Logical replication

- Add PUBLICATION catalogs and DDL
- Add SUBSCRIPTION catalog and DDL
- Define logical replication protocol and output plugin
- Add logical replication workers

From: Petr Jelinek <petr@2ndquadrant.com>
Reviewed-by: Steve Singer <steve@ssinger.info>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Erik Rijkers <er@xs4all.nl>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

1 files changed, 643 insertions, 0 deletions

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
new file mode 100644
index 00000000000..1448ee3beea
--- /dev/null
+++ b/src/backend/commands/subscriptioncmds.c
@@ -0,0 +1,643 @@
+/*-------------------------------------------------------------------------
+ *
+ * subscriptioncmds.c
+ *		subscription catalog manipulation functions
+ *
+ * Copyright (c) 2015, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		subscriptioncmds.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "miscadmin.h"
+
+#include "access/heapam.h"
+#include "access/htup_details.h"
+
+#include "catalog/indexing.h"
+#include "catalog/objectaccess.h"
+#include "catalog/objectaddress.h"
+#include "catalog/pg_type.h"
+#include "catalog/pg_subscription.h"
+
+#include "commands/defrem.h"
+#include "commands/event_trigger.h"
+#include "commands/subscriptioncmds.h"
+
+#include "replication/logicallauncher.h"
+#include "replication/origin.h"
+#include "replication/walreceiver.h"
+#include "replication/worker_internal.h"
+
+#include "storage/lmgr.h"
+
+#include "utils/builtins.h"
+#include "utils/memutils.h"
+#include "utils/syscache.h"
+
+/*
+ * Common option parsing function for CREATE and ALTER SUBSCRIPTION commands.
+ *
+ * Since not all options can be specified in both commands, this function
+ * will report an error on options if the target output pointer is NULL to
+ * accomodate that.
+ */
+static void
+parse_subscription_options(List *options, char **conninfo,
+						   List **publications, bool *enabled_given,
+						   bool *enabled, bool *create_slot, char **slot_name)
+{
+	ListCell   *lc;
+	bool		create_slot_given = false;
+
+	if (conninfo)
+		*conninfo = NULL;
+	if (publications)
+		*publications = NIL;
+	if (enabled)
+	{
+		*enabled_given = false;
+		*enabled = true;
+	}
+	if (create_slot)
+		*create_slot = true;
+	if (slot_name)
+		*slot_name = NULL;
+
+	/* Parse options */
+	foreach (lc, options)
+	{
+		DefElem    *defel = (DefElem *) lfirst(lc);
+
+		if (strcmp(defel->defname, "conninfo") == 0 && conninfo)
+		{
+			if (*conninfo)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*conninfo = defGetString(defel);
+		}
+		else if (strcmp(defel->defname, "publication") == 0 && publications)
+		{
+			if (*publications)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*publications = defGetStringList(defel);
+		}
+		else if (strcmp(defel->defname, "enabled") == 0 && enabled)
+		{
+			if (*enabled_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*enabled_given = true;
+			*enabled = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "disabled") == 0 && enabled)
+		{
+			if (*enabled_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*enabled_given = true;
+			*enabled = !defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "create slot") == 0 && create_slot)
+		{
+			if (create_slot_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			create_slot_given = true;
+			*create_slot = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "nocreate slot") == 0 && create_slot)
+		{
+			if (create_slot_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			create_slot_given = true;
+			*create_slot = !defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "slot name") == 0 && slot_name)
+		{
+			if (*slot_name)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*slot_name = defGetString(defel);
+		}
+		else
+			elog(ERROR, "unrecognized option: %s", defel->defname);
+	}
+}
+
+/*
+ * Auxiliary function to return a text array out of a list of String nodes.
+ */
+static Datum
+publicationListToArray(List *publist)
+{
+	ArrayType  *arr;
+	Datum	   *datums;
+	int			j = 0;
+	ListCell   *cell;
+	MemoryContext memcxt;
+	MemoryContext oldcxt;
+
+	/* Create memory context for temporary allocations. */
+	memcxt = AllocSetContextCreate(CurrentMemoryContext,
+								   "publicationListToArray to array",
+								   ALLOCSET_DEFAULT_MINSIZE,
+								   ALLOCSET_DEFAULT_INITSIZE,
+								   ALLOCSET_DEFAULT_MAXSIZE);
+	oldcxt = MemoryContextSwitchTo(memcxt);
+
+	datums = palloc(sizeof(text *) * list_length(publist));
+	foreach(cell, publist)
+	{
+		char	   *name = strVal(lfirst(cell));
+		ListCell   *pcell;
+
+		/* Check for duplicates. */
+		foreach(pcell, publist)
+		{
+			char	   *pname = strVal(lfirst(cell));
+
+			if (name == pname)
+				break;
+
+			if (strcmp(name, pname) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("publication name \"%s\" used more than once",
+								pname)));
+		}
+
+		datums[j++] = CStringGetTextDatum(name);
+	}
+
+	MemoryContextSwitchTo(oldcxt);
+
+	arr = construct_array(datums, list_length(publist),
+						  TEXTOID, -1, false, 'i');
+	MemoryContextDelete(memcxt);
+
+	return PointerGetDatum(arr);
+}
+
+/*
+ * Create new subscription.
+ */
+ObjectAddress
+CreateSubscription(CreateSubscriptionStmt *stmt)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	Oid			subid;
+	bool		nulls[Natts_pg_subscription];
+	Datum		values[Natts_pg_subscription];
+	HeapTuple	tup;
+	bool		enabled_given;
+	bool		enabled;
+	char	   *conninfo;
+	char	   *slotname;
+	char		originname[NAMEDATALEN];
+	bool		create_slot;
+	List	   *publications;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 (errmsg("must be superuser to create subscriptions"))));
+
+	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
+
+	/* Check if name is used */
+	subid = GetSysCacheOid2(SUBSCRIPTIONNAME, MyDatabaseId,
+							CStringGetDatum(stmt->subname));
+	if (OidIsValid(subid))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+				 errmsg("subscription \"%s\" already exists",
+						stmt->subname)));
+	}
+
+	/*
+	 * Parse and check options.
+	 * Connection and publication should not be specified here.
+	 */
+	parse_subscription_options(stmt->options, NULL, NULL,
+							   &enabled_given, &enabled,
+							   &create_slot, &slotname);
+	if (slotname == NULL)
+		slotname = stmt->subname;
+
+	conninfo = stmt->conninfo;
+	publications = stmt->publication;
+
+	/* Load the library providing us libpq calls. */
+	load_file("libpqwalreceiver", false);
+
+	/* Check the connection info string. */
+	walrcv_check_conninfo(conninfo);
+
+	/* Everything ok, form a new tuple. */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	values[Anum_pg_subscription_subdbid - 1] = ObjectIdGetDatum(MyDatabaseId);
+	values[Anum_pg_subscription_subname - 1] =
+		DirectFunctionCall1(namein, CStringGetDatum(stmt->subname));
+	values[Anum_pg_subscription_subowner - 1] = ObjectIdGetDatum(GetUserId());
+	values[Anum_pg_subscription_subenabled - 1] = BoolGetDatum(enabled);
+	values[Anum_pg_subscription_subconninfo - 1] =
+		CStringGetTextDatum(conninfo);
+	values[Anum_pg_subscription_subslotname - 1] =
+		DirectFunctionCall1(namein, CStringGetDatum(slotname));
+	values[Anum_pg_subscription_subpublications - 1] =
+		 publicationListToArray(publications);
+
+	tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
+
+	/* Insert tuple into catalog. */
+	subid = simple_heap_insert(rel, tup);
+	CatalogUpdateIndexes(rel, tup);
+	heap_freetuple(tup);
+
+	snprintf(originname, sizeof(originname), "pg_%u", subid);
+	replorigin_create(originname);
+
+	/*
+	 * If requested, create the replication slot on remote side for our
+	 * newly created subscription.
+	 */
+	if (create_slot)
+	{
+		XLogRecPtr			lsn;
+		char			   *err;
+		WalReceiverConn	   *wrconn;
+
+		/* Try to connect to the publisher. */
+		wrconn = walrcv_connect(conninfo, true, stmt->subname, &err);
+		if (!wrconn)
+			ereport(ERROR,
+					(errmsg("could not connect to the publisher: %s", err)));
+
+		walrcv_create_slot(wrconn, slotname, false, &lsn);
+		ereport(NOTICE,
+				(errmsg("created replication slot \"%s\" on publisher",
+						slotname)));
+
+		/* And we are done with the remote side. */
+		walrcv_disconnect(wrconn);
+	}
+
+	heap_close(rel, RowExclusiveLock);
+
+	ApplyLauncherWakeupAtCommit();
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+
+	InvokeObjectPostCreateHook(SubscriptionRelationId, subid, 0);
+
+	return myself;
+}
+
+/*
+ * Alter the existing subscription.
+ */
+ObjectAddress
+AlterSubscription(AlterSubscriptionStmt *stmt)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	bool		nulls[Natts_pg_subscription];
+	bool		replaces[Natts_pg_subscription];
+	Datum		values[Natts_pg_subscription];
+	HeapTuple	tup;
+	Oid			subid;
+	bool		enabled_given;
+	bool		enabled;
+	char	   *conninfo;
+	char	   *slot_name;
+	List	   *publications;
+
+	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
+
+	/* Fetch the existing tuple. */
+	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, MyDatabaseId,
+							  CStringGetDatum(stmt->subname));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription \"%s\" does not exist",
+						stmt->subname)));
+
+	/* must be owner */
+	if (!pg_subscription_ownercheck(HeapTupleGetOid(tup), GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_SUBSCRIPTION,
+					   stmt->subname);
+
+	subid = HeapTupleGetOid(tup);
+
+	/* Parse options. */
+	parse_subscription_options(stmt->options, &conninfo, &publications,
+							   &enabled_given, &enabled,
+							   NULL, &slot_name);
+
+	/* Form a new tuple. */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replaces, false, sizeof(replaces));
+
+	if (enabled_given)
+	{
+		values[Anum_pg_subscription_subenabled - 1] = BoolGetDatum(enabled);
+		replaces[Anum_pg_subscription_subenabled - 1] = true;
+	}
+	if (conninfo)
+	{
+		values[Anum_pg_subscription_subconninfo - 1] =
+			CStringGetTextDatum(conninfo);
+		replaces[Anum_pg_subscription_subconninfo - 1] = true;
+	}
+	if (slot_name)
+	{
+		values[Anum_pg_subscription_subslotname - 1] =
+			DirectFunctionCall1(namein, CStringGetDatum(slot_name));
+		replaces[Anum_pg_subscription_subslotname - 1] = true;
+	}
+	if (publications != NIL)
+	{
+		values[Anum_pg_subscription_subpublications - 1] =
+			 publicationListToArray(publications);
+		replaces[Anum_pg_subscription_subpublications - 1] = true;
+	}
+
+	tup = heap_modify_tuple(tup, RelationGetDescr(rel), values, nulls,
+							replaces);
+
+	/* Update the catalog. */
+	simple_heap_update(rel, &tup->t_self, tup);
+	CatalogUpdateIndexes(rel, tup);
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+
+	/* Cleanup. */
+	heap_freetuple(tup);
+	heap_close(rel, RowExclusiveLock);
+
+	InvokeObjectPostAlterHook(SubscriptionRelationId, subid, 0);
+
+	return myself;
+}
+
+/*
+ * Drop a subscription
+ */
+void
+DropSubscription(DropSubscriptionStmt *stmt)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	HeapTuple	tup;
+	Oid			subid;
+	Datum		datum;
+	bool		isnull;
+	char	   *subname;
+	char	   *conninfo;
+	char	   *slotname;
+	char		originname[NAMEDATALEN];
+	char	   *err = NULL;
+	RepOriginId	originid;
+	WalReceiverConn	   *wrconn = NULL;
+	StringInfoData		cmd;
+
+	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
+
+	tup = SearchSysCache2(SUBSCRIPTIONNAME, MyDatabaseId,
+						  CStringGetDatum(stmt->subname));
+
+	if (!HeapTupleIsValid(tup))
+	{
+		heap_close(rel, NoLock);
+
+		if (!stmt->missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("subscription \"%s\" does not exist",
+							stmt->subname)));
+		else
+			ereport(NOTICE,
+					(errmsg("subscription \"%s\" does not exist, skipping",
+							stmt->subname)));
+
+		return;
+	}
+
+	subid = HeapTupleGetOid(tup);
+
+	/* must be owner */
+	if (!pg_subscription_ownercheck(subid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_SUBSCRIPTION,
+					   stmt->subname);
+
+	/* DROP hook for the subscription being removed */
+	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
+
+	/*
+	 * Lock the subscription so noboby else can do anything with it
+	 * (including the replication workers).
+	 */
+	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+
+	/* Get subname */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subname, &isnull);
+	Assert(!isnull);
+	subname = pstrdup(NameStr(*DatumGetName(datum)));
+
+	/* Get conninfo */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subconninfo, &isnull);
+	Assert(!isnull);
+	conninfo = pstrdup(TextDatumGetCString(datum));
+
+	/* Get slotname */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subslotname, &isnull);
+	Assert(!isnull);
+	slotname = pstrdup(NameStr(*DatumGetName(datum)));
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+	EventTriggerSQLDropAddObject(&myself, true, true);
+
+	/* Remove the tuple from catalog. */
+	simple_heap_delete(rel, &tup->t_self);
+
+	ReleaseSysCache(tup);
+
+	/* Protect against launcher restarting the worker. */
+	LWLockAcquire(LogicalRepLauncherLock, LW_EXCLUSIVE);
+
+	/* Kill the apply worker so that the slot becomes accessible. */
+	logicalrep_worker_stop(subid);
+
+	/* Remove the origin tracking if exists. */
+	snprintf(originname, sizeof(originname), "pg_%u", subid);
+	originid = replorigin_by_name(originname, true);
+	if (originid != InvalidRepOriginId)
+		replorigin_drop(originid);
+
+	/* If the user asked to not drop the slot, we are done mow.*/
+	if (!stmt->drop_slot)
+	{
+		heap_close(rel, NoLock);
+		return;
+	}
+
+	/*
+	 * Otherwise drop the replication slot at the publisher node using
+	 * the replication connection.
+	 */
+	load_file("libpqwalreceiver", false);
+
+	initStringInfo(&cmd);
+	appendStringInfo(&cmd, "DROP_REPLICATION_SLOT \"%s\"", slotname);
+
+	wrconn = walrcv_connect(conninfo, true, subname, &err);
+	if (wrconn == NULL)
+		ereport(ERROR,
+				(errmsg("could not connect to publisher when attempting to "
+						"drop the replication slot \"%s\"", slotname),
+				 errdetail("The error was: %s", err)));
+
+	if (!walrcv_command(wrconn, cmd.data, &err))
+		ereport(ERROR,
+				(errmsg("count not drop the replication slot \"%s\" on publisher",
+						slotname),
+				 errdetail("The error was: %s", err)));
+	else
+		ereport(NOTICE,
+				(errmsg("dropped replication slot \"%s\" on publisher",
+						slotname)));
+
+	walrcv_disconnect(wrconn);
+
+	pfree(cmd.data);
+
+	heap_close(rel, NoLock);
+}
+
+/*
+ * Internal workhorse for changing a subscription owner
+ */
+static void
+AlterSubscriptionOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId)
+{
+	Form_pg_subscription form;
+
+	form = (Form_pg_subscription) GETSTRUCT(tup);
+
+	if (form->subowner == newOwnerId)
+		return;
+
+	if (!pg_subscription_ownercheck(HeapTupleGetOid(tup), GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_SUBSCRIPTION,
+					   NameStr(form->subname));
+
+	/* New owner must be a superuser */
+	if (!superuser_arg(newOwnerId))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+		  errmsg("permission denied to change owner of subscription \"%s\"",
+				 NameStr(form->subname)),
+			 errhint("The owner of an subscription must be a superuser.")));
+
+	form->subowner = newOwnerId;
+	simple_heap_update(rel, &tup->t_self, tup);
+	CatalogUpdateIndexes(rel, tup);
+
+	/* Update owner dependency reference */
+	changeDependencyOnOwner(SubscriptionRelationId,
+							HeapTupleGetOid(tup),
+							newOwnerId);
+
+	InvokeObjectPostAlterHook(SubscriptionRelationId,
+							  HeapTupleGetOid(tup), 0);
+}
+
+/*
+ * Change subscription owner -- by name
+ */
+ObjectAddress
+AlterSubscriptionOwner(const char *name, Oid newOwnerId)
+{
+	Oid			subid;
+	HeapTuple	tup;
+	Relation	rel;
+	ObjectAddress address;
+
+	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, MyDatabaseId,
+							  CStringGetDatum(name));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription \"%s\" does not exist", name)));
+
+	subid = HeapTupleGetOid(tup);
+
+	AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
+
+	ObjectAddressSet(address, SubscriptionRelationId, subid);
+
+	heap_freetuple(tup);
+
+	heap_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+/*
+ * Change subscription owner -- by OID
+ */
+void
+AlterSubscriptionOwner_oid(Oid subid, Oid newOwnerId)
+{
+	HeapTuple	tup;
+	Relation	rel;
+
+	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription with OID %u does not exist", subid)));
+
+	AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
+
+	heap_freetuple(tup);
+
+	heap_close(rel, RowExclusiveLock);
+}