Re: Searching GIN-index (FTS) and sort by timestamp-column

> On 16 Mar 2016, at 16:37, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Andreas Joseph Krogh <andreas(at)visena(dot)com> writes:
>> 1. Why isnt' folder_id part of the index-cond?
>
> Because a GIN index is useless for sorting.

I don't see how gin inability to return sorted data relates to index condition.
In fact i tried to reproduce the example,
and if i change folder_id to int from bigint, then index condition with folder_id is used

Index Cond: ((fts_all @@ '''hi'''::tsquery) AND (folder_id = 1))

>
>> 2. Is there a way to make it use the (same) index to sort by
>> received_timestamp?
>
> No.
>
>> 3. Using a GIN-index, is there a way to use the index at all for sorting?
>
> No.
>
>> 4. It doesn't seem like ts_rank uses the index for sorting either.
>
> Same reason.
>
> regards, tom lane
>
>
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