Re: grep -f keyword data query

Hello David

Thank your for your comment.

2015年12月30日(水) 10:15 David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>:

> On 30 December 2015 at 13:56, Hiroyuki Sato <hiroysato(at)gmail(dot)com> wrote:
>
>> 2015年12月30日(水) 6:04 David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>:
>>
>>> On 30 December 2015 at 04:21, Hiroyuki Sato <hiroysato(at)gmail(dot)com> wrote:
>>>
>>>> 2015年12月29日(火) 4:35 Jeff Janes <jeff(dot)janes(at)gmail(dot)com>:
>>>>
>>>>>
>>>>>
>>>> But, the planner refuses to use this index for your query anyway,
>>>>> because it can't see that the patterns are all left-anchored.
>>>>>
>>>>> Really, your best bet is refactor your url data so it is stored with a
>>>>> url_prefix and url_suffix column. Then you can do exact matching
>>>>> rather than pattern matching.
>>>>>
>>>> I see, exact matching faster than pattern matting.
>>>> But I need pattern match in path part
>>>> (ie, http://www.yahoo.com/a/b/c/... )
>>>> I would like to pattern match '/a/b/c' part.
>>>>
>>>
>>> If your pattern matching is as simple as that, then why not split the
>>> /a/b/c/ part out as mentioned by Jeff? Alternatively you could just write a
>>> function which splits that out for you and returns it, then index that
>>> function, and then just include a call to that function in the join
>>> condition matching with the equality operator. That'll allow hash and merge
>>> joins to be possible again.
>>>
>>
>> Could you tell me more detail about Alternatively part?
>>
>> It is good idea to split host and part.
>> I'll try it.
>>
>> My matching pattern is the following
>> 1, http://www.yahoo.com/a/b/% (host equal, path like)
>> 2, http://%.yahoo.com/a/b/% (host and path like )
>>
>
> It seems I misunderstood your pattern matching. The example you supplied
> earlier indicated you just needed to match the document part (/a/b/c/) and
> just ignore the protocol://host part, in which case you could have written
> a function which took a text parameter, say: "http://www.yahoo.com/a/b/c/",
> and returned "/a/b/c", then performed: create index on yourtable
> (thatfunction(yourcolumn)); However that method won't help you, as it seems
> your pattern matching is more complex than the previous example that you
> supplied.
>
> --
> David Rowley http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services
>