From: | Greg Stark <gsstark(at)mit(dot)edu> |
---|---|
To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
Cc: | Peter Geoghegan <peter(dot)geoghegan86(at)gmail(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Correctly producing array literals for prepared statements |
Date: | 2011-02-23 15:25:00 |
Message-ID: | AANLkTikawz+RNw3G9Dy1in_YE+udwinDU6JX0z-y01xt@mail.gmail.com |
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Lists: | pgsql-hackers |
On Wed, Feb 23, 2011 at 3:16 PM, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
> On 02/23/2011 10:09 AM, Peter Geoghegan wrote:
>>
>> On 23 February 2011 04:36, Greg Stark<gsstark(at)mit(dot)edu> wrote:
>>>
>>> This is only true for server encodings. In a client library I think
>>> you lose on this and do have to deal with it. I'm not sure what client
>>> encodings we do support that aren't ascii-supersets though, it's
>>> possible none of them generate quote characters this way.
>>
>> I'm pretty sure all of the client encodings Tatsuo mentions are ASCII
>> supersets. The absence of by far the most popular non-ASCII superset
>> encoding, UTF-16, as a client encoding indicated that to me. It isn't
>> byte oriented, and Postgres is.
>
>
> They are not. It's precisely because they are not that they are not allowed
> as server encodings.
>
Well just as an example, BIG5 is a 16-bit encoding where the first
byte always has the high bit set. The second byte can't be a ' or "
because those aren't in the allowable range for the second byte. So it
might be safe anyways. However \ is in the allowable range so I'm not
sure.
In the case of BIG5 ascii characters are included inline so any byte
with the high bit *not* set that isn't the second byte of a two-byte
sequence is assumed to be ascii. So an ascii parser would work fine
modulo the problem above with backslashes.
But this is just a special case. Wikipedia implies it's also true for
shift-JIS but there's no guarantee it would work for other client
encodings.
--
greg
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