Re: SQL-spec incompatibilities in similar_escape() and related stuff

>>>>> "Andrew" == Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:

Andrew> The ESCAPE part could in theory be ambiguous if the SIMILAR
Andrew> expression ends in a ... SIMILAR TO xxx operator, since then we
Andrew> wouldn't know whether to attach the ESCAPE to that or keep it
Andrew> as part of the function syntax. But I think this is probably a
Andrew> non-issue. More significant is that ... COLNAME ! ESCAPE ...
Andrew> again has postfix- vs. infix-operator ambiguities.

And this ambiguity shows up already in other contexts:

select 'foo' similar to 'f' || escape escape escape from (values ('oo')) v(escape);
psql: ERROR: syntax error at or near "escape"
LINE 1: select 'foo' similar to 'f' || escape escape escape from (va...

select 'foo' similar to 'f' || escape escape from (values ('oo')) v(escape);
psql: ERROR: operator does not exist: unknown ||
LINE 1: select 'foo' similar to 'f' || escape escape from (values ('...

I guess this happens because ESCAPE has precedence below POSTFIXOP, so
the ('f' ||) gets reduced in preference to shifting in the first ESCAPE
token.

--
Andrew (irc:RhodiumToad)