH clause to reuse a
>> subquery, I got a huge performance penalty because of query planner.
>> Here are the details, the original query is
>>
On Thu, Jul 28, 2011 at 11:00 PM, Li Jin wrote:
> I met with the problem that when I was using WITH clause to reuse a
> subquery, I got a huge performance penalty because of query planner.
> Here are the details, the original query is
> EXPLAIN ANALYZE WITH latest_identities AS
> (
> SELECT DI
Li Jin writes:
> Anyone knows why the planner is doing this?
WITH is an optimization fence. This is intentional and documented.
regards, tom lane
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Hi guys,
I met with the problem that when I was using WITH clause to reuse a subquery, I
got a huge performance penalty because of query planner.
Here are the details, the original query is
EXPLAIN ANALYZE WITH latest_identities AS
(
SELECT DISTINCT ON (memberid) memberid, username, change
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