Re: Question about Array data type in PostgreSQL and their link with hash table concept

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Re: Question about Array data type in PostgreSQL and their link with hash table concept

От:
Dariyoosh Dariyoosh <d.sunforums@gmail.com>
Дата:
Hi,

Thanks a lot for your clarification and the link about hstore

Regards,
Dariyoosh


On Tue, May 27, 2014 at 2:44 PM, Luca Vernini <lucazeo@gmail.com> wrote:
2014-05-27 14:39 GMT+02:00 Dariyoosh Dariyoosh <d.sunforums@gmail.com>:

> Are arrays in PostgreSQL like associative arrays in Oracle PL/SQL hash
> tables?, that is an
> association between key & values? where the integer indexes stand in reality
> for keys?

No, arrays in PostgreSQL are just arrays.
You can consider the position like a special case of key.. but it is
not, because it is just a position and cannot be set.
For key value you can consider hstore:
http://www.postgresql.org/docs/9.3/static/hstore.html
Or build your own multi dimension array.

> Thanks in advance,

Regards,

Lucazeo.

Question about Array data type in PostgreSQL and their link with hash table concept

От:
Dariyoosh Dariyoosh <d.sunforums@gmail.com>
Дата:
Hi,

I would like to ask a question about Array type. My question is somewhat a comparison between
Oracle PL/SQL & PostgreSQL.

I was reading the online documentation at the following link about the Array data type and
I read the following note:

http://www.postgresql.org/docs/9.3/interactive/arrays.html
Tip: Arrays are not sets; searching for specific array elements can be a sign of database misdesign.
Consider using a separate table with a row for each item that would be an array element.
This will be easier to search, and is likely to scale better for a large number of elements.

Are arrays in PostgreSQL like associative arrays in Oracle PL/SQL hash tables?, that is an
association between key & values? where the integer indexes stand in reality for keys?

Thanks in advance,

Re: Question about Array data type in PostgreSQL and their link with hash table concept

От:
Luca Vernini <lucazeo@gmail.com>
Дата:
2014-05-27 14:39 GMT+02:00 Dariyoosh Dariyoosh :

> Are arrays in PostgreSQL like associative arrays in Oracle PL/SQL hash
> tables?, that is an
> association between key & values? where the integer indexes stand in reality
> for keys?

No, arrays in PostgreSQL are just arrays.
You can consider the position like a special case of key.. but it is
not, because it is just a position and cannot be set.
For key value you can consider hstore:
http://www.postgresql.org/docs/9.3/static/hstore.html
Or build your own multi dimension array.

> Thanks in advance,

Regards,

Lucazeo.
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