Re: pg_serial early wraparound

The following review has been posted through the commitfest application:
make installcheck-world:  not tested
Implements feature:       not tested
Spec compliant:           not tested
Documentation:            not tested

Hi, I've tried to review this patch, but it seems that I miss something essential.
You claim that SLRUs now support five digit segment name, while in slru.h
at current master I see the following:

 * Note: slru.c currently assumes that segment file names will be four hex
 * digits.  This sets a lower bound on the segment size (64K transactions
 * for 32-bit TransactionIds).
 */
#define SLRU_PAGES_PER_SEGMENT	32

/* Maximum length of an SLRU name */
#define SLRU_MAX_NAME_LENGTH	32

Could you please clarify the idea of the patch? Is it still relevant?

I've also run your test script.
pg_clog was renamed to pg_xact, so it need to be changed accordingly
echo "Contents of pg_clog:"
  ls $PGDATA/pg_xact/


The test shows failed assertion:

========== setting next xid to 1073741824 =========
Transaction log reset
waiting for server to start....2017-03-24 17:05:19.897 MSK [1181] LOG:  listening on IPv4 address "127.0.0.1", port 5432
2017-03-24 17:05:19.981 MSK [1181] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2017-03-24 17:05:20.081 MSK [1183] LOG:  database system was shut down at 2017-03-24 17:05:19 MSK
2017-03-24 17:05:20.221 MSK [1181] LOG:  database system is ready to accept connections
 done
server started
vacuumdb: vacuuming database "postgres"
vacuumdb: vacuuming database "template0"
vacuumdb: vacuuming database "template1"
TRAP: FailedAssertion("!(TransactionIdPrecedesOrEquals(oldestXact, ShmemVariableCache->oldestXid))", File: "clog.c", Line: 669)
vacuumdb: vacuuming of database "template1" failed: server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.
2017-03-24 17:05:21.541 MSK [1181] LOG:  server process (PID 1202) was terminated by signal 6: Aborted
2017-03-24 17:05:21.541 MSK [1181] DETAIL:  Failed process was running: VACUUM (FREEZE);

The new status of this patch is: Waiting on Author