Thread: plugin dev, oid to pointer map

Hi all,

i am about to begin with postgresql plugin development.
Currently i'm trying to become somewhat familiar with the postgresql sources.

Without going too deep into details about the plugin, i want to use
many Oid to pointer relations.
The pointer is a pointer to my own struct (allocated with palloc).
There will be approx. 1000 unique oid/pointer pairs.

Basically, what i want is, to be able to get the pointer to my struct by Oid.

Is there is a suitable hashmap or key-value storage solution in the pg code?
if so, please point me to the right part of the source.

thanks,
Attila Soki

On 29/05/2016 22:10, Attila Soki wrote:
> Hi all,
>

Hello,

> i am about to begin with postgresql plugin development.
>H Currently i'm trying to become somewhat familiar with the postgresql sources.

>
> Without going too deep into details about the plugin, i want to use
> many Oid to pointer relations.
> The pointer is a pointer to my own struct (allocated with palloc).
> There will be approx. 1000 unique oid/pointer pairs.
>
> Basically, what i want is, to be able to get the pointer to my struct by Oid.
>
> Is there is a suitable hashmap or key-value storage solution in the pg code?
> if so, please point me to the right part of the source.
>

Yes, there's an hashtable implementation, see dynahash.c

If you want to use that in shared memory in your extension, you can look
at the pg_stat_statements extension (look for pgss_hash) for an example.

Regards.


--
Julien Rouhaud
http://dalibo.com - http://dalibo.org

> On 30 May 2016, at 02:43, Julien Rouhaud <julien.rouhaud@dalibo.com> wrote:
>
> On 29/05/2016 22:10, Attila Soki wrote:
>> i am about to begin with postgresql plugin development.
>> H Currently i'm trying to become somewhat familiar with the postgresql sources.
>
>>
>> Without going too deep into details about the plugin, i want to use
>> many Oid to pointer relations.
>> The pointer is a pointer to my own struct (allocated with palloc).
>> There will be approx. 1000 unique oid/pointer pairs.
>>
>> Basically, what i want is, to be able to get the pointer to my struct by Oid.
>>
>> Is there is a suitable hashmap or key-value storage solution in the pg code?
>> if so, please point me to the right part of the source.
>>
>
> Yes, there's an hashtable implementation, see dynahash.c
>
> If you want to use that in shared memory in your extension, you can look
> at the pg_stat_statements extension (look for pgss_hash) for an example.


Hello Julien,

exactly what i need

Thank you

Attila Soki