Hi, Dominique,
Thanks for reporting the problem. I will try to find time to look
into it this weekend..
Can't wait to see your patch.
John
On 1/12/12 2:17 PM, Dominique Prunier wrote:
> Hi John,
>
> Thanks for the hint. However, it seems that adding
> query.setSelectClause("p_devtype, count(*)") breaks something, not sure what
> exactly:
>
> Error -- bundles::ctor "__1" is not the name of a column in table
> data_property_flat
> Error -- bundles::ctor received an exception, start cleaning up
> terminate called after throwing an instance of 'ibis::bad_alloc'
> what(): unknown column name
>
> For the patch, it allows to jump from bundle to bundle instead of line by
> line when iterating over a result set (which artificially repeat same bundle
> to simulate a real query SQL result). Feel free to include it/modify it/drop
> it. Soon enough, i should also submit a patch that allows me to access long
> values from a result set in the C api.
>
> Thanks,
>
> -----Original Message-----
> From: K. John Wu [mailto:[email protected]]
> Sent: Thursday, January 12, 2012 4:41 PM
> To: FastBit Users
> Cc: Dominique Prunier
> Subject: Re: [FastBit-users] Recommanded way to do SELECT DISTINCT
> <string_col> programatically
>
> Hi, Dominique,
>
> A quick want to get what you want might be to change the select clause
> to something like
>
> query.setSelectClause("p_devtype, count(*)");
>
> The bundle will have the unique values for p_devtype and it does not
> cost extra to compute the counts.
>
> Internally, FastBit is dealing with integer version of the strings.
> You will still have to use getString to retrieve the actual string values.
>
> By the way, would you mind give a quick explanation about what is in
> the patch you've sent out? Do you intend it to be included in FastBit
> release? I would like to have a brief description of the patch to put
> in the ChangeLog if you intend to make it available to others.
>
> Thanks.
>
> John
>
>
>
> On 1/12/12 1:07 PM, Dominique Prunier wrote:
>> In the meantime, i did a very simple modification to be able to do
>> what i wanted from the C api (see attached)
>>
>>
>>
>> Thanks,
>>
>>
>>
>> *From:*[email protected]
>> [mailto:[email protected]] *On Behalf Of *Dominique
>> Prunier
>> *Sent:* Thursday, January 12, 2012 3:04 PM
>> *To:* FastBit Users
>> *Subject:* [FastBit-users] Recommanded way to do SELECT DISTINCT
>> <string_col> programatically
>>
>>
>>
>> Hi,
>>
>>
>>
>> I’m trying to reproduce a SELECT DISTINCT from a previous SQL system
>> migrated to FastBit and so far, i ended up with the following snippet
>> of code:
>>
>>
>>
>> ibis::part part("<part>", static_cast<const char*>(0));
>>
>> ibis::query query;
>>
>> query.setPartition(&part);
>>
>> query.setWhereClause(static_cast<const char*>(0));
>>
>> query.setSelectClause("p_devtype");
>>
>> query.evaluate();
>>
>> std::auto_ptr<ibis::bundle> bdl(ibis::bundle::create(query));
>>
>> for (int ri = 0; ri < bdl->size(); ri++) {
>>
>> std::cout << bdl->getString(ri, 0) << "\n";
>>
>> }
>>
>>
>>
>> My questions are:
>>
>> · Is it the recommended way of doing it ? Is there any other
>> ways ? Is this something i can do trhough the C api ?
>>
>> · The getString(ri, 0) decorates strings with a leading and
>> trailing quotes, is there another method to get the undecorated string ?
>>
>>
>>
>> Thanks,
>>
>>
>>
>> */Dominique Prunier/**//*
>>
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>>
>>
>>
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