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[PATCH v50 3/7] Make archiver process an auxiliary process 2+ messages / 2 participants [nested] [flat]
* [PATCH v50 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 | 7 +- src/backend/bootstrap/bootstrap.c | 22 +-- src/backend/postmaster/pgarch.c | 174 +++-------------------- src/backend/postmaster/postmaster.c | 88 ++++++------ src/backend/storage/lmgr/proc.c | 1 + src/include/miscadmin.h | 2 + src/include/postmaster/pgarch.h | 10 +- src/include/storage/pmsignal.h | 1 - src/include/storage/proc.h | 10 +- 9 files changed, 83 insertions(+), 232 deletions(-) diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c index 1c5a4f8b5a..8b66a30931 100644 --- a/src/backend/access/transam/xlogarchive.c +++ b/src/backend/access/transam/xlogarchive.c @@ -29,7 +29,8 @@ #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. @@ -490,8 +491,8 @@ XLogArchiveNotify(const char *xlog) } /* Notify archiver that it's got something to do */ - if (IsUnderPostmaster) - SendPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER); + if (IsUnderPostmaster && ProcGlobal->archiverLatch) + SetLatch(ProcGlobal->archiverLatch); } /* 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..e237cedaff 100644 --- a/src/backend/postmaster/pgarch.c +++ b/src/backend/postmaster/pgarch.c @@ -48,6 +48,7 @@ #include "storage/latch.h" #include "storage/pg_shmem.h" #include "storage/pmsignal.h" +#include "storage/procsignal.h" #include "utils/guc.h" #include "utils/ps_status.h" @@ -78,25 +79,17 @@ * Local data * ---------- */ -static time_t last_pgarch_start_time; static time_t last_sigterm_time = 0; /* * 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); @@ -105,121 +98,9 @@ static bool pgarch_readyXlog(char *xlog); static void pgarch_archiveDone(char *xlog); -/* ------------------------------------------------------------ - * Public functions called from postmaster follow - * ------------------------------------------------------------ - */ - -/* - * 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; - - /* - * Do nothing if no archiver needed - */ - if (!XLogArchivingActive()) - return 0; - - /* - * 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; - -#ifdef EXEC_BACKEND - switch ((pgArchPid = pgarch_forkexec())) -#else - switch ((pgArchPid = fork_process())) -#endif - { - 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; - } - - /* 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, @@ -231,31 +112,24 @@ 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); + /* + * Advertise our latch that backends can use to wake us up while we're + * sleeping. + */ + ProcGlobal->archiverLatch = &MyProc->procLatch; pgarch_MainLoop(); - exit(0); -} - -/* SIGUSR1 signal handler for archiver process */ -static void -pgarch_waken(SIGNAL_ARGS) -{ - int save_errno = errno; - - /* set flag that there is work to be done */ - wakened = true; - SetLatch(MyLatch); - - errno = save_errno; + proc_exit(0); } /* SIGUSR2 signal handler for archiver process */ @@ -282,14 +156,6 @@ 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 +194,8 @@ 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 +216,9 @@ 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; } /* diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index edab95a19e..d9f8d82650 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(); @@ -3126,6 +3127,18 @@ reaper(SIGNAL_ARGS) continue; } + /* + * Was it the archiver? We treat it the same way to WAL receiver. + */ + if (pid == PgArchPID) + { + PgArchPID = 0; + if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("archiver process")); + continue; + } + /* * Was it the autovacuum launcher? Normal exit can be ignored; we'll * start a new one at the next iteration of the postmaster's main @@ -3141,24 +3154,6 @@ 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, @@ -3403,7 +3398,7 @@ 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 +3604,16 @@ 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 +3904,7 @@ PostmasterStateMachine(void) Assert(CheckpointerPID == 0); Assert(WalWriterPID == 0); Assert(AutoVacPID == 0); + Assert(PgArchPID == 0); /* syslogger is not considered here */ pmState = PM_NO_CHILDREN; } @@ -4989,6 +4982,19 @@ SubPostmasterMain(int argc, char *argv[]) AuxiliaryProcessMain(argc - 2, argv + 2); /* does not return */ } + if (strcmp(argv[1], "--forkarch") == 0) + { + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitAuxiliaryProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + PgArchiverMain(); /* does not return */ + } if (strcmp(argv[1], "--forkavlauncher") == 0) { /* Restore basic shared memory pointers */ @@ -5037,12 +5043,6 @@ 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 +5140,7 @@ 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 +5194,6 @@ 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 +5435,10 @@ 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/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 897045ee27..bf5d6da89b 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -182,6 +182,7 @@ InitProcGlobal(void) ProcGlobal->startupBufferPinWaitBufId = -1; ProcGlobal->walwriterLatch = NULL; ProcGlobal->checkpointerLatch = NULL; + ProcGlobal->archiverLatch = NULL; pg_atomic_init_u32(&ProcGlobal->procArrayGroupFirst, INVALID_PGPROCNO); pg_atomic_init_u32(&ProcGlobal->clogGroupFirst, INVALID_PGPROCNO); 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..737ed69e57 100644 --- a/src/include/postmaster/pgarch.h +++ b/src/include/postmaster/pgarch.h @@ -26,14 +26,6 @@ #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 void PgArchiverMain(void) pg_attribute_noreturn(); #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..d73890b228 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -357,6 +357,8 @@ typedef struct PROC_HDR int startupProcPid; /* Buffer id of the buffer that Startup process waits for pin on, or -1 */ int startupBufferPinWaitBufId; + /* Archiver process's latch */ + Latch *archiverLatch; } PROC_HDR; extern PGDLLIMPORT PROC_HDR *ProcGlobal; @@ -370,11 +372,11 @@ 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(Tue_Mar__9_18_29_34_2021_806)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v50-0004-Shared-memory-based-stats-collector.patch" ^ permalink raw reply [nested|flat] 2+ messages in thread
* ExecAggTransReparent is underdocumented and badly named @ 2023-04-19 18:50 Tom Lane <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2023-04-19 18:50 UTC (permalink / raw) To: [email protected] I wondered at [1] why ExecAggTransReparent doesn't do what you'd guess from the name, that is reparent a supplied R/W expanded object under the aggcontext even if it's not there already. I tried to make it do that, and after I'd finished bandaging my wounds, I wrote some commentary explaining why that won't work. (Possibly we knew this at some point, but if so we sure failed to provide documentation about it.) I think we should at least apply the attached commentary-only patch. I wonder though if we should change the name of this function, and if so to what. Maybe ExecAggCopyTransValue? regards, tom lane [1] https://www.postgresql.org/message-id/2199319.1681662388%40sss.pgh.pa.us Attachments: [text/x-diff] document-ExecAggTransReparent-better.patch (3.9K, ../../[email protected]/2-document-ExecAggTransReparent-better.patch) download | inline diff: diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c index 4cd46f1717..386abf50b3 100644 --- a/src/backend/executor/execExprInterp.c +++ b/src/backend/executor/execExprInterp.c @@ -4341,10 +4341,27 @@ ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup } /* - * Ensure that the current transition value is a child of the aggcontext, + * Ensure that the new transition value is stored in the aggcontext, * rather than the per-tuple context. * * NB: This can change the current memory context. + * + * This function is misnamed. It can either copy the datum returned by + * the transfn, or do nothing if the datum points to a R/W expanded object + * that is already a child of the aggcontext. What it will *not* do is what + * you might guess from the name, that is transfer a R/W expanded object from + * some other context to the aggcontext. We expect that a transfn that deals + * in expanded objects and is aware of the memory management conventions for + * aggregate transition values will have returned a R/W expanded object that + * is already in the right context. However, if we have a generic transfn + * that returns a R/W expanded object in the per-tuple context, we have a + * problem. If we pass that R/W object to the next invocation of the transfn, + * it will be at liberty to change or delete that object, and if it deletes it + * then our own attempt to delete the now-old transvalue afterwards will be a + * double free. We avoid this problem by forcing the transvalue to always + * be a flat non-expanded object unless the transfn is visibly doing + * aggregate-aware memory management. This is somewhat inefficient, but the + * best answer to that is to write a smarter transfn. */ Datum ExecAggTransReparent(AggState *aggstate, AggStatePerTrans pertrans, @@ -4559,9 +4576,7 @@ ExecAggPlainTransByRef(AggState *aggstate, AggStatePerTrans pertrans, /* * For pass-by-ref datatype, must copy the new value into aggcontext and * free the prior transValue. But if transfn returned a pointer to its - * first input, we don't need to do anything. Also, if transfn returned a - * pointer to a R/W expanded object that is already a child of the - * aggcontext, assume we can adopt that value without copying it. + * first input, we don't need to do anything. * * It's safe to compare newVal with pergroup->transValue without regard * for either being NULL, because ExecAggTransReparent() takes care to set diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c index 3ac581a711..75a4f83ff1 100644 --- a/src/backend/executor/nodeWindowAgg.c +++ b/src/backend/executor/nodeWindowAgg.c @@ -368,7 +368,8 @@ advance_windowaggregate(WindowAggState *winstate, * free the prior transValue. But if transfn returned a pointer to its * first input, we don't need to do anything. Also, if transfn returned a * pointer to a R/W expanded object that is already a child of the - * aggcontext, assume we can adopt that value without copying it. + * aggcontext, assume we can adopt that value without copying it. (See + * comments for ExecAggTransReparent, which this code duplicates.) */ if (!peraggstate->transtypeByVal && DatumGetPointer(newVal) != DatumGetPointer(peraggstate->transValue)) @@ -533,7 +534,8 @@ advance_windowaggregate_base(WindowAggState *winstate, * free the prior transValue. But if invtransfn returned a pointer to its * first input, we don't need to do anything. Also, if invtransfn * returned a pointer to a R/W expanded object that is already a child of - * the aggcontext, assume we can adopt that value without copying it. + * the aggcontext, assume we can adopt that value without copying it. (See + * comments for ExecAggTransReparent, which this code duplicates.) * * Note: the checks for null values here will never fire, but it seems * best to have this stanza look just like advance_windowaggregate. ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2023-04-19 18:50 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-03-13 07:59 [PATCH v50 3/7] Make archiver process an auxiliary process Kyotaro Horiguchi <[email protected]> 2023-04-19 18:50 ExecAggTransReparent is underdocumented and badly named Tom Lane <[email protected]>
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