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Raise a WARNING for missing publications. 

When we create or alter a subscription to add publications raise a warning
for non-existent publications. We don't want to give an error here because
it is possible that users can later create the missing publications.

Author: Vignesh C
Reviewed-by: Bharath Rupireddy, Japin Li, Dilip Kumar, Euler Taveira, Ashutosh Sharma, Amit Kapila
Discussion: https://postgr.es/m/CALDaNm0f4YujGW+q-Di0CbZpnQKFFrXntikaQQKuEmGG0=Zw=Q@mail.gmail.com
This commit is contained in:
Amit Kapila 2022-03-31 08:24:19 +05:30
parent 8ac4c25a05
commit 8f2e2bbf14
4 changed files with 160 additions and 21 deletions
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4
doc/src/sgml/ref/alter_subscription.sgml
View File

@ -114,7 +114,9 @@ ALTER SUBSCRIPTION <replaceable class="parameter">name</replaceable> RENAME TO <
replaces the entire list of publications with a new list,
<literal>ADD</literal> adds additional publications to the list of
publications, and <literal>DROP</literal> removes the publications from
the list of publications. See <xref linkend="sql-createsubscription"/>
the list of publications. We allow non-existent publications to be
specified in <literal>ADD</literal> and <literal>SET</literal> variants
so that users can add those later. See <xref linkend="sql-createsubscription"/>
for more information. By default, this command will also act like
<literal>REFRESH PUBLICATION</literal>.
</para>

7
doc/src/sgml/ref/create_subscription.sgml
View File

@ -356,6 +356,13 @@ CREATE SUBSCRIPTION <replaceable class="parameter">subscription_name</replaceabl
copied data that would be incompatible with subsequent filtering.
</para>
<para>
We allow non-existent publications to be specified so that users can add
those later. This means
<link linkend="catalog-pg-subscription"><structname>pg_subscription</structname></link>
can have non-existent publications.
</para>
</refsect1>
<refsect1>

133
src/backend/commands/subscriptioncmds.c
View File

@ -375,6 +375,103 @@ parse_subscription_options(ParseState *pstate, List *stmt_options,
}
}
/*
* Add publication names from the list to a string.
*/
static void
get_publications_str(List *publications, StringInfo dest, bool quote_literal)
{
ListCell *lc;
bool first = true;
Assert(list_length(publications) > 0);
foreach(lc, publications)
{
char *pubname = strVal(lfirst(lc));
if (first)
first = false;
else
appendStringInfoString(dest, ", ");
if (quote_literal)
appendStringInfoString(dest, quote_literal_cstr(pubname));
else
{
appendStringInfoChar(dest, '"');
appendStringInfoString(dest, pubname);
appendStringInfoChar(dest, '"');
}
}
}
/*
* Check the specified publication(s) is(are) present in the publisher.
*/
static void
check_publications(WalReceiverConn *wrconn, List *publications)
{
WalRcvExecResult *res;
StringInfo cmd;
TupleTableSlot *slot;
List *publicationsCopy = NIL;
Oid tableRow[1] = {TEXTOID};
cmd = makeStringInfo();
appendStringInfoString(cmd, "SELECT t.pubname FROM\n"
" pg_catalog.pg_publication t WHERE\n"
" t.pubname IN (");
get_publications_str(publications, cmd, true);
appendStringInfoChar(cmd, ')');
res = walrcv_exec(wrconn, cmd->data, 1, tableRow);
pfree(cmd->data);
pfree(cmd);
if (res->status != WALRCV_OK_TUPLES)
ereport(ERROR,
errmsg_plural("could not receive publication from the publisher: %s",
"could not receive list of publications from the publisher: %s",
list_length(publications),
res->err));
publicationsCopy = list_copy(publications);
/* Process publication(s). */
slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
{
char *pubname;
bool isnull;
pubname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
Assert(!isnull);
/* Delete the publication present in publisher from the list. */
publicationsCopy = list_delete(publicationsCopy, makeString(pubname));
ExecClearTuple(slot);
}
ExecDropSingleTupleTableSlot(slot);
walrcv_clear_result(res);
if (list_length(publicationsCopy))
{
/* Prepare the list of non-existent publication(s) for error message. */
StringInfo pubnames = makeStringInfo();
get_publications_str(publicationsCopy, pubnames, false);
ereport(WARNING,
errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg_plural("publication %s does not exist in the publisher",
"publications %s do not exist in the publisher",
list_length(publicationsCopy),
pubnames->data));
}
}
/*
* Auxiliary function to build a text array out of a list of String nodes.
*/
@ -555,6 +652,8 @@ CreateSubscription(ParseState *pstate, CreateSubscriptionStmt *stmt,
PG_TRY();
{
check_publications(wrconn, publications);
/*
* Set sync state based on if we were asked to do data copy or
* not.
@ -650,7 +749,8 @@ CreateSubscription(ParseState *pstate, CreateSubscriptionStmt *stmt,
}
static void
AlterSubscription_refresh(Subscription *sub, bool copy_data)
AlterSubscription_refresh(Subscription *sub, bool copy_data,
List *validate_publications)
{
char *err;
List *pubrel_names;
@ -681,6 +781,9 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data)
PG_TRY();
{
if (validate_publications)
check_publications(wrconn, validate_publications);
/* Get the list of relations from publisher. */
pubrel_names = fetch_table_list(wrconn, sub->publications);
pubrel_names = list_concat(pubrel_names,
@ -1048,7 +1151,8 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
/* Make sure refresh sees the new list of publications. */
sub->publications = stmt->publication;
AlterSubscription_refresh(sub, opts.copy_data);
AlterSubscription_refresh(sub, opts.copy_data,
stmt->publication);
}
break;
@ -1074,6 +1178,9 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
/* Refresh if user asked us to. */
if (opts.refresh)
{
/* We only need to validate user specified publications. */
List *validate_publications = (isadd) ? stmt->publication : NULL;
if (!sub->enabled)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@ -1096,7 +1203,8 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
/* Refresh the new list of publications. */
sub->publications = publist;
AlterSubscription_refresh(sub, opts.copy_data);
AlterSubscription_refresh(sub, opts.copy_data,
validate_publications);
}
break;
@ -1138,7 +1246,7 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION ... REFRESH");
AlterSubscription_refresh(sub, opts.copy_data);
AlterSubscription_refresh(sub, opts.copy_data, NULL);
break;
}
@ -1659,28 +1767,13 @@ fetch_table_list(WalReceiverConn *wrconn, List *publications)
StringInfoData cmd;
TupleTableSlot *slot;
Oid tableRow[2] = {TEXTOID, TEXTOID};
ListCell *lc;
bool first;
List *tablelist = NIL;
Assert(list_length(publications) > 0);
initStringInfo(&cmd);
appendStringInfoString(&cmd, "SELECT DISTINCT t.schemaname, t.tablename\n"
" FROM pg_catalog.pg_publication_tables t\n"
" WHERE t.pubname IN (");
first = true;
foreach(lc, publications)
{
char *pubname = strVal(lfirst(lc));
if (first)
first = false;
else
appendStringInfoString(&cmd, ", ");
appendStringInfoString(&cmd, quote_literal_cstr(pubname));
}
get_publications_str(publications, &cmd, true);
appendStringInfoChar(&cmd, ')');
res = walrcv_exec(wrconn, cmd.data, 2, tableRow);

37
src/test/subscription/t/007_ddl.pl
View File

@ -41,6 +41,43 @@ COMMIT;
pass "subscription disable and drop in same transaction did not hang";
# One of the specified publications exists.
my ($ret, $stdout, $stderr) = $node_subscriber->psql('postgres',
"CREATE SUBSCRIPTION mysub1 CONNECTION '$publisher_connstr' PUBLICATION mypub, non_existent_pub"
);
ok( $stderr =~
m/WARNING: publication "non_existent_pub" does not exist in the publisher/,
"Create subscription throws warning for non-existent publication");
$node_publisher->wait_for_catchup('mysub1');
# Also wait for initial table sync to finish.
my $synced_query =
"SELECT count(1) = 0 FROM pg_subscription_rel WHERE srsubstate NOT IN ('r', 's');";
$node_subscriber->poll_query_until('postgres', $synced_query)
or die "Timed out while waiting for subscriber to synchronize data";
# Also wait for initial table sync to finish.
$node_subscriber->poll_query_until('postgres', $synced_query)
or die "Timed out while waiting for subscriber to synchronize data";
# Specifying non-existent publication along with add publication.
($ret, $stdout, $stderr) = $node_subscriber->psql(
'postgres',
"ALTER SUBSCRIPTION mysub1 ADD PUBLICATION non_existent_pub1, non_existent_pub2"
);
ok( $stderr =~
m/WARNING: publications "non_existent_pub1", "non_existent_pub2" do not exist in the publisher/,
"Alter subscription add publication throws warning for non-existent publications");
# Specifying non-existent publication along with set publication.
($ret, $stdout, $stderr) = $node_subscriber->psql('postgres',
"ALTER SUBSCRIPTION mysub1 SET PUBLICATION non_existent_pub"
);
ok( $stderr =~
m/WARNING: publication "non_existent_pub" does not exist in the publisher/,
"Alter subscription set publication throws warning for non-existent publication");
$node_subscriber->stop;
$node_publisher->stop;