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* [PATCH v52 3/7] Make archiver process an auxiliary process
@ 2020-03-13 07:59 Kyotaro Horiguchi <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Kyotaro Horiguchi @ 2020-03-13 07:59 UTC (permalink / raw)
This is a preliminary patch for shared-memory based stats collector.
Archiver process must be a auxiliary process since it uses shared
memory after stats data was moved into shared-memory. Make the process
an auxiliary process in order to make it work.
---
src/backend/access/transam/xlogarchive.c | 6 +-
src/backend/bootstrap/bootstrap.c | 22 ++-
src/backend/postmaster/pgarch.c | 224 ++++++++---------------
src/backend/postmaster/postmaster.c | 83 ++++-----
src/backend/storage/ipc/ipci.c | 2 +
src/include/miscadmin.h | 2 +
src/include/postmaster/pgarch.h | 13 +-
src/include/storage/pmsignal.h | 1 -
src/include/storage/proc.h | 8 +-
9 files changed, 139 insertions(+), 222 deletions(-)
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 1c5a4f8b5a..2558bcfb08 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -25,11 +25,13 @@
#include "common/archive.h"
#include "miscadmin.h"
#include "postmaster/startup.h"
+#include "postmaster/pgarch.h"
#include "replication/walsender.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/lwlock.h"
-#include "storage/pmsignal.h"
+#include "storage/latch.h"
+#include "storage/proc.h"
/*
* Attempt to retrieve the specified file from off-line archival storage.
@@ -491,7 +493,7 @@ XLogArchiveNotify(const char *xlog)
/* Notify archiver that it's got something to do */
if (IsUnderPostmaster)
- SendPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER);
+ PgArchWakeup();
}
/*
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6f615e6622..41da0c5059 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -317,6 +317,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
case StartupProcess:
MyBackendType = B_STARTUP;
break;
+ case ArchiverProcess:
+ MyBackendType = B_ARCHIVER;
+ break;
case BgWriterProcess:
MyBackendType = B_BG_WRITER;
break;
@@ -437,30 +440,29 @@ AuxiliaryProcessMain(int argc, char *argv[])
proc_exit(1); /* should never return */
case StartupProcess:
- /* don't set signals, startup process has its own agenda */
StartupProcessMain();
- proc_exit(1); /* should never return */
+ proc_exit(1);
+
+ case ArchiverProcess:
+ PgArchiverMain();
+ proc_exit(1);
case BgWriterProcess:
- /* don't set signals, bgwriter has its own agenda */
BackgroundWriterMain();
- proc_exit(1); /* should never return */
+ proc_exit(1);
case CheckpointerProcess:
- /* don't set signals, checkpointer has its own agenda */
CheckpointerMain();
- proc_exit(1); /* should never return */
+ proc_exit(1);
case WalWriterProcess:
- /* don't set signals, walwriter has its own agenda */
InitXLOGAccess();
WalWriterMain();
- proc_exit(1); /* should never return */
+ proc_exit(1);
case WalReceiverProcess:
- /* don't set signals, walreceiver has its own agenda */
WalReceiverMain();
- proc_exit(1); /* should never return */
+ proc_exit(1);
default:
elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index edec311f12..c399e6c267 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -38,16 +38,14 @@
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
-#include "postmaster/fork_process.h"
#include "postmaster/interrupt.h"
#include "postmaster/pgarch.h"
-#include "postmaster/postmaster.h"
-#include "storage/dsm.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/latch.h"
-#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
+#include "storage/procsignal.h"
+#include "storage/spin.h"
#include "utils/guc.h"
#include "utils/ps_status.h"
@@ -73,153 +71,68 @@
*/
#define NUM_ORPHAN_CLEANUP_RETRIES 3
+/* Shared memory area for archiver process */
+typedef struct PgArchData
+{
+ Latch *latch; /* latch to wake the archiver up */
+ slock_t mutex; /* locks this struct */
+} PgArchData;
+
/* ----------
* Local data
* ----------
*/
-static time_t last_pgarch_start_time;
static time_t last_sigterm_time = 0;
+PgArchData *PgArch = NULL;
/*
* Flags set by interrupt handlers for later service in the main loop.
*/
-static volatile sig_atomic_t wakened = false;
static volatile sig_atomic_t ready_to_stop = false;
/* ----------
* Local function forward declarations
* ----------
*/
-#ifdef EXEC_BACKEND
-static pid_t pgarch_forkexec(void);
-#endif
-
-NON_EXEC_STATIC void PgArchiverMain(int argc, char *argv[]) pg_attribute_noreturn();
-static void pgarch_waken(SIGNAL_ARGS);
static void pgarch_waken_stop(SIGNAL_ARGS);
static void pgarch_MainLoop(void);
static void pgarch_ArchiverCopyLoop(void);
static bool pgarch_archiveXlog(char *xlog);
static bool pgarch_readyXlog(char *xlog);
static void pgarch_archiveDone(char *xlog);
+static void pgarch_die(int code, Datum arg);
+/* Report shared memory space needed by PgArchShmemInit */
+Size
+PgArchShmemSize(void)
+{
+ Size size = 0;
-/* ------------------------------------------------------------
- * Public functions called from postmaster follow
- * ------------------------------------------------------------
- */
+ size = add_size(size, sizeof(PgArchData));
-/*
- * pgarch_start
- *
- * Called from postmaster at startup or after an existing archiver
- * died. Attempt to fire up a fresh archiver process.
- *
- * Returns PID of child process, or 0 if fail.
- *
- * Note: if fail, we will be called again from the postmaster main loop.
- */
-int
-pgarch_start(void)
-{
- time_t curtime;
- pid_t pgArchPid;
+ return size;
+}
- /*
- * Do nothing if no archiver needed
- */
- if (!XLogArchivingActive())
- return 0;
+/* Allocate and initialize archiver-related shared memory */
+void
+PgArchShmemInit(void)
+{
+ bool found;
- /*
- * Do nothing if too soon since last archiver start. This is a safety
- * valve to protect against continuous respawn attempts if the archiver is
- * dying immediately at launch. Note that since we will be re-called from
- * the postmaster main loop, we will get another chance later.
- */
- curtime = time(NULL);
- if ((unsigned int) (curtime - last_pgarch_start_time) <
- (unsigned int) PGARCH_RESTART_INTERVAL)
- return 0;
- last_pgarch_start_time = curtime;
+ PgArch = (PgArchData *)
+ ShmemInitStruct("Archiver ", PgArchShmemSize(), &found);
-#ifdef EXEC_BACKEND
- switch ((pgArchPid = pgarch_forkexec()))
-#else
- switch ((pgArchPid = fork_process()))
-#endif
+ if (!found)
{
- case -1:
- ereport(LOG,
- (errmsg("could not fork archiver: %m")));
- return 0;
-
-#ifndef EXEC_BACKEND
- case 0:
- /* in postmaster child ... */
- InitPostmasterChild();
-
- /* Close the postmaster's sockets */
- ClosePostmasterPorts(false);
-
- /* Drop our connection to postmaster's shared memory, as well */
- dsm_detach_all();
- PGSharedMemoryDetach();
-
- PgArchiverMain(0, NULL);
- break;
-#endif
-
- default:
- return (int) pgArchPid;
+ SpinLockInit(&PgArch->mutex);
+ PgArch->latch = NULL;
}
-
- /* shouldn't get here */
- return 0;
-}
-
-/* ------------------------------------------------------------
- * Local functions called by archiver follow
- * ------------------------------------------------------------
- */
-
-
-#ifdef EXEC_BACKEND
-
-/*
- * pgarch_forkexec() -
- *
- * Format up the arglist for, then fork and exec, archive process
- */
-static pid_t
-pgarch_forkexec(void)
-{
- char *av[10];
- int ac = 0;
-
- av[ac++] = "postgres";
-
- av[ac++] = "--forkarch";
-
- av[ac++] = NULL; /* filled in by postmaster_forkexec */
-
- av[ac] = NULL;
- Assert(ac < lengthof(av));
-
- return postmaster_forkexec(ac, av);
}
-#endif /* EXEC_BACKEND */
-
-/*
- * PgArchiverMain
- *
- * The argc/argv parameters are valid only in EXEC_BACKEND case. However,
- * since we don't use 'em, it hardly matters...
- */
-NON_EXEC_STATIC void
-PgArchiverMain(int argc, char *argv[])
+/* Main entry point for archiver process */
+void
+PgArchiverMain(void)
{
/*
* Ignore all signals usually bound to some action in the postmaster,
@@ -231,33 +144,48 @@ PgArchiverMain(int argc, char *argv[])
/* SIGQUIT handler was already set up by InitPostmasterChild */
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
- pqsignal(SIGUSR1, pgarch_waken);
+ pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, pgarch_waken_stop);
+
/* Reset some signals that are accepted by postmaster but not here */
pqsignal(SIGCHLD, SIG_DFL);
+
+ /* Unblock signals (they were blocked when the postmaster forked us) */
PG_SETMASK(&UnBlockSig);
- MyBackendType = B_ARCHIVER;
- init_ps_display(NULL);
+ /* Arrange to clean up at archiver exit */
+ on_shmem_exit(pgarch_die, 0);
+
+ /*
+ * Advertise our latch that backends can use to wake us up while we're
+ * sleeping.
+ */
+ SpinLockAcquire(&PgArch->mutex);
+ PgArch->latch = MyLatch;
+ SpinLockRelease(&PgArch->mutex);
pgarch_MainLoop();
- exit(0);
+ proc_exit(0);
}
-/* SIGUSR1 signal handler for archiver process */
-static void
-pgarch_waken(SIGNAL_ARGS)
+/*
+ * Wake up the archiver
+ */
+void
+PgArchWakeup(void)
{
- int save_errno = errno;
+ Latch *latch;
- /* set flag that there is work to be done */
- wakened = true;
- SetLatch(MyLatch);
+ SpinLockAcquire(&PgArch->mutex);
+ latch = PgArch->latch;
+ SpinLockRelease(&PgArch->mutex);
- errno = save_errno;
+ if (latch)
+ SetLatch(latch);
}
+
/* SIGUSR2 signal handler for archiver process */
static void
pgarch_waken_stop(SIGNAL_ARGS)
@@ -282,14 +210,6 @@ pgarch_MainLoop(void)
pg_time_t last_copy_time = 0;
bool time_to_stop;
- /*
- * We run the copy loop immediately upon entry, in case there are
- * unarchived files left over from a previous database run (or maybe the
- * archiver died unexpectedly). After that we wait for a signal or
- * timeout before doing more.
- */
- wakened = true;
-
/*
* There shouldn't be anything for the archiver to do except to wait for a
* signal ... however, the archiver exists to protect our data, so she
@@ -328,12 +248,8 @@ pgarch_MainLoop(void)
}
/* Do what we're here for */
- if (wakened || time_to_stop)
- {
- wakened = false;
- pgarch_ArchiverCopyLoop();
- last_copy_time = time(NULL);
- }
+ pgarch_ArchiverCopyLoop();
+ last_copy_time = time(NULL);
/*
* Sleep until a signal is received, or until a poll is forced by
@@ -354,13 +270,9 @@ pgarch_MainLoop(void)
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
timeout * 1000L,
WAIT_EVENT_ARCHIVER_MAIN);
- if (rc & WL_TIMEOUT)
- wakened = true;
if (rc & WL_POSTMASTER_DEATH)
time_to_stop = true;
}
- else
- wakened = true;
}
/*
@@ -744,3 +656,17 @@ pgarch_archiveDone(char *xlog)
StatusFilePath(rlogdone, xlog, ".done");
(void) durable_rename(rlogready, rlogdone, WARNING);
}
+
+
+/*
+ * pgarch_die
+ *
+ * exit-time cleanup handler
+ */
+static void
+pgarch_die(int code, Datum arg)
+{
+ SpinLockAcquire(&PgArch->mutex);
+ PgArch->latch = NULL;
+ SpinLockRelease(&PgArch->mutex);
+}
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index edab95a19e..34c8551288 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -548,6 +548,7 @@ static void ShmemBackendArrayRemove(Backend *bn);
#endif /* EXEC_BACKEND */
#define StartupDataBase() StartChildProcess(StartupProcess)
+#define StartArchiver() StartChildProcess(ArchiverProcess)
#define StartBackgroundWriter() StartChildProcess(BgWriterProcess)
#define StartCheckpointer() StartChildProcess(CheckpointerProcess)
#define StartWalWriter() StartChildProcess(WalWriterProcess)
@@ -1792,7 +1793,7 @@ ServerLoop(void)
/* If we have lost the archiver, try to start a new one. */
if (PgArchPID == 0 && PgArchStartupAllowed())
- PgArchPID = pgarch_start();
+ PgArchPID = StartArchiver();
/* If we need to signal the autovacuum launcher, do so now */
if (avlauncher_needs_signal)
@@ -3007,7 +3008,7 @@ reaper(SIGNAL_ARGS)
if (!IsBinaryUpgrade && AutoVacuumingActive() && AutoVacPID == 0)
AutoVacPID = StartAutoVacLauncher();
if (PgArchStartupAllowed() && PgArchPID == 0)
- PgArchPID = pgarch_start();
+ PgArchPID = StartArchiver();
if (PgStatPID == 0)
PgStatPID = pgstat_start();
@@ -3141,24 +3142,6 @@ reaper(SIGNAL_ARGS)
continue;
}
- /*
- * Was it the archiver? If so, just try to start a new one; no need
- * to force reset of the rest of the system. (If fail, we'll try
- * again in future cycles of the main loop.). Unless we were waiting
- * for it to shut down; don't restart it in that case, and
- * PostmasterStateMachine() will advance to the next shutdown step.
- */
- if (pid == PgArchPID)
- {
- PgArchPID = 0;
- if (!EXIT_STATUS_0(exitstatus))
- LogChildExit(LOG, _("archiver process"),
- pid, exitstatus);
- if (PgArchStartupAllowed())
- PgArchPID = pgarch_start();
- continue;
- }
-
/*
* Was it the statistics collector? If so, just try to start a new
* one; no need to force reset of the rest of the system. (If fail,
@@ -3175,6 +3158,26 @@ reaper(SIGNAL_ARGS)
continue;
}
+ /*
+ * Was it the archiver? If exit status is zero (normal) or one (FATAL
+ * exit), we assume everything is all right just like normal backends
+ * and just try to restart a new one so that we immediately retry
+ * archiving remaining files. (If fail, we'll try again in future
+ * cycles of the postmaster's main loop.) Unless we were waiting for it
+ * to shut down; don't restart it in that case, and
+ * PostmasterStateMachine() will advance to the next shutdown step.
+ */
+ if (pid == PgArchPID)
+ {
+ PgArchPID = 0;
+ if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
+ HandleChildCrash(pid, exitstatus,
+ _("archiver process"));
+ if (PgArchStartupAllowed())
+ PgArchPID = StartArchiver();
+ continue;
+ }
+
/* Was it the system logger? If so, try to start a new one */
if (pid == SysLoggerPID)
{
@@ -3403,7 +3406,7 @@ CleanupBackend(int pid,
/*
* HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer,
- * walwriter, autovacuum, or background worker.
+ * walwriter, autovacuum, archiver or background worker.
*
* The objectives here are to clean up our local state about the child
* process, and to signal all other remaining children to quickdie.
@@ -3609,19 +3612,16 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
signal_child(AutoVacPID, (SendStop ? SIGSTOP : SIGQUIT));
}
- /*
- * Force a power-cycle of the pgarch process too. (This isn't absolutely
- * necessary, but it seems like a good idea for robustness, and it
- * simplifies the state-machine logic in the case where a shutdown request
- * arrives during crash processing.)
- */
- if (PgArchPID != 0 && take_action)
+ /* Take care of the archiver too */
+ if (pid == PgArchPID)
+ PgArchPID = 0;
+ else if (PgArchPID != 0 && take_action)
{
ereport(DEBUG2,
(errmsg_internal("sending %s to process %d",
- "SIGQUIT",
+ (SendStop ? "SIGSTOP" : "SIGQUIT"),
(int) PgArchPID)));
- signal_child(PgArchPID, SIGQUIT);
+ signal_child(PgArchPID, (SendStop ? SIGSTOP : SIGQUIT));
}
/*
@@ -3912,6 +3912,7 @@ PostmasterStateMachine(void)
Assert(CheckpointerPID == 0);
Assert(WalWriterPID == 0);
Assert(AutoVacPID == 0);
+ Assert(PgArchPID == 0);
/* syslogger is not considered here */
pmState = PM_NO_CHILDREN;
}
@@ -5037,12 +5038,6 @@ SubPostmasterMain(int argc, char *argv[])
StartBackgroundWorker();
}
- if (strcmp(argv[1], "--forkarch") == 0)
- {
- /* Do not want to attach to shared memory */
-
- PgArchiverMain(argc, argv); /* does not return */
- }
if (strcmp(argv[1], "--forkcol") == 0)
{
/* Do not want to attach to shared memory */
@@ -5140,7 +5135,7 @@ sigusr1_handler(SIGNAL_ARGS)
*/
Assert(PgArchPID == 0);
if (XLogArchivingAlways())
- PgArchPID = pgarch_start();
+ PgArchPID = StartArchiver();
/*
* If we aren't planning to enter hot standby mode later, treat
@@ -5194,16 +5189,6 @@ sigusr1_handler(SIGNAL_ARGS)
if (StartWorkerNeeded || HaveCrashedWorker)
maybe_start_bgworkers();
- if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) &&
- PgArchPID != 0)
- {
- /*
- * Send SIGUSR1 to archiver process, to wake it up and begin archiving
- * next WAL file.
- */
- signal_child(PgArchPID, SIGUSR1);
- }
-
/* Tell syslogger to rotate logfile if requested */
if (SysLoggerPID != 0)
{
@@ -5445,6 +5430,10 @@ StartChildProcess(AuxProcType type)
ereport(LOG,
(errmsg("could not fork startup process: %m")));
break;
+ case ArchiverProcess:
+ ereport(LOG,
+ (errmsg("could not fork archiver process: %m")));
+ break;
case BgWriterProcess:
ereport(LOG,
(errmsg("could not fork background writer process: %m")));
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index f9bbe97b50..3e4ec53a97 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -144,6 +144,7 @@ CreateSharedMemoryAndSemaphores(void)
size = add_size(size, ReplicationOriginShmemSize());
size = add_size(size, WalSndShmemSize());
size = add_size(size, WalRcvShmemSize());
+ size = add_size(size, PgArchShmemSize());
size = add_size(size, ApplyLauncherShmemSize());
size = add_size(size, SnapMgrShmemSize());
size = add_size(size, BTreeShmemSize());
@@ -258,6 +259,7 @@ CreateSharedMemoryAndSemaphores(void)
ReplicationOriginShmemInit();
WalSndShmemInit();
WalRcvShmemInit();
+ PgArchShmemInit();
ApplyLauncherShmemInit();
/*
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 1bdc97e308..adb9f819bb 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -419,6 +419,7 @@ typedef enum
BootstrapProcess,
StartupProcess,
BgWriterProcess,
+ ArchiverProcess,
CheckpointerProcess,
WalWriterProcess,
WalReceiverProcess,
@@ -431,6 +432,7 @@ extern AuxProcType MyAuxProcType;
#define AmBootstrapProcess() (MyAuxProcType == BootstrapProcess)
#define AmStartupProcess() (MyAuxProcType == StartupProcess)
#define AmBackgroundWriterProcess() (MyAuxProcType == BgWriterProcess)
+#define AmArchiverProcess() (MyAuxProcType == ArchiverProcess)
#define AmCheckpointerProcess() (MyAuxProcType == CheckpointerProcess)
#define AmWalWriterProcess() (MyAuxProcType == WalWriterProcess)
#define AmWalReceiverProcess() (MyAuxProcType == WalReceiverProcess)
diff --git a/src/include/postmaster/pgarch.h b/src/include/postmaster/pgarch.h
index d102a21ab7..d053bf1564 100644
--- a/src/include/postmaster/pgarch.h
+++ b/src/include/postmaster/pgarch.h
@@ -26,14 +26,9 @@
#define MAX_XFN_CHARS 40
#define VALID_XFN_CHARS "0123456789ABCDEF.history.backup.partial"
-/* ----------
- * Functions called from postmaster
- * ----------
- */
-extern int pgarch_start(void);
-
-#ifdef EXEC_BACKEND
-extern void PgArchiverMain(int argc, char *argv[]) pg_attribute_noreturn();
-#endif
+extern Size PgArchShmemSize(void);
+extern void PgArchShmemInit(void);
+extern void PgArchiverMain(void) pg_attribute_noreturn();
+extern void PgArchWakeup(void);
#endif /* _PGARCH_H */
diff --git a/src/include/storage/pmsignal.h b/src/include/storage/pmsignal.h
index dbbed18f61..8ed4d87ae6 100644
--- a/src/include/storage/pmsignal.h
+++ b/src/include/storage/pmsignal.h
@@ -34,7 +34,6 @@ typedef enum
{
PMSIGNAL_RECOVERY_STARTED, /* recovery has started */
PMSIGNAL_BEGIN_HOT_STANDBY, /* begin Hot Standby */
- PMSIGNAL_WAKEN_ARCHIVER, /* send a NOTIFY signal to xlog archiver */
PMSIGNAL_ROTATE_LOGFILE, /* send SIGUSR1 to syslogger to rotate logfile */
PMSIGNAL_START_AUTOVAC_LAUNCHER, /* start an autovacuum launcher */
PMSIGNAL_START_AUTOVAC_WORKER, /* start an autovacuum worker */
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index a777cb64a1..2fd1ff09a7 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -370,11 +370,11 @@ extern PGPROC *PreparedXactProcs;
* We set aside some extra PGPROC structures for auxiliary processes,
* ie things that aren't full-fledged backends but need shmem access.
*
- * Background writer, checkpointer and WAL writer run during normal operation.
- * Startup process and WAL receiver also consume 2 slots, but WAL writer is
- * launched only after startup has exited, so we only need 4 slots.
+ * Background writer, checkpointer, WAL writer and archiver run during normal
+ * operation. Startup process and WAL receiver also consume 2 slots, but WAL
+ * writer is launched only after startup has exited, so we only need 5 slots.
*/
-#define NUM_AUXILIARY_PROCS 4
+#define NUM_AUXILIARY_PROCS 5
/* configurable options */
extern PGDLLIMPORT int DeadlockTimeout;
--
2.27.0
----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
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Content-Transfer-Encoding: 7bit
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filename="v52-0004-Shared-memory-based-stats-collector.patch"
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: ERROR: corrupt MVNDistinct entry
@ 2024-12-25 02:33 Andrei Lepikhov <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Andrei Lepikhov @ 2024-12-25 02:33 UTC (permalink / raw)
To: Richard Guo <[email protected]>; pgsql-hackers
On 12/24/24 15:00, Richard Guo wrote:
> Any thoughts?
I have a couple of notes.
1. The nulling_relids provides us sensible information about possible
nulls inside the input. We are not using it to estimate the number of
such nulls for now. Does Your idea consist of obtaining 'clear'
statistics and reusing nulling_relids knowledge somewhere later?
2. It is ok for Vars. But what about expressions? We use equal() in
distinct, MCV and dependencies modules. Do we need to remove nulls
before using extended statistics as a general rule?
--
regards, Andrei Lepikhov
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2020-03-13 07:59 [PATCH v52 3/7] Make archiver process an auxiliary process Kyotaro Horiguchi <[email protected]>
2024-12-25 02:33 Re: ERROR: corrupt MVNDistinct entry Andrei Lepikhov <[email protected]>
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