This sounds like a very useful change. As you say in the RFC, these
operators are going to be more and more common for Postgres users now that
they've been defined for JSON types, and users of most other DBMSes will be
Thanks, the patch is been sitting on my HD since a few years now. Mostly
no one complained about the geometric operators containing a "?", but
for JSON I guess it's already a bit too late.
I wonder if there's any way we can gauge the BC impact, specifically this
The only exception to that is that Postgres (and possibly other RDMSs)
allows the creation of custom operators: anyone having a custom “??”
operator in use would need to escape it as “????”.
- Are there any standard or public Postgres extensions that define a "??"
operator? e.g. anything published on https://pgxn.org/
I couldn't find anything, but I can try and ask on the postgres mailing
- Are there any other databases supported by PDO that allow custom
operators, or which might have a "??" operator or syntax token?
Not that I know of. Researching that hasn't been easy, but it seems that
most of the databases use "?" for positional parameters in prepared
queries. Any additional help would be appreciated.
If there is a risk of this affecting a reasonable number of people, we
could add a deprecation notice on encountering "??" in any SQL string in
7.4, and postpone adding the escaping mechanism until 8.0.
Nice catch. I thought one couldn't have "??" but it seems the parser
currently doesn't allow two consecutive positional parameter question
marks and "??" was sent as-is. I'll try doing more research on the topic.
One other thing worth clarifying is the precise circumstances where ?? will
be treated as an escape. Is it only when it's a separate "word" (start/end
of string or surrounded by whitespace)? For instance, would "A ??= B" be
"unescaped" to "A ?= B" or passed through as is? Note that this changes the
scope of the BC break, as well as the usability of the chosen syntax, as
both "?=" and "??=" could be defined as operators.
No word boundaries involved. Any occurrence of "??" outside comments
will be translated into "?", so that operators containing the "?" ("A ?|
B", "A ?& B") can be used. If one had defined both "?=" and "??=", they
would need to be escaped in PDO as "??=" and "????=".
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