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Add pg_dissect_walfile_name()

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This function takes in input a WAL segment name and returns a tuple made
of the segment sequence number (dependent on the WAL segment size of the
cluster) and its timeline, as of a thin SQL wrapper around the existing
XLogFromFileName().

This function has multiple usages, like being able to compile a LSN from
a file name and an offset, or finding the timeline of a segment without
having to do to some maths based on the first eight characters of the
segment.

Bump catalog version.

Author: Bharath Rupireddy
Reviewed-by: Nathan Bossart, Kyotaro Horiguchi, Maxim Orlov, Michael
Paquier
Discussion: https://postgr.es/m/CALj2ACWV=FCddsxcGbVOA=cvPyMr75YCFbSQT6g4KDj=gcJK4g@mail.gmail.com
This commit is contained in:
Michael Paquier
2022-12-20 13:36:27 +09:00
parent b3bb7d12af
commit cca1863489
6 changed files with 125 additions and 1 deletions
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53
src/backend/access/transam/xlogfuncs.c
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@@ -432,6 +432,59 @@ pg_walfile_name(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
}
/*
* Extract the sequence number and the timeline ID from given a WAL file
* name.
*/
Datum
pg_dissect_walfile_name(PG_FUNCTION_ARGS)
{
#define PG_DISSECT_WALFILE_NAME_COLS 2
char *fname = text_to_cstring(PG_GETARG_TEXT_PP(0));
char *fname_upper;
char *p;
TimeLineID tli;
XLogSegNo segno;
Datum values[PG_DISSECT_WALFILE_NAME_COLS] = {0};
bool isnull[PG_DISSECT_WALFILE_NAME_COLS] = {0};
TupleDesc tupdesc;
HeapTuple tuple;
char buf[256];
Datum result;
fname_upper = pstrdup(fname);
/* Capitalize WAL file name. */
for (p = fname_upper; *p; p++)
*p = pg_toupper((unsigned char) *p);
if (!IsXLogFileName(fname_upper))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid WAL file name \"%s\"", fname)));
XLogFromFileName(fname_upper, &tli, &segno, wal_segment_size);
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* Convert to numeric. */
snprintf(buf, sizeof buf, UINT64_FORMAT, segno);
values[0] = DirectFunctionCall3(numeric_in,
CStringGetDatum(buf),
ObjectIdGetDatum(0),
Int32GetDatum(-1));
values[1] = Int64GetDatum(tli);
tuple = heap_form_tuple(tupdesc, values, isnull);
result = HeapTupleGetDatum(tuple);
PG_RETURN_DATUM(result);
#undef PG_DISSECT_WALFILE_NAME_COLS
}
/*
* pg_wal_replay_pause - Request to pause recovery
*