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Add pg_size_bytes() to parse human-readable size strings.

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This will parse strings in the format produced by pg_size_pretty() and
return sizes in bytes. This allows queries to be written with clauses
like "pg_total_relation_size(oid) > pg_size_bytes('10 GB')".

Author: Pavel Stehule with various improvements by Vitaly Burovoy
Discussion: http://www.postgresql.org/message-id/CAFj8pRD-tGoDKnxdYgECzA4On01_uRqPrwF-8LdkSE-6bDHp0w@mail.gmail.com
Reviewed-by: Vitaly Burovoy, Oleksandr Shulgin, Kyotaro Horiguchi,
    Michael Paquier and Robert Haas
This commit is contained in:
Dean Rasheed
2016-02-20 09:57:27 +00:00
parent 091b6055e3
commit 53874c5228
7 changed files with 331 additions and 3 deletions
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149
src/backend/utils/adt/dbsize.c
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@ -699,6 +699,155 @@ pg_size_pretty_numeric(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(result));
}
/*
* Convert a human-readable size to a size in bytes
*/
Datum
pg_size_bytes(PG_FUNCTION_ARGS)
{
text *arg = PG_GETARG_TEXT_PP(0);
char *str,
*strptr,
*endptr;
char saved_char;
Numeric num;
int64 result;
bool have_digits = false;
str = text_to_cstring(arg);
/* Skip leading whitespace */
strptr = str;
while (isspace((unsigned char) *strptr))
strptr++;
/* Check that we have a valid number and determine where it ends */
endptr = strptr;
/* Part (1): sign */
if (*endptr == '-' || *endptr == '+')
endptr++;
/* Part (2): main digit string */
if (isdigit((unsigned char) *endptr))
{
have_digits = true;
do
endptr++;
while (isdigit((unsigned char) *endptr));
}
/* Part (3): optional decimal point and fractional digits */
if (*endptr == '.')
{
endptr++;
if (isdigit((unsigned char) *endptr))
{
have_digits = true;
do
endptr++;
while (isdigit((unsigned char) *endptr));
}
}
/* Complain if we don't have a valid number at this point */
if (!have_digits)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid size: \"%s\"", str)));
/* Part (4): optional exponent */
if (*endptr == 'e' || *endptr == 'E')
{
long exponent;
char *cp;
/*
* Note we might one day support EB units, so if what follows isn't a
* number, just treat it all as a unit to be parsed.
*/
exponent = strtol(endptr + 1, &cp, 10);
if (cp > endptr + 1)
{
if (exponent > NUMERIC_MAX_PRECISION ||
exponent < -NUMERIC_MAX_PRECISION)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid size: \"%s\"", str)));
endptr = cp;
}
}
/*
* Parse the number, saving the next character, which may be the first
* character of the unit string.
*/
saved_char = *endptr;
*endptr = '\0';
num = DatumGetNumeric(DirectFunctionCall3(numeric_in,
CStringGetDatum(strptr),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1)));
*endptr = saved_char;
/* Skip whitespace between number and unit */
strptr = endptr;
while (isspace((unsigned char) *strptr))
strptr++;
/* Handle possible unit */
if (*strptr != '\0')
{
int64 multiplier = 0;
/* Trim any trailing whitespace */
endptr = str + VARSIZE_ANY_EXHDR(arg) - 1;
while (isspace((unsigned char) *endptr))
endptr--;
endptr++;
*endptr = '\0';
/* Parse the unit case-insensitively */
if (pg_strcasecmp(strptr, "bytes") == 0)
multiplier = 1;
else if (pg_strcasecmp(strptr, "kb") == 0)
multiplier = 1024;
else if (pg_strcasecmp(strptr, "mb") == 0)
multiplier = 1024 * 1024;
else if (pg_strcasecmp(strptr, "gb") == 0)
multiplier = 1024 * 1024 * 1024;
else if (pg_strcasecmp(strptr, "tb") == 0)
multiplier = 1024 * 1024 * 1024 * 1024L;
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid size: \"%s\"", text_to_cstring(arg)),
errdetail("Invalid size unit: \"%s\".", strptr),
errhint("Valid units are \"bytes\", \"kB\", \"MB\", \"GB\", and \"TB\".")));
if (multiplier > 1)
{
Numeric mul_num;
mul_num = DatumGetNumeric(DirectFunctionCall1(int8_numeric,
Int64GetDatum(multiplier)));
num = DatumGetNumeric(DirectFunctionCall2(numeric_mul,
NumericGetDatum(mul_num),
NumericGetDatum(num)));
}
}
result = DatumGetInt64(DirectFunctionCall1(numeric_int8,
NumericGetDatum(num)));
PG_RETURN_INT64(result);
}
/*
* Get the filenode of a relation
*