database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-19 15:49:24 +03:00
Code Activity

Optionally disable subscriptions on error.

Browse Source 
Logical replication apply workers for a subscription can easily get stuck
in an infinite loop of attempting to apply a change, triggering an error
(such as a constraint violation), exiting with the error written to the
subscription server log, and restarting.

To partially remedy the situation, this patch adds a new subscription
option named 'disable_on_error'. To be consistent with old behavior, this
option defaults to false. When true, both the tablesync worker and apply
worker catch any errors thrown and disable the subscription in order to
break the loop. The error is still also written in the logs.

Once the subscription is disabled, users can either manually resolve the
conflict/error or skip the conflicting transaction by using
pg_replication_origin_advance() function. After resolving the conflict,
users need to enable the subscription to allow apply process to proceed.

Author: Osumi Takamichi and Mark Dilger
Reviewed-by: Greg Nancarrow, Vignesh C, Amit Kapila, Wang wei, Tang Haiying, Peter Smith, Masahiko Sawada, Shi Yu
Discussion : https://postgr.es/m/DB35438F-9356-4841-89A0-412709EBD3AB%40enterprisedb.com
This commit is contained in:
Amit Kapila
2022-03-14 09:32:40 +05:30
parent 369398ed88
commit 705e20f855
17 changed files with 421 additions and 108 deletions
Download Patch File Download Diff File Expand all files Collapse all files

162
src/backend/replication/logical/worker.c
View File

@@ -305,6 +305,8 @@ static void store_flush_position(XLogRecPtr remote_lsn);
static void maybe_reread_subscription(void);
static void DisableSubscriptionAndExit(void);
/* prototype needed because of stream_commit */
static void apply_dispatch(StringInfo s);
@@ -3374,6 +3376,84 @@ TwoPhaseTransactionGid(Oid subid, TransactionId xid, char *gid, int szgid)
snprintf(gid, szgid, "pg_gid_%u_%u", subid, xid);
}
/*
* Execute the initial sync with error handling. Disable the subscription,
* if it's required.
*
* Allocate the slot name in long-lived context on return. Note that we don't
* handle FATAL errors which are probably because of system resource error and
* are not repeatable.
*/
static void
start_table_sync(XLogRecPtr *origin_startpos, char **myslotname)
{
char *syncslotname;
Assert(am_tablesync_worker());
PG_TRY();
{
/* Call initial sync. */
syncslotname = LogicalRepSyncTableStart(origin_startpos);
}
PG_CATCH();
{
if (MySubscription->disableonerr)
DisableSubscriptionAndExit();
else
{
/*
* Report the worker failed during table synchronization. Abort
* the current transaction so that the stats message is sent in an
* idle state.
*/
AbortOutOfAnyTransaction();
pgstat_report_subscription_error(MySubscription->oid, false);
PG_RE_THROW();
}
}
PG_END_TRY();
/* allocate slot name in long-lived context */
*myslotname = MemoryContextStrdup(ApplyContext, syncslotname);
pfree(syncslotname);
}
/*
* Run the apply loop with error handling. Disable the subscription,
* if necessary.
*
* Note that we don't handle FATAL errors which are probably because
* of system resource error and are not repeatable.
*/
static void
start_apply(XLogRecPtr origin_startpos)
{
PG_TRY();
{
LogicalRepApplyLoop(origin_startpos);
}
PG_CATCH();
{
if (MySubscription->disableonerr)
DisableSubscriptionAndExit();
else
{
/*
* Report the worker failed while applying changes. Abort the
* current transaction so that the stats message is sent in an
* idle state.
*/
AbortOutOfAnyTransaction();
pgstat_report_subscription_error(MySubscription->oid, !am_tablesync_worker());
PG_RE_THROW();
}
}
PG_END_TRY();
}
/* Logical Replication Apply worker entry point */
void
ApplyWorkerMain(Datum main_arg)
@@ -3381,8 +3461,8 @@ ApplyWorkerMain(Datum main_arg)
int worker_slot = DatumGetInt32(main_arg);
MemoryContext oldctx;
char originname[NAMEDATALEN];
XLogRecPtr origin_startpos;
char *myslotname;
XLogRecPtr origin_startpos = InvalidXLogRecPtr;
char *myslotname = NULL;
WalRcvStreamOptions options;
int server_version;
@@ -3477,32 +3557,7 @@ ApplyWorkerMain(Datum main_arg)
if (am_tablesync_worker())
{
char *syncslotname;
PG_TRY();
{
/* This is table synchronization worker, call initial sync. */
syncslotname = LogicalRepSyncTableStart(&origin_startpos);
}
PG_CATCH();
{
/*
* Abort the current transaction so that we send the stats message
* in an idle state.
*/
AbortOutOfAnyTransaction();
/* Report the worker failed during table synchronization */
pgstat_report_subscription_error(MySubscription->oid, false);
PG_RE_THROW();
}
PG_END_TRY();
/* allocate slot name in long-lived context */
myslotname = MemoryContextStrdup(ApplyContext, syncslotname);
pfree(syncslotname);
start_table_sync(&origin_startpos, &myslotname);
/*
* Allocate the origin name in long-lived context for error context
@@ -3633,24 +3688,43 @@ ApplyWorkerMain(Datum main_arg)
}
/* Run the main loop. */
PG_TRY();
{
LogicalRepApplyLoop(origin_startpos);
}
PG_CATCH();
{
/*
* Abort the current transaction so that we send the stats message in
* an idle state.
*/
AbortOutOfAnyTransaction();
start_apply(origin_startpos);
/* Report the worker failed while applying changes */
pgstat_report_subscription_error(MySubscription->oid, !am_tablesync_worker());
proc_exit(0);
}
PG_RE_THROW();
}
PG_END_TRY();
/*
* After error recovery, disable the subscription in a new transaction
* and exit cleanly.
*/
static void
DisableSubscriptionAndExit(void)
{
/*
* Emit the error message, and recover from the error state to an idle
* state
*/
HOLD_INTERRUPTS();
EmitErrorReport();
AbortOutOfAnyTransaction();
FlushErrorState();
RESUME_INTERRUPTS();
/* Report the worker failed during either table synchronization or apply */
pgstat_report_subscription_error(MyLogicalRepWorker->subid,
!am_tablesync_worker());
/* Disable the subscription */
StartTransactionCommand();
DisableSubscription(MySubscription->oid);
CommitTransactionCommand();
/* Notify the subscription has been disabled and exit */
ereport(LOG,
errmsg("logical replication subscription \"%s\" has been disabled due to an error",
MySubscription->name));
proc_exit(0);
}