19 files changed, 195 insertions, 94 deletions
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index df0f15679f..d3de8934ee 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -431,8 +431,8 @@ CLOGShmemInit(void)
 /*
  * This func must be called ONCE on system install.  It creates
  * the initial CLOG segment.  (The CLOG directory is assumed to
- * have been created by the initdb shell script, and CLOGShmemInit
- * must have been called already.)
+ * have been created by initdb, and CLOGShmemInit must have been
+ * called already.)
  */
 void
 BootStrapCLOG(void)
diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 500335bd6f..555bb134f5 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,7 +21,6 @@
 #include "miscadmin.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
-#include "storage/predicate.h"
 #include "storage/proc.h"
 #include "utils/builtins.h"
 #include "utils/syscache.h"
@@ -162,10 +161,6 @@ GetNewTransactionId(bool isSubXact)
 	ExtendCLOG(xid);
 	ExtendSUBTRANS(xid);
 
-	/* If it's top level, the predicate locking system also needs to know. */
-	if (!isSubXact)
-		RegisterPredicateLockingXid(xid);
-
 	/*
 	 * Now advance the nextXid counter.  This must not happen until after we
 	 * have successfully completed ExtendCLOG() --- if that routine fails, we
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 8a4c4eccd7..2ca1c14549 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -455,6 +455,13 @@ AssignTransactionId(TransactionState s)
 		SubTransSetParent(s->transactionId, s->parent->transactionId, false);
 
 	/*
+	 * If it's a top-level transaction, the predicate locking system needs to
+	 * be told about it too.
+	 */
+	if (!isSubXact)
+		RegisterPredicateLockingXid(s->transactionId);
+
+	/*
 	 * Acquire lock on the transaction XID.  (We assume this cannot block.) We
 	 * have to ensure that the lock is assigned to the transaction's own
 	 * ResourceOwner.
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index b0e4c41d6f..e71090f71b 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6611,12 +6611,11 @@ StartupXLOG(void)
 	}
 
 	/*
-	 * If we launched a WAL receiver, it should be gone by now. It will trump
-	 * over the startup checkpoint and subsequent records if it's still alive,
-	 * so be extra sure that it's gone.
+	 * Kill WAL receiver, if it's still running, before we continue to write
+	 * the startup checkpoint record. It will trump over the checkpoint and
+	 * subsequent records if it's still alive when we start writing WAL.
 	 */
-	if (WalRcvInProgress())
-		elog(PANIC, "wal receiver still active");
+	ShutdownWalRcv();
 
 	/*
 	 * We don't need the latch anymore. It's not strictly necessary to disown
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index c623fb7e75..452a0ead44 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -2557,8 +2557,8 @@ CREATE VIEW _pg_foreign_tables AS
     WHERE w.oid = s.srvfdw
           AND u.oid = c.relowner
           AND (pg_has_role(c.relowner, 'USAGE')
-               OR has_table_privilege(c.oid, 'SELECT')
-               OR has_any_column_privilege(c.oid, 'SELECT'))
+               OR has_table_privilege(c.oid, 'SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, TRIGGER')
+               OR has_any_column_privilege(c.oid, 'SELECT, INSERT, UPDATE, REFERENCES'))
           AND n.oid = c.relnamespace
           AND c.oid = t.ftrelid
           AND c.relkind = 'f'
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 191ef543cd..dc0f6059b0 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -38,6 +38,7 @@
 #include "miscadmin.h"
 #include "optimizer/planner.h"
 #include "storage/bufmgr.h"
+#include "storage/lmgr.h"
 #include "storage/procarray.h"
 #include "storage/smgr.h"
 #include "utils/acl.h"
@@ -751,8 +752,24 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
 	isnull = (bool *) palloc(natts * sizeof(bool));
 
 	/*
+	 * If the OldHeap has a toast table, get lock on the toast table to keep
+	 * it from being vacuumed.  This is needed because autovacuum processes
+	 * toast tables independently of their main tables, with no lock on the
+	 * latter.  If an autovacuum were to start on the toast table after we
+	 * compute our OldestXmin below, it would use a later OldestXmin, and then
+	 * possibly remove as DEAD toast tuples belonging to main tuples we think
+	 * are only RECENTLY_DEAD.  Then we'd fail while trying to copy those
+	 * tuples.
+	 *
+	 * We don't need to open the toast relation here, just lock it.  The lock
+	 * will be held till end of transaction.
+	 */
+	if (OldHeap->rd_rel->reltoastrelid)
+		LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);
+
+	/*
 	 * We need to log the copied data in WAL iff WAL archiving/streaming is
-	 * enabled AND it's not a WAL-logged rel.
+	 * enabled AND it's a WAL-logged rel.
 	 */
 	use_wal = XLogIsNeeded() && RelationNeedsWAL(NewHeap);
 
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index ff84045d4f..b91e4a4bd2 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -183,10 +183,22 @@ DefineIndex(RangeVar *heapRelation,
 	/* Note: during bootstrap may see uncataloged relation */
 	if (rel->rd_rel->relkind != RELKIND_RELATION &&
 		rel->rd_rel->relkind != RELKIND_UNCATALOGED)
-		ereport(ERROR,
-				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is not a table",
-						heapRelation->relname)));
+	{
+		if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
+			/*
+			 * Custom error message for FOREIGN TABLE since the term is
+			 * close to a regular table and can confuse the user.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					 errmsg("cannot create index on foreign table \"%s\"",
+						 heapRelation->relname)));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					 errmsg("\"%s\" is not a table",
+							heapRelation->relname)));
+	}
 
 	/*
 	 * Don't try to CREATE INDEX on temp tables of other backends.
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 493bc86299..45eaa03fda 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -1065,6 +1065,11 @@ SS_process_ctes(PlannerInfo *root)
  * (Notionally, we replace the SubLink with a constant TRUE, then elide the
  * redundant constant from the qual.)
  *
+ * On success, the caller is also responsible for recursively applying
+ * pull_up_sublinks processing to the rarg and quals of the returned JoinExpr.
+ * (On failure, there is no need to do anything, since pull_up_sublinks will
+ * be applied when we recursively plan the sub-select.)
+ *
  * Side effects of a successful conversion include adding the SubLink's
  * subselect to the query's rangetable, so that it can be referenced in
  * the JoinExpr's rarg.
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index a70439cc67..5d163292c5 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -318,6 +318,7 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
 	{
 		SubLink    *sublink = (SubLink *) node;
 		JoinExpr   *j;
+		Relids		child_rels;
 
 		/* Is it a convertible ANY or EXISTS clause? */
 		if (sublink->subLinkType == ANY_SUBLINK)
@@ -326,7 +327,18 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
 											available_rels);
 			if (j)
 			{
-				/* Yes, insert the new join node into the join tree */
+				/* Yes; recursively process what we pulled up */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+				/* Pulled-up ANY/EXISTS quals can use those rels too */
+				child_rels = bms_add_members(child_rels, available_rels);
+				/* ... and any inserted joins get stacked onto j->rarg */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 child_rels,
+														 &j->rarg);
+				/* Now insert the new join node into the join tree */
 				j->larg = *jtlink;
 				*jtlink = (Node *) j;
 				/* and return NULL representing constant TRUE */
@@ -339,7 +351,18 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
 											   available_rels);
 			if (j)
 			{
-				/* Yes, insert the new join node into the join tree */
+				/* Yes; recursively process what we pulled up */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+				/* Pulled-up ANY/EXISTS quals can use those rels too */
+				child_rels = bms_add_members(child_rels, available_rels);
+				/* ... and any inserted joins get stacked onto j->rarg */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 child_rels,
+														 &j->rarg);
+				/* Now insert the new join node into the join tree */
 				j->larg = *jtlink;
 				*jtlink = (Node *) j;
 				/* and return NULL representing constant TRUE */
@@ -354,6 +377,7 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
 		/* If the immediate argument of NOT is EXISTS, try to convert */
 		SubLink    *sublink = (SubLink *) get_notclausearg((Expr *) node);
 		JoinExpr   *j;
+		Relids		child_rels;
 
 		if (sublink && IsA(sublink, SubLink))
 		{
@@ -363,7 +387,18 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
 												   available_rels);
 				if (j)
 				{
-					/* Yes, insert the new join node into the join tree */
+					/* Yes; recursively process what we pulled up */
+					j->rarg = pull_up_sublinks_jointree_recurse(root,
+																j->rarg,
+																&child_rels);
+					/* Pulled-up ANY/EXISTS quals can use those rels too */
+					child_rels = bms_add_members(child_rels, available_rels);
+					/* ... and any inserted joins get stacked onto j->rarg */
+					j->quals = pull_up_sublinks_qual_recurse(root,
+															 j->quals,
+															 child_rels,
+															 &j->rarg);
+					/* Now insert the new join node into the join tree */
 					j->larg = *jtlink;
 					*jtlink = (Node *) j;
 					/* and return NULL representing constant TRUE */
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 34ecd292cb..cc0d6f5557 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -597,7 +597,8 @@ static void SplitColQualList(List *qualList,
  * have any bad effects since obviously the keywords will still behave the
  * same as if they weren't keywords).  We need to do this for PARTITION,
  * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
- * so that they can follow a_expr without creating
+ * so that they can follow a_expr without creating postfix-operator problems;
+ * and for NULL so that it can follow b_expr in ColQualList without creating
  * postfix-operator problems.
  *
  * The frame_bound productions UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING
@@ -610,16 +611,16 @@ static void SplitColQualList(List *qualList,
  * blame any funny behavior of UNBOUNDED on the SQL standard, though.
  */
 %nonassoc	UNBOUNDED		/* ideally should have same precedence as IDENT */
-%nonassoc	IDENT PARTITION RANGE ROWS PRECEDING FOLLOWING
+%nonassoc	IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %nonassoc	NOTNULL
 %nonassoc	ISNULL
-%nonassoc	IS NULL_P TRUE_P FALSE_P UNKNOWN /* sets precedence for IS NULL, etc */
+%nonassoc	IS				/* sets precedence for IS NULL, etc */
 %left		'+' '-'
 %left		'*' '/' '%'
 %left		'^'
 /* Unary Operators */
-%left		AT ZONE			/* sets precedence for AT TIME ZONE */
+%left		AT				/* sets precedence for AT TIME ZONE */
 %left		COLLATE
 %right		UMINUS
 %left		'[' ']'
@@ -4125,9 +4126,7 @@ TriggerFuncArg:
 				}
 			| FCONST								{ $$ = makeString($1); }
 			| Sconst								{ $$ = makeString($1); }
-			| BCONST								{ $$ = makeString($1); }
-			| XCONST								{ $$ = makeString($1); }
-			| ColId									{ $$ = makeString($1); }
+			| ColLabel								{ $$ = makeString($1); }
 		;
 
 OptConstrFromTable:
@@ -9714,7 +9713,7 @@ a_expr:		c_expr									{ $$ = $1; }
 					n->location = @2;
 					$$ = (Node *) n;
 				}
-			| a_expr AT TIME ZONE a_expr
+			| a_expr AT TIME ZONE a_expr			%prec AT
 				{
 					FuncCall *n = makeNode(FuncCall);
 					n->funcname = SystemFuncName("timezone");
@@ -9896,7 +9895,7 @@ a_expr:		c_expr									{ $$ = $1; }
 			 *	a ISNULL
 			 *	a NOTNULL
 			 */
-			| a_expr IS NULL_P
+			| a_expr IS NULL_P							%prec IS
 				{
 					NullTest *n = makeNode(NullTest);
 					n->arg = (Expr *) $1;
@@ -9910,7 +9909,7 @@ a_expr:		c_expr									{ $$ = $1; }
 					n->nulltesttype = IS_NULL;
 					$$ = (Node *)n;
 				}
-			| a_expr IS NOT NULL_P
+			| a_expr IS NOT NULL_P						%prec IS
 				{
 					NullTest *n = makeNode(NullTest);
 					n->arg = (Expr *) $1;
@@ -9928,42 +9927,42 @@ a_expr:		c_expr									{ $$ = $1; }
 				{
 					$$ = (Node *)makeOverlaps($1, $3, @2, yyscanner);
 				}
-			| a_expr IS TRUE_P
+			| a_expr IS TRUE_P							%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
 					b->booltesttype = IS_TRUE;
 					$$ = (Node *)b;
 				}
-			| a_expr IS NOT TRUE_P
+			| a_expr IS NOT TRUE_P						%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
 					b->booltesttype = IS_NOT_TRUE;
 					$$ = (Node *)b;
 				}
-			| a_expr IS FALSE_P
+			| a_expr IS FALSE_P							%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
 					b->booltesttype = IS_FALSE;
 					$$ = (Node *)b;
 				}
-			| a_expr IS NOT FALSE_P
+			| a_expr IS NOT FALSE_P						%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
 					b->booltesttype = IS_NOT_FALSE;
 					$$ = (Node *)b;
 				}
-			| a_expr IS UNKNOWN
+			| a_expr IS UNKNOWN							%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
 					b->booltesttype = IS_UNKNOWN;
 					$$ = (Node *)b;
 				}
-			| a_expr IS NOT UNKNOWN
+			| a_expr IS NOT UNKNOWN						%prec IS
 				{
 					BooleanTest *b = makeNode(BooleanTest);
 					b->arg = (Expr *) $1;
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 9fa63a4e6e..fcc912f8e3 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -1108,6 +1108,7 @@ do_start_worker(void)
 	recentXid = ReadNewTransactionId();
 	xidForceLimit = recentXid - autovacuum_freeze_max_age;
 	/* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
+	/* this can cause the limit to go backwards by 3, but that's OK */
 	if (xidForceLimit < FirstNormalTransactionId)
 		xidForceLimit -= FirstNormalTransactionId;
 
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 48ff9cc151..3b3158efe5 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -2283,6 +2283,9 @@ PredicateLockTupleRowVersionLink(const Relation relation,
 	 * locks. Even if a serializable transaction starts concurrently,
 	 * we know it can't take any SIREAD locks on the modified tuple
 	 * because the caller is holding the associated buffer page lock.
+	 * Memory reordering isn't an issue; the memory barrier in the
+	 * LWLock acquisition guarantees that this read occurs while the
+	 * buffer page lock is held.
 	 */
 	if (!TransactionIdIsValid(PredXact->SxactGlobalXmin))
 		return;
diff --git a/src/backend/tsearch/spell.c b/src/backend/tsearch/spell.c
index 8c0eaa78a7..be1663cd88 100644
--- a/src/backend/tsearch/spell.c
+++ b/src/backend/tsearch/spell.c
@@ -75,7 +75,7 @@ NIFinishBuild(IspellDict *Conf)
  * doesn't need that.  The cpalloc and cpalloc0 macros are just documentation
  * to indicate which allocations actually require zeroing.
  */
-#define COMPACT_ALLOC_CHUNK 8192	/* must be > aset.c's allocChunkLimit */
+#define COMPACT_ALLOC_CHUNK 8192	/* amount to get from palloc at once */
 #define COMPACT_MAX_REQ		1024	/* must be < COMPACT_ALLOC_CHUNK */
 
 static void *
diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index db0a6487ac..0a12a9b2e1 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -3569,24 +3569,27 @@ DateTimeParseError(int dterr, const char *str, const char *datatype)
 static const datetkn *
 datebsearch(const char *key, const datetkn *base, int nel)
 {
-	const datetkn *last = base + nel - 1,
-			   *position;
-	int			result;
-
-	while (last >= base)
+	if (nel > 0)
 	{
-		position = base + ((last - base) >> 1);
-		result = key[0] - position->token[0];
-		if (result == 0)
+		const datetkn *last = base + nel - 1,
+				   *position;
+		int			result;
+
+		while (last >= base)
 		{
-			result = strncmp(key, position->token, TOKMAXLEN);
+			position = base + ((last - base) >> 1);
+			result = key[0] - position->token[0];
 			if (result == 0)
-				return position;
+			{
+				result = strncmp(key, position->token, TOKMAXLEN);
+				if (result == 0)
+					return position;
+			}
+			if (result < 0)
+				last = position - 1;
+			else
+				base = position + 1;
 		}
-		if (result < 0)
-			last = position - 1;
-		else
-			base = position + 1;
 	}
 	return NULL;
 }
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 1f6fba5f75..3ac3254afb 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -324,7 +324,7 @@ CheckMyDatabase(const char *name, bool am_superuser)
 					PGC_INTERNAL, PGC_S_OVERRIDE);
 	/* If we have no other source of client_encoding, use server encoding */
 	SetConfigOption("client_encoding", GetDatabaseEncodingName(),
-					PGC_BACKEND, PGC_S_DEFAULT);
+					PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
 
 	/* assign locale variables */
 	collate = NameStr(dbform->datcollate);
diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index 10ef12eb24..78907b939d 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -14,6 +14,7 @@
 #include <ctype.h>
 #include <unistd.h>
 
+#include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/guc.h"
@@ -109,7 +110,6 @@ ProcessConfigFile(GucContext context)
 				   *tail;
 	char	   *cvc = NULL;
 	struct config_string *cvc_struct;
-	const char *envvar;
 	int			i;
 
 	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
@@ -265,7 +265,7 @@ ProcessConfigFile(GucContext context)
 				stack->source = PGC_S_DEFAULT;
 		}
 
-		/* Now we can re-apply the wired-in default */
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
 		set_config_option(gconf->name, NULL, context, PGC_S_DEFAULT,
 						  GUC_ACTION_SET, true);
 		if (context == PGC_SIGHUP)
@@ -275,25 +275,28 @@ ProcessConfigFile(GucContext context)
 	}
 
 	/*
-	 * Restore any variables determined by environment variables.  This
-	 * is a no-op except in the case where one of these had been in the
-	 * config file and is now removed.  PGC_S_ENV_VAR will override the
-	 * wired-in default we just applied, but cannot override any other source.
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
 	 *
-	 * Keep this list in sync with InitializeGUCOptions()!
-	 * PGPORT can be ignored, because it cannot be changed without restart.
-	 * We assume rlimit hasn't changed, either.
+	 * In particular, we *must not* do this during the postmaster's
+	 * initial loading of the file, since the timezone functions in
+	 * particular should be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how
+	 * to set (or at least what to call to set) every variable that could
+	 * potentially have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source.
+	 * However, there's no time to redesign it for 9.1.
 	 */
-	envvar = getenv("PGDATESTYLE");
-	if (envvar != NULL)
-		set_config_option("datestyle", envvar, PGC_POSTMASTER,
-						  PGC_S_ENV_VAR, GUC_ACTION_SET, true);
-
-	envvar = getenv("PGCLIENTENCODING");
-	if (envvar != NULL)
-		set_config_option("client_encoding", envvar, PGC_POSTMASTER,
-						  PGC_S_ENV_VAR, GUC_ACTION_SET, true);
-
+	if (context == PGC_SIGHUP)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_initialize();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
 
 	/* If we got here all the options checked out okay, so apply them. */
 	for (item = head; item; item = item->next)
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 738e2152ba..92391eda2f 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -502,6 +502,7 @@ const char *const GucContext_Names[] =
 const char *const GucSource_Names[] =
 {
 	 /* PGC_S_DEFAULT */ "default",
+	 /* PGC_S_DYNAMIC_DEFAULT */ "default",
 	 /* PGC_S_ENV_VAR */ "environment variable",
 	 /* PGC_S_FILE */ "configuration file",
 	 /* PGC_S_ARGV */ "command line",
@@ -3269,6 +3270,7 @@ static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
 static int	guc_var_compare(const void *a, const void *b);
 static int	guc_name_compare(const char *namea, const char *nameb);
+static void InitializeGUCOptionsFromEnvironment(void);
 static void InitializeOneGUCOption(struct config_generic * gconf);
 static void push_old_value(struct config_generic * gconf, GucAction action);
 static void ReportGUCOption(struct config_generic * record);
@@ -3812,8 +3814,6 @@ void
 InitializeGUCOptions(void)
 {
 	int			i;
-	char	   *env;
-	long		stack_rlimit;
 
 	/*
 	 * Before log_line_prefix could possibly receive a nonempty setting, make
@@ -3852,9 +3852,25 @@ InitializeGUCOptions(void)
 
 	/*
 	 * For historical reasons, some GUC parameters can receive defaults from
-	 * environment variables.  Process those settings.	NB: if you add or
-	 * remove anything here, see also ProcessConfigFile().
+	 * environment variables.  Process those settings.
 	 */
+	InitializeGUCOptionsFromEnvironment();
+}
+
+/*
+ * Assign any GUC values that can come from the server's environment.
+ *
+ * This is called from InitializeGUCOptions, and also from ProcessConfigFile
+ * to deal with the possibility that a setting has been removed from
+ * postgresql.conf and should now get a value from the environment.
+ * (The latter is a kludge that should probably go away someday; if so,
+ * fold this back into InitializeGUCOptions.)
+ */
+static void
+InitializeGUCOptionsFromEnvironment(void)
+{
+	char	   *env;
+	long		stack_rlimit;
 
 	env = getenv("PGPORT");
 	if (env != NULL)
@@ -6334,6 +6350,7 @@ define_custom_variable(struct config_generic * variable)
 	switch (pHolder->gen.source)
 	{
 		case PGC_S_DEFAULT:
+		case PGC_S_DYNAMIC_DEFAULT:
 		case PGC_S_ENV_VAR:
 		case PGC_S_FILE:
 		case PGC_S_ARGV:
@@ -8420,15 +8437,13 @@ assign_timezone_abbreviations(const char *newval, void *extra)
  *
  * This is called after initial loading of postgresql.conf.  If no
  * timezone_abbreviations setting was found therein, select default.
+ * If a non-default value is already installed, nothing will happen.
  */
 void
 pg_timezone_abbrev_initialize(void)
 {
-	if (timezone_abbreviations_string == NULL)
-	{
-		SetConfigOption("timezone_abbreviations", "Default",
-						PGC_POSTMASTER, PGC_S_DEFAULT);
-	}
+	SetConfigOption("timezone_abbreviations", "Default",
+					PGC_POSTMASTER, PGC_S_DYNAMIC_DEFAULT);
 }
 
 static const char *
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index b8a1582eaa..655dad42c7 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -390,8 +390,7 @@
 #log_temp_files = -1			# log temporary files equal or larger
 					# than the specified size in kilobytes;
 					# -1 disables, 0 logs all temp files
-#log_timezone = unknown			# actually, defaults to TZ environment
-					# setting
+#log_timezone = '(defaults to server environment setting)'
 
 
 #------------------------------------------------------------------------------
@@ -471,8 +470,7 @@
 
 #datestyle = 'iso, mdy'
 #intervalstyle = 'postgres'
-#timezone = unknown			# actually, defaults to TZ environment
-					# setting
+#timezone = '(defaults to server environment setting)'
 #timezone_abbreviations = 'Default'     # Select the set of available time zone
 					# abbreviations.  Currently, there are
 					#   Default
diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
index e95dcb6b7c..140b0c74d9 100644
--- a/src/backend/utils/mmgr/aset.c
+++ b/src/backend/utils/mmgr/aset.c
@@ -89,7 +89,9 @@
  *
  * With the current parameters, request sizes up to 8K are treated as chunks,
  * larger requests go into dedicated blocks.  Change ALLOCSET_NUM_FREELISTS
- * to adjust the boundary point.
+ * to adjust the boundary point.  (But in contexts with small maxBlockSize,
+ * we may set the allocChunkLimit to less than 8K, so as to avoid space
+ * wastage.)
  *--------------------
  */
 
@@ -97,6 +99,8 @@
 #define ALLOCSET_NUM_FREELISTS	11
 #define ALLOC_CHUNK_LIMIT	(1 << (ALLOCSET_NUM_FREELISTS-1+ALLOC_MINBITS))
 /* Size of largest chunk that we use a fixed size for */
+#define ALLOC_CHUNK_FRACTION	4
+/* We allow chunks to be at most 1/4 of maxBlockSize (less overhead) */
 
 /*--------------------
  * The first block allocated for an allocset has size initBlockSize.
@@ -380,15 +384,20 @@ AllocSetContextCreate(MemoryContext parent,
 	/*
 	 * Compute the allocation chunk size limit for this context.  It can't be
 	 * more than ALLOC_CHUNK_LIMIT because of the fixed number of freelists.
-	 * If maxBlockSize is small then requests exceeding the maxBlockSize
-	 * should be treated as large chunks, too.	We have to have
-	 * allocChunkLimit a power of two, because the requested and
-	 * actually-allocated sizes of any chunk must be on the same side of the
-	 * limit, else we get confused about whether the chunk is "big".
+	 * If maxBlockSize is small then requests exceeding the maxBlockSize, or
+	 * even a significant fraction of it, should be treated as large chunks
+	 * too.  For the typical case of maxBlockSize a power of 2, the chunk size
+	 * limit will be at most 1/8th maxBlockSize, so that given a stream of
+	 * requests that are all the maximum chunk size we will waste at most
+	 * 1/8th of the allocated space.
+	 *
+	 * We have to have allocChunkLimit a power of two, because the requested
+	 * and actually-allocated sizes of any chunk must be on the same side of
+	 * the limit, else we get confused about whether the chunk is "big".
 	 */
 	context->allocChunkLimit = ALLOC_CHUNK_LIMIT;
-	while (context->allocChunkLimit >
-		   (Size) (maxBlockSize - ALLOC_BLOCKHDRSZ - ALLOC_CHUNKHDRSZ))
+	while ((Size) (context->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
+		   (Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))
 		context->allocChunkLimit >>= 1;
 
 	/*