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Add some UUID support functions

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Add uuid_extract_timestamp() and uuid_extract_version().

Author: Andrey Borodin
Reviewed-by: Sergey Prokhorenko, Kirk Wolak, Przemysław Sztoch
Reviewed-by: Nikolay Samokhvalov, Jelte Fennema-Nio, Aleksander Alekseev
Reviewed-by: Peter Eisentraut, Chris Travers, Lukas Fittl
Discussion: https://postgr.es/m/CAAhFRxitJv%3DyoGnXUgeLB_O%2BM7J2BJAmb5jqAT9gZ3bij3uLDA%40mail.gmail.com
This commit is contained in:
Peter Eisentraut
2024-03-19 09:30:24 +01:00
parent d56cb42b54
commit 794f10f6b9
7 changed files with 157 additions and 1 deletions
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64
src/backend/utils/adt/uuid.c
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@@ -20,6 +20,7 @@
#include "utils/fmgrprotos.h"
#include "utils/guc.h"
#include "utils/sortsupport.h"
#include "utils/timestamp.h"
#include "utils/uuid.h"
/* sortsupport for uuid */
@@ -425,3 +426,66 @@ gen_random_uuid(PG_FUNCTION_ARGS)
PG_RETURN_UUID_P(uuid);
}
#define UUIDV1_EPOCH_JDATE 2299161 /* == date2j(1582,10,15) */
/*
* Extract timestamp from UUID.
*
* Returns null if not RFC 4122 variant or not a version that has a timestamp.
*/
Datum
uuid_extract_timestamp(PG_FUNCTION_ARGS)
{
pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
int version;
uint64 tms;
TimestampTz ts;
/* check if RFC 4122 variant */
if ((uuid->data[8] & 0xc0) != 0x80)
PG_RETURN_NULL();
version = uuid->data[6] >> 4;
if (version == 1)
{
tms = ((uint64) uuid->data[0] << 24)
+ ((uint64) uuid->data[1] << 16)
+ ((uint64) uuid->data[2] << 8)
+ ((uint64) uuid->data[3])
+ ((uint64) uuid->data[4] << 40)
+ ((uint64) uuid->data[5] << 32)
+ (((uint64) uuid->data[6] & 0xf) << 56)
+ ((uint64) uuid->data[7] << 48);
/* convert 100-ns intervals to us, then adjust */
ts = (TimestampTz) (tms / 10) -
((uint64) POSTGRES_EPOCH_JDATE - UUIDV1_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC;
PG_RETURN_TIMESTAMPTZ(ts);
}
/* not a timestamp-containing UUID version */
PG_RETURN_NULL();
}
/*
* Extract UUID version.
*
* Returns null if not RFC 4122 variant.
*/
Datum
uuid_extract_version(PG_FUNCTION_ARGS)
{
pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
uint16 version;
/* check if RFC 4122 variant */
if ((uuid->data[8] & 0xc0) != 0x80)
PG_RETURN_NULL();
version = uuid->data[6] >> 4;
PG_RETURN_UINT16(version);
}