Real config values for bytes needs quotes?

On 27.02.23 09:32, Kyotaro Horiguchi wrote:

I found it frustrating that the line "shared_buffers = 0.1GB" in
postgresql.conf postgresql.conf was causing an error and that the
value required (additional) surrounding single quotes. The attached
patch makes the parser accept the use of non-quoted real values
followed by a unit for such variables. I'm not sure if that syntax
fully covers the input syntax of strtod, but I beieve it is suffucient
for most use cases.

This seems sensible to fix. If you're not sure about the details, write
some test cases. :)

At Thu, 2 Mar 2023 11:54:10 +0100, Peter Eisentraut <peter.eisentraut@enterprisedb.com> wrote in

On 27.02.23 09:32, Kyotaro Horiguchi wrote:

I found it frustrating that the line "shared_buffers = 0.1GB" in
postgresql.conf postgresql.conf was causing an error and that the
value required (additional) surrounding single quotes. The attached
patch makes the parser accept the use of non-quoted real values
followed by a unit for such variables. I'm not sure if that syntax
fully covers the input syntax of strtod, but I beieve it is suffucient
for most use cases.

This seems sensible to fix. If you're not sure about the details,
write some test cases. :)

Thanks. I initially intended to limit the change for REAL to accept
units following a value. However, actually I also modified it to
accept '1e1'.

man strtod says it accepts the following format.

The expected form of the (initial portion of the) string is optional
leading white space as recognized by isspace(3), an optional plus ('+')
or minus sign ('-') and then either (i) a decimal number, or (ii) a
hexadecimal number, or (iii) an infinity, or (iv) a NAN (not-a-number).

A decimal number consists of a nonempty sequence of decimal digits pos‐
sibly containing a radix character (decimal point, locale-dependent,
usually '.'), optionally followed by a decimal exponent. A decimal
exponent consists of an 'E' or 'e', followed by an optional plus or
minus sign, followed by a nonempty sequence of decimal digits, and
indicates multiplication by a power of 10.

It is written in regexp as
'\s*[-+]?(\.\d+|\d+(\.\d*)?)([Ee][-+]?\d+)?'. The leading whitespace
is unnecessary in this specific usage, and we also need to exclude
INTERGER from this set of matches. Therefore, it should be modified to
'[-+]?((\.\d+|\d+\.\d*)([Ee][-+]?\d+)?|\d+([Ee][-+]?\d+))'.

It is translated to the following BNF notation. UNIT_LETTER is also
needed.

{SIGN}?(("."{DIGIT}+|{DIGIT}+"."{DIGIT}*){EXPONENT}?|{DIGIT}+{EXPONENT}){UNIT_LETTER}*

The attached patch applies aforementioned change to guc-file.l and
includes tests for values in certain patters.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center