Stefan Kaltenbrunner wrote:
> Jan Wieck wrote:
>   
>> On 7/11/2006 12:43 PM, Christopher Browne wrote:
>>
>>     
>>> I have set up tarballs for a first release candidate; Jan should be
>>> uploading those soon, and I'll see about updating the web site when they
>>> are uploaded...
>>>       
>> I have run them through a compile and a few tests and uploaded them to 
>> the usual location at
>>
>> http://developer.postgresql.org/~wieck/slony1/download/
>>
>> One thing I wanted to discuss is related to a recent discussion on the 
>> hackers mailing list with respect to possible btree corruption due to 
>> xxid not being suitable. With a single origin setup, there is not 
>> problem during normal operation. But even then, any failover of move set 
>> could immediately cause the btree on the xid only (not the one on 
>> node-id, xid) to corrupt. I remember that this index was added because 
>> of the backend failure to use the one with the node-id. But that IMO 
>> doesn't warrant the risk of corrupting the index at the very time there 
>> is already trouble in the house (move set or failover isn't done because 
>> it is such a boring day).
>>     
>
> there is another issue with the current code - while it compiles and
> works fine against postgresql -HEAD with standards_conforming_strings =
> off(the default) it will silently corrupt data with
> standards_conforming_strings = on.
> The reason for this is the rather ad-hoc quoting in slon_quote_literal()
> - it will for example double-escape '\\' in strings leading to
> regression failures with for example testddl.
> Maybe we should take a look at the new escaping functions in the recent
> postgresql releases to make that more safe and future proof ?
>   
Looking at src/include/c.h, it looks as though escape_backslash may be a
backend control for this...

/*
 * Support macros for escaping strings.  escape_backslash should be TRUE
 * if generating a non-standard-conforming string.  Prefixing a string
 * with ESCAPE_STRING_SYNTAX guarantees it is non-standard-conforming.
 * Beware of multiple evaluation of the "ch" argument!
 */
#define SQL_STR_DOUBLE(ch, escape_backslash)^I\
^I((ch) == '\'' || ((ch) == '\\' && (escape_backslash)))

#define ESCAPE_STRING_SYNTAX^I'E'

Is it possible that the resolution is to wrap Slony-I "quoted stuff
submission" code with:

int OldEsc;
OldEsc = escape_backslash;
escape_backslash = TRUE;
[do bunch of stuff]
escape_backslash = OldEsc;
????

That is the same sort of logic now used with DateStyle (where we keep
the old value, and while writing dates, set it to the ISO conformant
form...).