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Allow users to skip logical replication of data having origin.

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This patch adds a new SUBSCRIPTION parameter "origin". It specifies
whether the subscription will request the publisher to only send changes
that don't have an origin or send changes regardless of origin. Setting it
to "none" means that the subscription will request the publisher to only
send changes that have no origin associated. Setting it to "any" means
that the publisher sends changes regardless of their origin. The default
is "any".
Usage:
CREATE SUBSCRIPTION sub1 CONNECTION 'dbname=postgres port=9999'
PUBLICATION pub1 WITH (origin = none);

This can be used to avoid loops (infinite replication of the same data)
among replication nodes.

This feature allows filtering only the replication data originating from
WAL but for initial sync (initial copy of table data) we don't have such a
facility as we can only distinguish the data based on origin from WAL. As
a follow-up patch, we are planning to forbid the initial sync if the
origin is specified as none and we notice that the publication tables were
also replicated from other publishers to avoid duplicate data or loops.

We forbid to allow creating origin with names 'none' and 'any' to avoid
confusion with the same name options.

Author: Vignesh C, Amit Kapila
Reviewed-By: Peter Smith, Amit Kapila, Dilip Kumar, Shi yu, Ashutosh Bapat, Hayato Kuroda
Discussion: https://postgr.es/m/CALDaNm0gwjY_4HFxvvty01BOT01q_fJLKQ3pWP9=9orqubhjcQ@mail.gmail.com
This commit is contained in:
Amit Kapila
2022-07-21 08:47:38 +05:30
parent f2d0c7f18b
commit 366283961a
24 changed files with 463 additions and 78 deletions
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27
src/backend/replication/pgoutput/pgoutput.c
View File

@@ -16,6 +16,7 @@
#include "catalog/partition.h"
#include "catalog/pg_publication.h"
#include "catalog/pg_publication_rel.h"
#include "catalog/pg_subscription.h"
#include "commands/defrem.h"
#include "executor/executor.h"
#include "fmgr.h"
@@ -79,6 +80,7 @@ static void pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
static bool publications_valid;
static bool in_streaming;
static bool publish_no_origin;
static List *LoadPublications(List *pubnames);
static void publication_invalidation_cb(Datum arg, int cacheid,
@@ -285,6 +287,7 @@ parse_output_parameters(List *options, PGOutputData *data)
bool messages_option_given = false;
bool streaming_given = false;
bool two_phase_option_given = false;
bool origin_option_given = false;
data->binary = false;
data->streaming = false;
@@ -378,6 +381,24 @@ parse_output_parameters(List *options, PGOutputData *data)
data->two_phase = defGetBoolean(defel);
}
else if (strcmp(defel->defname, "origin") == 0)
{
if (origin_option_given)
ereport(ERROR,
errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options"));
origin_option_given = true;
data->origin = defGetString(defel);
if (pg_strcasecmp(data->origin, LOGICALREP_ORIGIN_NONE) == 0)
publish_no_origin = true;
else if (pg_strcasecmp(data->origin, LOGICALREP_ORIGIN_ANY) == 0)
publish_no_origin = false;
else
ereport(ERROR,
errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized origin value: \"%s\"", data->origin));
}
else
elog(ERROR, "unrecognized pgoutput option: %s", defel->defname);
}
@@ -1696,12 +1717,16 @@ pgoutput_message(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
}
/*
* Currently we always forward.
* Return true if the data is associated with an origin and the user has
* requested the changes that don't have an origin, false otherwise.
*/
static bool
pgoutput_origin_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id)
{
if (publish_no_origin && origin_id != InvalidRepOriginId)
return true;
return false;
}