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[PATCH v9 1/2] Let ALTER TABLE exec routines deal with the relation
47+ messages / 2 participants
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* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v3 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 511f015a86..2784fb11f9 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4393,7 +4395,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4402,10 +4403,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4417,7 +4418,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4443,11 +4448,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5545,6 +5551,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--J/dobhs11T7y2rNN
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v3-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v6 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b2457a6924..b990063d38 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4513,7 +4515,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4522,10 +4523,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4537,7 +4538,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4563,11 +4568,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5670,6 +5676,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--LZvS9be/3tNcYl/X
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v6-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v9 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3349bcfaa7..bf7fd6e8ae 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4569,7 +4571,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4578,10 +4579,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4593,7 +4594,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4619,11 +4624,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5730,6 +5736,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--IS0zKkzwUGydFO0o
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v9-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v8 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ffb1308a0c..8e753f1efd 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4512,7 +4514,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4521,10 +4522,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4536,7 +4537,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4562,11 +4567,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5669,6 +5675,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v8-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v8 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ffb1308a0c..8e753f1efd 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4512,7 +4514,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4521,10 +4522,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4536,7 +4537,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4562,11 +4567,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5669,6 +5675,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v8-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 993da56d43..a8528a3423 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -156,6 +156,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -353,7 +355,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4405,7 +4407,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4414,10 +4415,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4429,7 +4430,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4455,11 +4460,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5562,6 +5568,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--/04w6evG8XlLl3ft
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v5-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation
@ 2020-07-14 00:15 Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Alvaro Herrera @ 2020-07-14 00:15 UTC (permalink / raw)

This means that ATExecCmd relies on AlteredRelationInfo->rel instead of
keeping the relation as a local variable; this is useful if the
subcommand needs to modify the relation internally.  For example, a
subcommand that internally commits its transaction needs this.
---
 src/backend/commands/tablecmds.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ac53f79ada..07f4f562ee 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -157,6 +157,8 @@ typedef struct AlteredTableInfo
 	Oid			relid;			/* Relation to work on */
 	char		relkind;		/* Its relkind */
 	TupleDesc	oldDesc;		/* Pre-modification tuple descriptor */
+	/* Transiently set during Phase 2, normally set to NULL */
+	Relation	rel;
 	/* Information saved by Phase 1 for Phase 2: */
 	List	   *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
 	/* Information saved by Phases 1/2 for Phase 3: */
@@ -354,7 +356,7 @@ static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 					  AlterTableUtilityContext *context);
 static void ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 							  AlterTableUtilityContext *context);
-static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+static void ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 					  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 					  AlterTableUtilityContext *context);
 static AlterTableCmd *ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab,
@@ -4326,7 +4328,6 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 		{
 			AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
 			List	   *subcmds = tab->subcmds[pass];
-			Relation	rel;
 			ListCell   *lcmd;
 
 			if (subcmds == NIL)
@@ -4335,10 +4336,10 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			/*
 			 * Appropriate lock was obtained by phase 1, needn't get it again
 			 */
-			rel = relation_open(tab->relid, NoLock);
+			tab->rel = relation_open(tab->relid, NoLock);
 
 			foreach(lcmd, subcmds)
-				ATExecCmd(wqueue, tab, rel,
+				ATExecCmd(wqueue, tab,
 						  castNode(AlterTableCmd, lfirst(lcmd)),
 						  lockmode, pass, context);
 
@@ -4350,7 +4351,11 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
 			if (pass == AT_PASS_ALTER_TYPE)
 				ATPostAlterTypeCleanup(wqueue, tab, lockmode);
 
-			relation_close(rel, NoLock);
+			if (tab->rel)
+			{
+				relation_close(tab->rel, NoLock);
+				tab->rel = NULL;
+			}
 		}
 	}
 
@@ -4376,11 +4381,12 @@ ATRewriteCatalogs(List **wqueue, LOCKMODE lockmode,
  * ATExecCmd: dispatch a subcommand to appropriate execution routine
  */
 static void
-ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
+ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		  AlterTableCmd *cmd, LOCKMODE lockmode, int cur_pass,
 		  AlterTableUtilityContext *context)
 {
 	ObjectAddress address = InvalidObjectAddress;
+	Relation	rel = tab->rel;
 
 	switch (cmd->subtype)
 	{
@@ -5455,6 +5461,7 @@ ATGetQueueEntry(List **wqueue, Relation rel)
 	 */
 	tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
 	tab->relid = relid;
+	tab->rel = NULL;			/* set later */
 	tab->relkind = rel->rd_rel->relkind;
 	tab->oldDesc = CreateTupleDescCopyConstr(RelationGetDescr(rel));
 	tab->newrelpersistence = RELPERSISTENCE_PERMANENT;
-- 
2.20.1


--ikeVEW9yuYc//A+q
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 filename="v1-0002-ALTER-TABLE-.-DETACH-CONCURRENTLY.patch"



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

* Overhauling "Routine Vacuuming" docs, particularly its handling of freezing
@ 2023-04-24 21:57 Peter Geoghegan <[email protected]>
  0 siblings, 0 replies; 47+ messages in thread

From: Peter Geoghegan @ 2023-04-24 21:57 UTC (permalink / raw)
  To: PostgreSQL Hackers <[email protected]>

My work on page-level freezing for PostgreSQL 16 has some remaining
loose ends to tie up with the documentation. The "Routine Vacuuming"
section of the docs has no mention of page-level freezing. It also
doesn't mention the FPI optimization added by commit 1de58df4. This
isn't a small thing to leave out; I fully expect that the FPI
optimization will very significantly alter when and how VACUUM
freezes. The cadence will look quite a lot different.

It seemed almost impossible to fit in discussion of page-level
freezing to the existing structure. In part this is because the
existing documentation emphasizes the worst case scenario, rather than
talking about freezing as a maintenance task that affects physical
heap pages in roughly the same way as pruning does. There isn't a
clean separation of things that would allow me to just add a paragraph
about the FPI thing.

Obviously it's important that the system never enters xidStopLimit
mode -- not being able to allocate new XIDs is a huge problem. But it
seems unhelpful to define that as the only goal of freezing, or even
the main goal. To me this seems similar to defining the goal of
cleaning up bloat as avoiding completely running out of disk space;
while it may be "the single most important thing" in some general
sense, it isn't all that important in most individual cases. There are
many very bad things that will happen before that extreme worst case
is hit, which are far more likely to be the real source of pain.

There are also very big structural problems with "Routine Vacuuming",
that I also propose to do something about. Honestly, it's a huge mess
at this point. It's nobody's fault in particular; there has been
accretion after accretion added, over many years. It is time to
finally bite the bullet and do some serious restructuring. I'm hoping
that I don't get too much push back on this, because it's already very
difficult work.

Attached patch series shows what I consider to be a much better
overall structure. To make this convenient to take a quick look at, I
also attach a prebuilt version of routine-vacuuming.html (not the only
page that I've changed, but the most important set of changes by far).

This initial version is still quite lacking in overall polish, but I
believe that it gets the general structure right. That's what I'd like
to get feedback on right now: can I get agreement with me about the
general nature of the problem? Does this high level direction seem
like the right one?

The following list is a summary of the major changes that I propose:

1. Restructures the order of items to match the actual processing
order within VACUUM (and ANALYZE), rather than jumping from VACUUM to
ANALYZE and then back to VACUUM.

This flows a lot better, which helps with later items that deal with
freezing/wraparound.

2. Renamed "Preventing Transaction ID Wraparound Failures" to
"Freezing to manage the transaction ID space". Now we talk about
wraparound as a subtopic of freezing, not vice-versa. (This is a
complete rewrite, as described by later items in this list).

3. All of the stuff about modulo-2^32 arithmetic is moved to the
storage chapter, where we describe the heap tuple header format.

It seems crazy to me that the second sentence in our discussion of
wraparound/freezing is still:

"But since transaction IDs have limited size (32 bits) a cluster that
runs for a long time (more than 4 billion transactions) would suffer
transaction ID wraparound: the XID counter wraps around to zero, and
all of a sudden transactions that were in the past appear to be in the
future"

Here we start the whole discussion of wraparound (a particularly
delicate topic) by describing how VACUUM used to work 20 years ago,
before the invention of freezing. That was the last time that a
PostgreSQL cluster could run for 4 billion XIDs without freezing. The
invariant is that we activate xidStopLimit mode protections to avoid a
"distance" between any two unfrozen XIDs that exceeds about 2 billion
XIDs. So why on earth are we talking about 4 billion XIDs? This is the
most confusing, least useful way of describing freezing that I can
think of.

4. No more separate section for MultiXactID freezing -- that's
discussed as part of the discussion of page-level freezing.

Page-level freezing takes place without regard to the trigger
condition for freezing. So the new approach to freezing has a fixed
idea of what it means to freeze a given page (what physical
modifications it entails). This means that having a separate sect3
subsection for MultiXactIds now makes no sense (if it ever did).

5. The top-level list of maintenance tasks has a new addition: "To
truncate obsolescent transaction status information, when possible".

It makes a lot of sense to talk about this as something that happens
last (or last among those steps that take place during VACUUM). It's
far less important than avoiding xidStopLimit outages, obviously
(using some extra disk space is almost certainly the least of your
worries when you're near to xidStopLimit). The current documentation
seems to take precisely the opposite view, when it says the following:

"The sole disadvantage of increasing autovacuum_freeze_max_age (and
vacuum_freeze_table_age along with it) is that the pg_xact and
pg_commit_ts subdirectories of the database cluster will take more
space"

This sentence is dangerously bad advice. It is precisely backwards. At
the same time, we'd better say something about the need to truncate
pg_xact/clog here. Besides all this, the new section for this is a far
more accurate reflection of what's really going on: most individual
VACUUMs (even most aggressive VACUUMs) won't ever truncate
pg_xact/clog (or the other relevant SLRUs). Truncation only happens
after a VACUUM that advances the relfrozenxid of the table which
previously had the oldest relfrozenxid among all tables in the entire
cluster -- so we need to talk about it as an issue with the high
watermark storage for pg_xact.

6. Rename the whole "Routine Vacuuming" section to "Autovacuum
Maintenance Tasks".

This is what we should be emphasizing over manually run VACUUMs.
Besides, the current title just seems wrong -- we're talking about
ANALYZE just as much as VACUUM.

Thoughts?

-- 
Peter Geoghegan


Attachments:

  [text/html] routine-vacuuming.html (42.7K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/2-routine-vacuuming.html)
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>25.2. Autovacuum Maintenance Tasks</title><link rel="stylesheet" type="text/css" href="https://www.postgresql.org/media/css/docs-complete.css" /><link rev="made" href="[email protected]" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="autovacuum.html" title="25.1. The Autovacuum Daemon" /><link rel="next" href="routine-reindex.html" title="25.3. Routine Reindexing" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">25.2. Autovacuum Maintenance Tasks</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="autovacuum.html" title="25.1. The Autovacuum Daemon">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="maintenance.html" title="Chapter 25. Routine Database Maintenance Tasks">Up</a></td><th width="60%" align="center">Chapter 25. Routine Database Maintenance Tasks</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16devel Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="routine-reindex.html" title="25.3. Routine Reindexing">Next</a></td></tr></table><hr /></div><div class="sect1" id="ROUTINE-VACUUMING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">25.2. Autovacuum Maintenance Tasks <a href="#ROUTINE-VACUUMING" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY">25.2.1. Recovering Disk Space</a></span></dt><dt><span class="sect2"><a href="routine-vacuuming.html#FREEZING-XID-SPACE">25.2.2. Freezing to manage the transaction ID space</a></span></dt><dt><span class="sect2"><a href="routine-vacuuming.html#VACUUM-FOR-VISIBILITY-MAP">25.2.3. Updating the Visibility Map</a></span></dt><dt><span class="sect2"><a href="routine-vacuuming.html#VACUUM-TRUNCATE-PG-XACT">25.2.4. Truncating transaction status information</a></span></dt><dt><span class="sect2"><a href="routine-vacuuming.html#VACUUM-FOR-STATISTICS">25.2.5. Updating Planner Statistics</a></span></dt></dl></div><a id="id-1.6.12.11.2" class="indexterm"></a><p>
   <span class="productname">PostgreSQL</span> databases require periodic
   maintenance known as <em class="firstterm">vacuuming</em>, and require
   periodic updates to the statistics used by the
   <span class="productname">PostgreSQL</span> query planner.  These
   maintenance tasks are performed by the <a class="link" href="sql-vacuum.html" title="VACUUM"><code class="command">VACUUM</code></a> and <a class="link" href="sql-analyze.html" title="ANALYZE"><code class="command">ANALYZE</code></a> commands
   respectively.  For most installations, it is sufficient to let the
   <em class="firstterm">autovacuum daemon</em> determine when to perform
   these maintenance tasks (which is partly determined by configurable
   table-level thresholds; see <a class="xref" href="autovacuum.html" title="25.1. The Autovacuum Daemon">Section 25.1</a>).
  </p><p>
   The autovacuum daemon has to process each table on a regular basis
   for several reasons:

   </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">To recover or reuse disk space occupied by updated or deleted
     rows.</li><li class="listitem">To maintain the system's ability to allocated new
     transaction IDs (and new multixact IDs) through freezing.</li><li class="listitem">To update the visibility map, which speeds
     up <a class="link" href="indexes-index-only-scans.html" title="11.9. Index-Only Scans and Covering Indexes">index-only
     scans</a>, and helps the next <code class="command">VACUUM</code>
     operation avoid needlessly scanning pages that are already
     frozen</li><li class="listitem">To truncate obsolescent transaction status information,
     when possible</li><li class="listitem">To update data statistics used by the
     <span class="productname">PostgreSQL</span> query planner.</li></ol></div><p>

   Maintenance work within the scope of items 1, 2, 3, and 4 is
   performed by the <code class="command">VACUUM</code> command internally.
   Item 5 (maintenance of planner statistics) is handled by the
   <code class="command">ANALYZE</code> command internally.  Although this
   section presents information about autovacuum, there is no
   difference between manually-issued <code class="command">VACUUM</code> and
   <code class="command">ANALYZE</code> commands and those run by the autovacuum
   daemon (though there are autovacuum-specific variants of a small
   number of settings that control <code class="command">VACUUM</code>).
  </p><p>
   Autovacuum creates a substantial amount of I/O traffic, which can
   cause poor performance for other active sessions.  There are
   configuration parameters that can be adjusted to reduce the
   performance impact of background vacuuming.  See the
   autovacuum-specific cost delay settings described in
   <a class="xref" href="runtime-config-autovacuum.html" title="20.10. Automatic Vacuuming">Section 20.10</a>, and additional cost
   delay settings described in
   <a class="xref" href="runtime-config-resource.html#RUNTIME-CONFIG-RESOURCE-VACUUM-COST" title="20.4.4. Cost-based Vacuum Delay">Section 20.4.4</a>.
  </p><p>
   Some database administrators will want to supplement the daemon's
   activities with manually-managed <code class="command">VACUUM</code>
   commands, which typically are executed according to a schedule by
   <span class="application">cron</span> or <span class="application">Task
    Scheduler</span> scripts.  It can be useful to perform
   off-hours <code class="command">VACUUM</code> commands during periods where
   reduced load is expected.
  </p><div class="sect2" id="VACUUM-FOR-SPACE-RECOVERY"><div class="titlepage"><div><div><h3 class="title">25.2.1. Recovering Disk Space <a href="#VACUUM-FOR-SPACE-RECOVERY" class="id_link">#</a></h3></div></div></div><a id="id-1.6.12.11.7.2" class="indexterm"></a><p>
    In <span class="productname">PostgreSQL</span>, an
    <code class="command">UPDATE</code> or <code class="command">DELETE</code> of a row does not
    immediately remove the old version of the row.
    This approach is necessary to gain the benefits of multiversion
    concurrency control (<acronym class="acronym">MVCC</acronym>, see <a class="xref" href="mvcc.html" title="Chapter 13. Concurrency Control">Chapter 13</a>): the row version
    must not be deleted while it is still potentially visible to other
    transactions.  A deleted row version (whether from an
    <code class="command">UPDATE</code> or <code class="command">DELETE</code>) will
    usually cease to be of interest to any still running transaction
    shortly after the original deleting transaction commits.
   </p><p>
    The space dead tuples occupy must eventually be reclaimed for
    reuse by new rows, to avoid unbounded growth of disk space
    requirements.  Reclaiming space from dead rows is
    <code class="command">VACUUM</code>'s main responsibility.
   </p><p>
    The XID cutoff point that <code class="command">VACUUM</code> uses to
    determine whether or not a deleted tuple is safe to physically
    remove is reported under <code class="literal">removable cutoff</code> in
    the server log when autovacuum logging (controlled by <a class="xref" href="runtime-config-logging.html#GUC-LOG-AUTOVACUUM-MIN-DURATION">log_autovacuum_min_duration</a>) reports on a
    <code class="command">VACUUM</code> operation executed by autovacuum.
    Tuples that are not yet safe to remove are counted as
    <code class="literal">dead but not yet removable</code> tuples in the log
    report.  <code class="command">VACUUM</code> establishes its
    <code class="literal">removable cutoff</code> once, at the start of the
    operation.  Any older snapshot (or transaction that allocates an
    XID) that's still running when the cutoff is established may hold
    it back.
   </p><div class="tip"><h3 class="title">Tip</h3><p>
     It's important that no long running transactions ever be allowed
     to hold back every <code class="command">VACUUM</code> operation's cutoff
     for an extended period.  You may wish to monitor this.
    </p></div><div class="note"><h3 class="title">Note</h3><p>
     Tuples inserted by aborted transactions can be removed by
     <code class="command">VACUUM</code> immediately
    </p></div><p>
    <code class="command">VACUUM</code> will not return space to the operating
    system, except in the special case where a group of contiguous
    pages at the end of a table become entirely free and an exclusive
    table lock can be easily obtained.  This relation truncation
    behavior can be disabled in tables where the exclusive lock is
    disruptive by setting the table's <code class="varname">vacuum_truncate</code>
    storage parameter to <code class="literal">off</code>.
   </p><div class="tip"><h3 class="title">Tip</h3><p>
     If you have a table whose entire contents are deleted on a
     periodic basis, consider doing it with <a class="link" href="sql-truncate.html" title="TRUNCATE"><code class="command">TRUNCATE</code></a> rather
     than relying on <code class="command">VACUUM</code>.
     <code class="command">TRUNCATE</code> removes the entire contents of the
     table immediately, avoiding the need to set
     <code class="structfield">xmax</code> to the deleting transaction's XID.
     One disadvantage is that strict MVCC semantics are violated.
    </p></div><div class="tip"><h3 class="title">Tip</h3><p>
     <code class="command">VACUUM FULL</code> or <code class="command">CLUSTER</code> can
     be useful when dealing with extreme amounts of dead tuples.  It
     can reclaim more disk space, but runs much more slowly.  It
     rewrites an entire new copy of the table and rebuilds all indexes.
     This typically has much higher overhead than
     <code class="command">VACUUM</code>.  Generally, therefore, administrators
     should avoid using <code class="command">VACUUM FULL</code> except in the
     most extreme cases.
    </p></div><div class="note"><h3 class="title">Note</h3><p>
     Although <code class="command">VACUUM FULL</code> is technically an option
     of the <code class="command">VACUUM</code> command, <code class="command">VACUUM
      FULL</code> uses a completely different implementation.
     <code class="command">VACUUM FULL</code> is essentially a variant of
     <code class="command">CLUSTER</code>.  (The name <code class="command">VACUUM
      FULL</code> is historical; the original implementation was
     somewhat closer to standard <code class="command">VACUUM</code>.)
    </p></div><div class="warning"><h3 class="title">Warning</h3><p>
     <code class="command">TRUNCATE</code>, <code class="command">VACUUM FULL</code>, and
     <code class="command">CLUSTER</code> all require an <code class="literal">ACCESS
      EXCLUSIVE</code> lock, which can be highly disruptive
     (<code class="command">SELECT</code>, <code class="command">INSERT</code>,
     <code class="command">UPDATE</code>, and <code class="command">DELETE</code> commands
     will all be blocked).
    </p></div><div class="warning"><h3 class="title">Warning</h3><p>
     <code class="command">VACUUM FULL</code> (and <code class="command">CLUSTER</code>)
     temporarily uses extra disk space approximately equal to the size
     of the table, since the old copies of the table and indexes can't
     be released until the new ones are complete.
    </p></div></div><div class="sect2" id="FREEZING-XID-SPACE"><div class="titlepage"><div><div><h3 class="title">25.2.2. Freezing to manage the transaction ID space <a href="#FREEZING-XID-SPACE" class="id_link">#</a></h3></div></div></div><a id="id-1.6.12.11.8.2" class="indexterm"></a><a id="id-1.6.12.11.8.3" class="indexterm"></a><p>
    <span class="productname">PostgreSQL</span>'s <a class="link" href="mvcc-intro.html" title="13.1. Introduction">MVCC</a> transaction semantics depend on
    being able to compare <a class="glossterm" href="glossary.html#GLOSSARY-XID"><em class="glossterm"><a class="glossterm" href="glossary.html#GLOSSARY-XID" title="Transaction ID">transaction
     ID numbers (<acronym class="acronym">XID</acronym>)</a></em></a> to determine
    whether or not the row is visible to each query's MVCC snapshot
    (see <a class="link" href="storage-page-layout.html#INTERPRETING-XID-STAMPS" title="73.6.1.1. Interpreting XID stamps from tuple headers">
     interpreting XID stamps from tuple headers</a>).  But since
    on-disk storage of transaction IDs in heap pages uses a truncated
    32-bit representation to save space (rather than the full 64-bit
    representation), it is necessary to vacuum every table in every
    database <span class="emphasis"><em>at least</em></span> once every two billion
    transactions (though far more frequent vacuuming is typical).
   </p><p>
    <code class="command">VACUUM</code> marks pages as
    <span class="emphasis"><em>frozen</em></span>, indicating that all eligible rows on
    the page were inserted by a transaction that committed
    sufficiently far in the past that the effects of the inserting
    transaction are certain to be visible to all current and future
    transactions.  Frozen rows are treated as if the inserting
    transaction (the heap tuple's <code class="structfield">xmin</code> XID)
    committed <span class="quote">“<span class="quote">infinitely far in the past</span>”</span>, making the
    effects of the transaction visible to all current and future MVCC
    snapshots, forever.  Once frozen, pages are <span class="quote">“<span class="quote">self
     contained</span>”</span> in the sense that all of its rows can be read
    without ever having to consult externally stored transaction status
    metadata (for example, transaction commit status information from
    <code class="filename">pg_xact</code> is not required).
   </p><p>
    Without freezing, the system will eventually <a class="link" href="routine-vacuuming.html#XID-STOP-LIMIT" title="25.2.2.2. xidStopLimit mode">refuse to allocate new transaction
     IDs</a>, making <acronym class="acronym">DML</acronym> statements throw errors
    until such time as <code class="command">VACUUM</code> can restore the
    system's ability to allocate new transaction IDs.  The system is
    unable to recognize distances of more than about 2.1 billion
    transactions between any two unfrozen XIDs.  The only safe option
    that remains is to disallow allocating new XIDs until
    <code class="command">VACUUM</code> has performed the steps required to make
    sure that the <span class="quote">“<span class="quote">distance</span>”</span> invariant is never violated.
   </p><p>
    <a class="xref" href="runtime-config-client.html#GUC-VACUUM-FREEZE-MIN-AGE">vacuum_freeze_min_age</a> can be used to control
    when freezing takes place.  When <code class="command">VACUUM</code> scans a
    heap page containing even one XID that already attained an age
    exceeding this value, the page is frozen.  All tuples from the page
    are frozen, making the page suitable for long-term storage (their
    is no longer any possible need to interpret the contents of the
    page using external transaction status information).  Increasing
    this setting may avoid unnecessary work if the pages that would
    otherwise be frozen will soon be modified again, but decreasing
    this setting makes it more likely that some future
    <code class="command">VACUUM</code> operation will need to perform an
    excessive amount of <span class="quote">“<span class="quote">catch-up freezing</span>”</span>, all in one go.
   </p><a id="id-1.6.12.11.8.8" class="indexterm"></a><a id="id-1.6.12.11.8.9" class="indexterm"></a><p>
    <em class="firstterm">Multixact IDs</em> are used to support row
    locking by multiple transactions.  Since there is only limited
    space in a tuple header to store lock information, that
    information is encoded as a <span class="quote">“<span class="quote">multiple transaction
     ID</span>”</span>, or multixact ID for short, whenever there is more
    than one transaction concurrently locking a row.  Information
    about which transaction IDs are included in any particular
    multixact ID is stored separately, and only the multixact ID
    appears in the <code class="structfield">xmax</code> field in the tuple
    header.  Like transaction IDs, multixact IDs are implemented as a
    32-bit counter and corresponding storage.
    <span class="quote">“<span class="quote">Freezing</span>”</span> of multixact IDs is also required, though
    this actually means setting <code class="structfield">xmax</code> to
    <code class="literal">InvalidTransactionId</code>.
    
    (Actually, <span class="emphasis"><em>any</em></span> <code class="structfield">xmax</code>
    field is processed in the same way when its page is frozen,
    including <code class="structfield">xmax</code> fields that contain
    simple XIDs.)
   </p><p>
    <a class="xref" href="runtime-config-client.html#GUC-VACUUM-MULTIXACT-FREEZE-MIN-AGE">vacuum_multixact_freeze_min_age</a> can also
    influence which pages <code class="command">VACUUM</code> freezes.  Like
    <code class="varname">vacuum_freeze_min_age</code>, the setting triggers
    page-level freezing.  However,
    <code class="varname">vacuum_multixact_freeze_min_age</code> uses
    MultiXactIds (not XIDs) to measure <span class="quote">“<span class="quote">age</span>”</span>.
   </p><div class="note"><h3 class="title">Note</h3><p>
     In <span class="productname">PostgreSQL</span> versions before 16,
     freezing was triggered at the level of individual
     <code class="structfield">xmin</code> and
     <code class="structfield">xmax</code> fields.  The decision to freeze
     (or not freeze) is now made at the level of whole heap pages, at
     the point that they are scanned by <code class="command">VACUUM</code>.
    </p></div><p>
    In general, the major cost of freezing is the additional
    <acronym class="acronym">WAL</acronym> volume.  That's why
    <code class="command">VACUUM</code> doesn't just freeze every eligible tuple
    at the earliest opportunity: freezing will go to waste in cases
    where a recently frozen tuple soon goes on to be deleted anyway.
    Managing the added <acronym class="acronym">WAL</acronym> volume from freezing
    over time is an important consideration for
    <code class="command">VACUUM</code>.
   </p><p>
    <code class="command">VACUUM</code> also triggers freezing of pages in cases
    where it already proved necessary to write out an
    <acronym class="acronym">FPI</acronym> to the <acronym class="acronym">WAL</acronym> as torn page
    protection (as part of removing dead tuples).  The extra
    <acronym class="acronym">WAL</acronym> volume from proactive freezing is
    insignificant compared to the cost of the <acronym class="acronym">FPI</acronym>.
    It is very likely (though not quite certain) that the overall
    volume of <acronym class="acronym">WAL</acronym> will be lower in the long term
    with tables that have most freezing triggered by the
    <acronym class="acronym">FPI</acronym> mechanism, since (at least on average)
    future <code class="command">VACUUM</code>s shouldn't have to write a second
    <acronym class="acronym">FPI</acronym> out much later on, when freezing becomes
    strictly necessary.  The <acronym class="acronym">FPI</acronym> freezing mechanism
    is just an alternative trigger criteria for freezing all eligible
    tuples on the page.  In general, <code class="command">VACUUM</code> freezes
    pages without regard to the condition that triggered freezing.
    The physical modifications to the page (how tuples are processed)
    is decoupled from the mechanism that decides if those
    modifications should happen at all.
   </p><p>
    <code class="command">VACUUM</code> may not be able to freeze every tuple's
    <code class="structfield">xmin</code> in relatively rare cases.  The
    criteria that determines eligibility for freezing is exactly the
    same as the one that determines if a deleted tuple should be
    considered <code class="literal">removable</code> or merely <code class="literal">dead
     but not yet removable</code> (namely, the XID-based
    <code class="literal">removable cutoff</code>).
   </p><div class="sect3" id="AGGRESSIVE-STRATEGY"><div class="titlepage"><div><div><h4 class="title">25.2.2.1. <code class="command">VACUUM</code>'s aggressive strategy <a href="#AGGRESSIVE-STRATEGY" class="id_link">#</a></h4></div></div></div><p>
     To track the age of the oldest unfrozen XIDs in a database,
     <code class="command">VACUUM</code> stores XID statistics in the system
     tables <code class="structname">pg_class</code> and
     <code class="structname">pg_database</code>.  In particular, the
     <code class="structfield">relfrozenxid</code> column of a table's
     <code class="structname">pg_class</code> row contains the oldest
     remaining unfrozen XID at the end of the most recent
     <code class="command">VACUUM</code> that successfully advanced
     <code class="structfield">relfrozenxid</code>.  Similarly, the
     <code class="structfield">datfrozenxid</code> column of a database's
     <code class="structname">pg_database</code> row is a lower bound on the
     unfrozen XIDs appearing in that database — it is just the
     minimum of the per-table <code class="structfield">relfrozenxid</code>
     values within the database.
    </p><p>
     <code class="command">VACUUM</code> uses the <a class="link" href="storage-vm.html" title="73.4. Visibility Map">visibility map</a> to determine which
     pages of a table must be scanned.  Normally, it will skip pages
     that don't have any dead row versions even if those pages might
     still have row versions with old XID values.  Therefore, normal
     <code class="command">VACUUM</code>s usually won't freeze
     <span class="emphasis"><em>every</em></span> page with an old row version in the
     table.  Most individual tables will eventually need an
     <em class="firstterm">aggressive vacuum</em>, which will reliably
     freeze all pages with XID and MXID values older than
     <code class="varname">vacuum_freeze_min_age</code>, including those from
     all-visible but not all-frozen pages.  <a class="xref" href="runtime-config-client.html#GUC-VACUUM-FREEZE-TABLE-AGE">vacuum_freeze_table_age</a> controls when
     <code class="command">VACUUM</code> must use its aggressive strategy.
     Since the setting is applied against
     <code class="literal">age(relfrozenxid)</code>, settings like
     <code class="varname">vacuum_freeze_min_age</code> may influence the exact
     cadence of aggressive vacuuming.  Setting
     <code class="varname">vacuum_freeze_table_age</code> to 0 forces
     <code class="command">VACUUM</code> to always use its aggressive strategy.
    </p><div class="note"><h3 class="title">Note</h3><p>
      In practice most tables require periodic aggressive vacuuming.
      However, some individual non-aggressive
      <code class="command">VACUUM</code> operations may be able to advance
      <code class="structfield">relfrozenxid</code> and/or
      <code class="structfield">relminmxid</code>.  This is most common in
      small, frequently modified tables, where
      <code class="command">VACUUM</code> happens to scan all pages (or at least
      all pages not marked all-frozen) in the course of removing dead
      tuples.
     </p></div><p>
     The maximum time that a table can go unvacuumed is about two
     billion transactions. If it were to go unvacuumed for longer than
     that, the system will <a class="link" href="routine-vacuuming.html#XID-STOP-LIMIT" title="25.2.2.2. xidStopLimit mode">refuse to
      allocate new transaction IDs</a>, temporarily rendering the
     database read-only.  To ensure that this never happens,
     autovacuum is invoked on any table that might contain unfrozen
     rows with XIDs older than the age specified by the configuration
     parameter <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-FREEZE-MAX-AGE">autovacuum_freeze_max_age</a>.  (This
     will happen even if autovacuum is disabled.)
    </p><p>
     
     In practice all anti-wraparound autovacuums will use
     <code class="command">VACUUM</code>'s aggressive strategy.  This is assured
     because the effective value of
     <code class="varname">vacuum_freeze_table_age</code> is
     <span class="quote">“<span class="quote">clamped</span>”</span> to a value no greater than 95% of the
     current value of <code class="varname">autovacuum_freeze_max_age</code>.
     As a rule of thumb, <code class="command">vacuum_freeze_table_age</code>
     should be set to a value somewhat below
     <code class="varname">autovacuum_freeze_max_age</code>, leaving enough gap
     so that a regularly scheduled <code class="command">VACUUM</code> or an
     autovacuum triggered by inserts, updates and deletes is run in
     that window.  Anti-wraparound autovacuums can be avoided
     altogether in tables that reliably receive
     <span class="emphasis"><em>some</em></span> <code class="command">VACUUM</code>s that use the
     aggressive strategy.
    </p><div class="note"><h3 class="title">Note</h3><p>
      There is no fundamental difference between a
      <code class="command">VACUUM</code> run during anti-wraparound
      autovacuuming and a <code class="command">VACUUM</code> that happens to
      use the aggressive strategy (whether run by autovacuum or
      manually issued).
     </p></div><p>
     A convenient way to examine information about
     <code class="structfield">relfrozenxid</code> and
     <code class="structfield">relminmxid</code> is to execute queries such as:

</p><pre class="programlisting">
SELECT c.oid::regclass as table_name,
greatest(age(c.relfrozenxid),
         age(t.relfrozenxid)) as xid_age,
mxid_age(c.relminmxid)
FROM pg_class c
LEFT JOIN pg_class t ON c.reltoastrelid = t.oid
WHERE c.relkind IN ('r', 'm');

SELECT datname,
age(datfrozenxid) as xid_age,
mxid_age(datminmxid)
FROM pg_database;
</pre><p>

     The <code class="literal">age</code> column measures the number of
     transactions from the cutoff XID to the next unallocated
     transactions XID.  The <code class="literal">mxid_age</code> column
     measures the number of MultiXactIds from the cutoff MultiXactId
     to the next unallocated MultiXactId.
    </p><div class="tip"><h3 class="title">Tip</h3><p>
      When the <code class="command">VACUUM</code> command's
      <code class="literal">VERBOSE</code> parameter is specified,
      <code class="command">VACUUM</code> prints various statistics about the
      table.  This includes information about how
      <code class="structfield">relfrozenxid</code> and
      <code class="structfield">relminmxid</code> advanced, and the number
      of newly frozen pages.  The same details appear in the server
      log when autovacuum logging (controlled by <a class="xref" href="runtime-config-logging.html#GUC-LOG-AUTOVACUUM-MIN-DURATION">log_autovacuum_min_duration</a>) reports on a
      <code class="command">VACUUM</code> operation executed by autovacuum.
     </p></div></div><div class="sect3" id="XID-STOP-LIMIT"><div class="titlepage"><div><div><h4 class="title">25.2.2.2. <code class="literal">xidStopLimit</code> mode <a href="#XID-STOP-LIMIT" class="id_link">#</a></h4></div></div></div><p>
     If for some reason autovacuum utterly fails to advance any
     table's <code class="structfield">relfrozenxid</code> or
     <code class="structfield">relminmxid</code>, the system will begin to
     emit warning messages like this when the database's oldest XIDs
     reach forty million transactions from the wraparound point:

</p><pre class="programlisting">
WARNING:  database "mydb" must be vacuumed within 39985967 transactions
HINT:  To avoid a database shutdown, execute a database-wide VACUUM in that database.
</pre><p>

     (A manual <code class="command">VACUUM</code> should fix the problem, as suggested by the
     hint; but note that the <code class="command">VACUUM</code> must be performed by a
     superuser, else it will fail to process system catalogs and thus not
     be able to advance the database's <code class="structfield">datfrozenxid</code>.)
     If these warnings are ignored, the system will eventually refuse
     to start any new transactions.  This happens at the point that
     there are fewer than three million transactions left:

</p><pre class="programlisting">
ERROR:  database is not accepting commands to avoid wraparound data loss in database "mydb"
HINT:  Stop the postmaster and vacuum that database in single-user mode.
</pre><p>

     The three-million-transaction safety margin exists to let the
     administrator recover without data loss, by manually executing the
     required <code class="command">VACUUM</code> commands.  However, since the system will not
     execute commands once it has gone into the safety shutdown mode,
     the only way to do this is to stop the server and start the server in single-user
     mode to execute <code class="command">VACUUM</code>.  The shutdown mode is not enforced
     in single-user mode.  See the <a class="xref" href="app-postgres.html" title="postgres"><span class="refentrytitle"><span class="application">postgres</span></span></a> reference
     page for details about using single-user mode.
    </p><p>
     Anything that influences when and how
     <code class="structfield">relfrozenxid</code> and
     <code class="structfield">relminmxid</code> advance will also directly
     affect the high watermark storage overhead from storing a great
     deal of historical transaction status information.  The
     additional <a class="link" href="routine-vacuuming.html#VACUUM-TRUNCATE-PG-XACT" title="25.2.4. Truncating transaction status information">space
      overhead</a> is usually of fairly minimal concern.  It is
     noted as an additional downside of allowing the system to get
     close to <code class="literal">xidStopLimit</code> for the sake of
     completeness.
    </p><div class="note"><h3 class="title">Historical Note</h3><p>
      The term <span class="quote">“<span class="quote">wraparound</span>”</span> is inaccurate.  Also, there
      is no <span class="quote">“<span class="quote">data loss</span>”</span> here — the message is
      simply wrong.
     </p><p>
      XXX: We really need to fix the situation with single user mode
      to put things on a good footing.
     </p></div><p>
     In emergencies, <code class="command">VACUUM</code> will take extraordinary
     measures to avoid <code class="literal">xidStopLimit</code> mode.  A
     failsafe mechanism is triggered when thresholds controlled by
     <a class="xref" href="runtime-config-client.html#GUC-VACUUM-FAILSAFE-AGE">vacuum_failsafe_age</a> and <a class="xref" href="runtime-config-client.html#GUC-VACUUM-MULTIXACT-FAILSAFE-AGE">vacuum_multixact_failsafe_age</a> are reached.  The
     failsafe prioritizes advancing
     <code class="structfield">relfrozenxid</code> and/or
     <code class="structfield">relminmxid</code> as quickly as possible.
     Once the failsafe triggers, <code class="command">VACUUM</code> bypasses
     all remaining non-essential maintenance tasks, and stops applying
     any cost-based delay that was in effect.  Any <a class="glossterm" href="glossary.html#GLOSSARY-BUFFER-ACCESS-STRATEGY"><em class="glossterm"><a class="glossterm" href="glossary.html#GLOSSARY-BUFFER-ACCESS-STRATEGY" title="Buffer Access Strategy">Buffer Access
     Strategy</a></em></a> in use will also be disabled.
    </p></div></div><div class="sect2" id="VACUUM-FOR-VISIBILITY-MAP"><div class="titlepage"><div><div><h3 class="title">25.2.3. Updating the Visibility Map <a href="#VACUUM-FOR-VISIBILITY-MAP" class="id_link">#</a></h3></div></div></div><p>
    Vacuum maintains a <a class="link" href="storage-vm.html" title="73.4. Visibility Map">visibility
     map</a> for each table to keep track of which pages contain
    only tuples that are known to be visible to all active
    transactions (and all future transactions, until the page is again
    modified).  This has two purposes.  First, vacuum itself can skip
    such pages on the next run, since there is nothing to clean up.
    Even <code class="command">VACUUM</code>s that use the <a class="link" href="routine-vacuuming.html#AGGRESSIVE-STRATEGY" title="25.2.2.1. VACUUM's aggressive strategy">aggressive strategy</a> can skip
    pages that are both all-visible and all-frozen (the visibility map
    keeps track of which pages are all-frozen separately).
   </p><p>
    Second, it allows <span class="productname">PostgreSQL</span> to answer
    some queries using only the index, without reference to the
    underlying table.  Since <span class="productname">PostgreSQL</span>
    indexes don't contain tuple visibility information, a normal index
    scan fetches the heap tuple for each matching index entry, to
    check whether it should be seen by the current transaction.  An
    <a class="link" href="indexes-index-only-scans.html" title="11.9. Index-Only Scans and Covering Indexes"><em class="firstterm">index-only
      scan</em></a>, on the other hand, checks the
    visibility map first.  If it's known that all tuples on the page
    are visible, the heap fetch can be skipped.  This is most useful
    on large data sets where the visibility map can prevent disk
    accesses.  The visibility map is vastly smaller than the heap, so
    it can easily be cached even when the heap is very large.
   </p></div><div class="sect2" id="VACUUM-TRUNCATE-PG-XACT"><div class="titlepage"><div><div><h3 class="title">25.2.4. Truncating transaction status information <a href="#VACUUM-TRUNCATE-PG-XACT" class="id_link">#</a></h3></div></div></div><p>
    As noted in <a class="xref" href="routine-vacuuming.html#XID-STOP-LIMIT" title="25.2.2.2. xidStopLimit mode">Section 25.2.2.2</a>, anything that
    influences when and how <code class="structfield">relfrozenxid</code> and
    <code class="structfield">relminmxid</code> advance will also directly
    affect the high watermark storage overhead needed to store
    historical transaction status information.  For example,
    increasing <code class="varname">autovacuum_freeze_max_age</code> (and
    <code class="varname">vacuum_freeze_table_age</code> along with it) will
    make the <code class="filename">pg_xact</code> and
    <code class="filename">pg_commit_ts</code> subdirectories of the database
    cluster take more space, because they store the commit status and
    (if <code class="varname">track_commit_timestamp</code> is enabled)
    timestamp of all transactions back to the
    <code class="varname">datfrozenxid</code> horizon (the earliest
    <code class="varname">datfrozenxid</code> in the entire cluster).
   </p><p>
    The commit status uses two bits per transaction.  The default
    <code class="varname">autovacuum_freeze_max_age</code> setting of 200
    million transactions translates to about 50MB of
    <code class="filename">pg_xact</code> storage.  When
    <code class="varname">track_commit_timestamp</code> is enabled, about 2GB of
    <code class="filename">pg_commit_ts</code> storage will also be required.
   </p><p>
    MultiXactId status information is implemented as two separate
    <acronym class="acronym">SLRU</acronym> storage areas:
    <code class="filename">pg_multixact/members</code>, and
    <code class="filename">pg_multixact/offsets</code>.  There is no simple
    formula to determine the storage overhead per MultiXactId, since
    MultiXactIds have a variable number of member XIDs.
   </p><p>
    Truncating of transaction status information is only possible at
    the end of <code class="command">VACUUM</code>s that advance
    <code class="structfield">relfrozenxid</code> (in the case of
    <code class="filename">pg_xact</code> and
    <code class="filename">pg_commit_ts</code>) or
    <code class="structfield">relminmxid</code> (in the case of
    (<code class="filename">pg_multixact/members</code> and
    <code class="filename">pg_multixact/offsets</code>) of whatever table
    happened to have the oldest value in the cluster when the
    <code class="command">VACUUM</code> began.  This typically happens very
    infrequently, often during <a class="link" href="routine-vacuuming.html#AGGRESSIVE-STRATEGY" title="25.2.2.1. VACUUM's aggressive strategy">aggressive strategy</a>
    <code class="command">VACUUM</code>s of one of the database's largest
    tables.
   </p></div><div class="sect2" id="VACUUM-FOR-STATISTICS"><div class="titlepage"><div><div><h3 class="title">25.2.5. Updating Planner Statistics <a href="#VACUUM-FOR-STATISTICS" class="id_link">#</a></h3></div></div></div><a id="id-1.6.12.11.11.2" class="indexterm"></a><a id="id-1.6.12.11.11.3" class="indexterm"></a><p>
    The <span class="productname">PostgreSQL</span> query planner relies on
    statistical information about the contents of tables in order to
    generate good plans for queries.  These statistics are gathered by
    the <a class="link" href="sql-analyze.html" title="ANALYZE"><code class="command">ANALYZE</code></a> command,
    which can be invoked by itself or
    as an optional step in <code class="command">VACUUM</code>.  It is important to have
    reasonably accurate statistics, otherwise poor choices of plans might
    degrade database performance.
   </p><p>
    The autovacuum daemon, if enabled, will automatically issue
    <code class="command">ANALYZE</code> commands whenever the content of a table has
    changed sufficiently.  However, administrators might prefer to rely
    on manually-scheduled <code class="command">ANALYZE</code> operations, particularly
    if it is known that update activity on a table will not affect the
    statistics of <span class="quote">“<span class="quote">interesting</span>”</span> columns.  The daemon schedules
    <code class="command">ANALYZE</code> strictly as a function of the number of rows
    inserted or updated; it has no knowledge of whether that will lead
    to meaningful statistical changes.
   </p><p>
    Tuples changed in partitions and inheritance children do not trigger
    analyze on the parent table.  If the parent table is empty or rarely
    changed, it may never be processed by autovacuum, and the statistics for
    the inheritance tree as a whole won't be collected. It is necessary to
    run <code class="command">ANALYZE</code> on the parent table manually in order to
    keep the statistics up to date.
   </p><p>
    As with vacuuming for space recovery, frequent updates of statistics
    are more useful for heavily-updated tables than for seldom-updated
    ones. But even for a heavily-updated table, there might be no need for
    statistics updates if the statistical distribution of the data is
    not changing much. A simple rule of thumb is to think about how much
    the minimum and maximum values of the columns in the table change.
    For example, a <code class="type">timestamp</code> column that contains the time
    of row update will have a constantly-increasing maximum value as
    rows are added and updated; such a column will probably need more
    frequent statistics updates than, say, a column containing URLs for
    pages accessed on a website. The URL column might receive changes just
    as often, but the statistical distribution of its values probably
    changes relatively slowly.
   </p><p>
    It is possible to run <code class="command">ANALYZE</code> on specific tables and even
    just specific columns of a table, so the flexibility exists to update some
    statistics more frequently than others if your application requires it.
    In practice, however, it is usually best to just analyze the entire
    database, because it is a fast operation.  <code class="command">ANALYZE</code> uses a
    statistically random sampling of the rows of a table rather than reading
    every single row.
   </p><div class="tip"><h3 class="title">Tip</h3><p>
     Although per-column tweaking of <code class="command">ANALYZE</code> frequency might not be
     very productive, you might find it worthwhile to do per-column
     adjustment of the level of detail of the statistics collected by
     <code class="command">ANALYZE</code>.  Columns that are heavily used in <code class="literal">WHERE</code>
     clauses and have highly irregular data distributions might require a
     finer-grain data histogram than other columns.  See <code class="command">ALTER TABLE
      SET STATISTICS</code>, or change the database-wide default using the <a class="xref" href="runtime-config-query.html#GUC-DEFAULT-STATISTICS-TARGET">default_statistics_target</a> configuration parameter.
    </p><p>
     Also, by default there is limited information available about
     the selectivity of functions.  However, if you create a statistics
     object or an expression
     index that uses a function call, useful statistics will be
     gathered about the function, which can greatly improve query
     plans that use the expression index.
    </p></div><div class="tip"><h3 class="title">Tip</h3><p>
     The autovacuum daemon does not issue <code class="command">ANALYZE</code> commands for
     foreign tables, since it has no means of determining how often that
     might be useful.  If your queries require statistics on foreign tables
     for proper planning, it's a good idea to run manually-managed
     <code class="command">ANALYZE</code> commands on those tables on a suitable schedule.
    </p></div><div class="tip"><h3 class="title">Tip</h3><p>
     The autovacuum daemon does not issue <code class="command">ANALYZE</code> commands
     for partitioned tables.  Inheritance parents will only be analyzed if the
     parent itself is changed - changes to child tables do not trigger
     autoanalyze on the parent table.  If your queries require statistics on
     parent tables for proper planning, it is necessary to periodically run
     a manual <code class="command">ANALYZE</code> on those tables to keep the statistics
     up to date.
    </p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="autovacuum.html" title="25.1. The Autovacuum Daemon">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="maintenance.html" title="Chapter 25. Routine Database Maintenance Tasks">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="routine-reindex.html" title="25.3. Routine Reindexing">Next</a></td></tr><tr><td width="40%" align="left" valign="top">25.1. The Autovacuum Daemon </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16devel Documentation">Home</a></td><td width="40%" align="right" valign="top"> 25.3. Routine Reindexing</td></tr></table></div></body></html>

  [application/octet-stream] v1-0009-Overhaul-Recovering-Disk-Space-vacuuming-docs.patch (10.7K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/3-v1-0009-Overhaul-Recovering-Disk-Space-vacuuming-docs.patch)
  download | inline diff:
From bdefa0e5bf8616e9d9afa18ef44e38bd5f77a84e Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 12:33:42 -0700
Subject: [PATCH v1 9/9] Overhaul "Recovering Disk Space" vacuuming docs.

Say a lot more about the possible impact of long-running transactions on
VACUUM.  Remove all talk of administrators getting by without
autovacuum; at most administrators might want to schedule manual VACUUM
operations to supplement autovacuum (this documentation was written at a
time when the visibility map didn't exist, even in its most basic form).

Also describe VACUUM FULL as an entirely different kind of operation to
conventional lazy vacuum.
---
 doc/src/sgml/maintenance.sgml | 173 ++++++++++++++++++----------------
 1 file changed, 93 insertions(+), 80 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 169c6f41a..bb21474e1 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -342,100 +342,113 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
     This approach is necessary to gain the benefits of multiversion
     concurrency control (<acronym>MVCC</acronym>, see <xref linkend="mvcc"/>): the row version
     must not be deleted while it is still potentially visible to other
-    transactions. But eventually, an outdated or deleted row version is no
-    longer of interest to any transaction. The space it occupies must then be
-    reclaimed for reuse by new rows, to avoid unbounded growth of disk
-    space requirements. This is done by running <command>VACUUM</command>.
+    transactions.  A deleted row version (whether from an
+    <command>UPDATE</command> or <command>DELETE</command>) will
+    usually cease to be of interest to any still running transaction
+    shortly after the original deleting transaction commits.
    </para>
 
    <para>
-    The standard form of <command>VACUUM</command> removes dead row
-    versions in tables and indexes and marks the space available for
-    future reuse.  However, it will not return the space to the operating
-    system, except in the special case where one or more pages at the
-    end of a table become entirely free and an exclusive table lock can be
-    easily obtained.  In contrast, <command>VACUUM FULL</command> actively compacts
-    tables by writing a complete new version of the table file with no dead
-    space.  This minimizes the size of the table, but can take a long time.
-    It also requires extra disk space for the new copy of the table, until
-    the operation completes.
+    The space dead tuples occupy must eventually be reclaimed for
+    reuse by new rows, to avoid unbounded growth of disk space
+    requirements.  Reclaiming space from dead rows is
+    <command>VACUUM</command>'s main responsibility.
    </para>
 
    <para>
-    The usual goal of routine vacuuming is to do standard <command>VACUUM</command>s
-    often enough to avoid needing <command>VACUUM FULL</command>.  The
-    autovacuum daemon attempts to work this way, and in fact will
-    never issue <command>VACUUM FULL</command>.  In this approach, the idea
-    is not to keep tables at their minimum size, but to maintain steady-state
-    usage of disk space: each table occupies space equivalent to its
-    minimum size plus however much space gets used up between vacuum runs.
-    Although <command>VACUUM FULL</command> can be used to shrink a table back
-    to its minimum size and return the disk space to the operating system,
-    there is not much point in this if the table will just grow again in the
-    future.  Thus, moderately-frequent standard <command>VACUUM</command> runs are a
-    better approach than infrequent <command>VACUUM FULL</command> runs for
-    maintaining heavily-updated tables.
-   </para>
-
-   <para>
-    Some administrators prefer to schedule vacuuming themselves, for example
-    doing all the work at night when load is low.
-    The difficulty with doing vacuuming according to a fixed schedule
-    is that if a table has an unexpected spike in update activity, it may
-    get bloated to the point that <command>VACUUM FULL</command> is really necessary
-    to reclaim space.  Using the autovacuum daemon alleviates this problem,
-    since the daemon schedules vacuuming dynamically in response to update
-    activity.  It is unwise to disable the daemon completely unless you
-    have an extremely predictable workload.  One possible compromise is
-    to set the daemon's parameters so that it will only react to unusually
-    heavy update activity, thus keeping things from getting out of hand,
-    while scheduled <command>VACUUM</command>s are expected to do the bulk of the
-    work when the load is typical.
-   </para>
-
-   <para>
-    For those not using autovacuum, a typical approach is to schedule a
-    database-wide <command>VACUUM</command> once a day during a low-usage period,
-    supplemented by more frequent vacuuming of heavily-updated tables as
-    necessary. (Some installations with extremely high update rates vacuum
-    their busiest tables as often as once every few minutes.) If you have
-    multiple databases in a cluster, don't forget to
-    <command>VACUUM</command> each one; the program <xref
-    linkend="app-vacuumdb"/> might be helpful.
+    The XID cutoff point that <command>VACUUM</command> uses to
+    determine whether or not a deleted tuple is safe to physically
+    remove is reported under <literal>removable cutoff</literal> in
+    the server log when autovacuum logging (controlled by <xref
+     linkend="guc-log-autovacuum-min-duration"/>) reports on a
+    <command>VACUUM</command> operation executed by autovacuum.
+    Tuples that are not yet safe to remove are counted as
+    <literal>dead but not yet removable</literal> tuples in the log
+    report.  <command>VACUUM</command> establishes its
+    <literal>removable cutoff</literal> once, at the start of the
+    operation.  Any older snapshot (or transaction that allocates an
+    XID) that's still running when the cutoff is established may hold
+    it back.
    </para>
 
    <tip>
-   <para>
-    Plain <command>VACUUM</command> may not be satisfactory when
-    a table contains large numbers of dead row versions as a result of
-    massive update or delete activity.  If you have such a table and
-    you need to reclaim the excess disk space it occupies, you will need
-    to use <command>VACUUM FULL</command>, or alternatively
-    <link linkend="sql-cluster"><command>CLUSTER</command></link>
-    or one of the table-rewriting variants of
-    <link linkend="sql-altertable"><command>ALTER TABLE</command></link>.
-    These commands rewrite an entire new copy of the table and build
-    new indexes for it.  All these options require an
-    <literal>ACCESS EXCLUSIVE</literal> lock.  Note that
-    they also temporarily use extra disk space approximately equal to the size
-    of the table, since the old copies of the table and indexes can't be
-    released until the new ones are complete.
-   </para>
+    <para>
+     It's important that no long running transactions ever be allowed
+     to hold back every <command>VACUUM</command> operation's cutoff
+     for an extended period.  You may wish to monitor this.
+    </para>
    </tip>
 
-   <tip>
+   <note>
+    <para>
+     Tuples inserted by aborted transactions can be removed by
+     <command>VACUUM</command> immediately
+    </para>
+   </note>
+
    <para>
-    If you have a table whose entire contents are deleted on a periodic
-    basis, consider doing it with
-    <link linkend="sql-truncate"><command>TRUNCATE</command></link> rather
-    than using <command>DELETE</command> followed by
-    <command>VACUUM</command>. <command>TRUNCATE</command> removes the
-    entire content of the table immediately, without requiring a
-    subsequent <command>VACUUM</command> or <command>VACUUM
-    FULL</command> to reclaim the now-unused disk space.
-    The disadvantage is that strict MVCC semantics are violated.
+    <command>VACUUM</command> will not return space to the operating
+    system, except in the special case where a group of contiguous
+    pages at the end of a table become entirely free and an exclusive
+    table lock can be easily obtained.  This relation truncation
+    behavior can be disabled in tables where the exclusive lock is
+    disruptive by setting the table's <varname>vacuum_truncate</varname>
+    storage parameter to <literal>off</literal>.
    </para>
+
+   <tip>
+    <para>
+     If you have a table whose entire contents are deleted on a
+     periodic basis, consider doing it with <link
+      linkend="sql-truncate"><command>TRUNCATE</command></link> rather
+     than relying on <command>VACUUM</command>.
+     <command>TRUNCATE</command> removes the entire contents of the
+     table immediately, avoiding the need to set
+     <structfield>xmax</structfield> to the deleting transaction's XID.
+     One disadvantage is that strict MVCC semantics are violated.
+    </para>
    </tip>
+   <tip>
+    <para>
+     <command>VACUUM FULL</command> or <command>CLUSTER</command> can
+     be useful when dealing with extreme amounts of dead tuples.  It
+     can reclaim more disk space, but runs much more slowly.  It
+     rewrites an entire new copy of the table and rebuilds all indexes.
+     This typically has much higher overhead than
+     <command>VACUUM</command>.  Generally, therefore, administrators
+     should avoid using <command>VACUUM FULL</command> except in the
+     most extreme cases.
+    </para>
+   </tip>
+   <note>
+    <para>
+     Although <command>VACUUM FULL</command> is technically an option
+     of the <command>VACUUM</command> command, <command>VACUUM
+      FULL</command> uses a completely different implementation.
+     <command>VACUUM FULL</command> is essentially a variant of
+     <command>CLUSTER</command>.  (The name <command>VACUUM
+      FULL</command> is historical; the original implementation was
+     somewhat closer to standard <command>VACUUM</command>.)
+    </para>
+   </note>
+   <warning>
+    <para>
+     <command>TRUNCATE</command>, <command>VACUUM FULL</command>, and
+     <command>CLUSTER</command> all require an <literal>ACCESS
+      EXCLUSIVE</literal> lock, which can be highly disruptive
+     (<command>SELECT</command>, <command>INSERT</command>,
+     <command>UPDATE</command>, and <command>DELETE</command> commands
+     will all be blocked).
+    </para>
+   </warning>
+   <warning>
+    <para>
+     <command>VACUUM FULL</command> (and <command>CLUSTER</command>)
+     temporarily uses extra disk space approximately equal to the size
+     of the table, since the old copies of the table and indexes can't
+     be released until the new ones are complete.
+    </para>
+   </warning>
   </sect2>
 
   <sect2 id="freezing-xid-space">
-- 
2.40.0



  [application/octet-stream] v1-0008-Overhaul-freezing-and-wraparound-docs.patch (47.5K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/4-v1-0008-Overhaul-freezing-and-wraparound-docs.patch)
  download | inline diff:
From b1af9724b6553a17ba42bab4df5f595428bcdbf8 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 13:04:13 -0700
Subject: [PATCH v1 8/9] Overhaul freezing and wraparound docs.

This is almost a complete rewrite.  "Preventing Transaction ID
Wraparound Failures" becomes "Freezing to manage the transaction ID
space".  This is follow-up work to commit 1de58df4, which added
page-level freezing to VACUUM.

The emphasis is now on the physical work of freezing pages.  This flows
a little better than it otherwise would due to recent structural
cleanups to maintenance.sgml; discussion about freezing now immediately
follows discussion of cleanup of dead tuples.  We still talk about the
problem of the system activating xidStopLimit protections in the same
section, but we use much less alarmist language about data corruption,
and are no longer overly concerned about the very worst case.  We don't
rescind the recommendation that users recover from an xidStopLimit
outage by using single user mode, though that seems like something we
should aim to do in the near future.

There is no longer a separate sect3 to discuss MultiXactId related
issues.  VACUUM now performs exactly the same processing steps when it
freezes a page, independent of the trigger condition.

Also describe the page-level freezing FPI optimization added by commit
1de58df4.  This is expected to trigger the majority of all freezing with
many types of workloads.
---
 doc/src/sgml/config.sgml                  |  24 +-
 doc/src/sgml/logicaldecoding.sgml         |   2 +-
 doc/src/sgml/maintenance.sgml             | 602 ++++++++++++++--------
 doc/src/sgml/ref/create_table.sgml        |   2 +-
 doc/src/sgml/ref/prepare_transaction.sgml |   2 +-
 doc/src/sgml/ref/vacuum.sgml              |   6 +-
 doc/src/sgml/ref/vacuumdb.sgml            |   4 +-
 doc/src/sgml/xact.sgml                    |   4 +-
 8 files changed, 399 insertions(+), 247 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 091a79d4f..4c1cc0e8e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -8394,7 +8394,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         Note that even when this parameter is disabled, the system
         will launch autovacuum processes if necessary to
         prevent transaction ID wraparound.  See <xref
-        linkend="vacuum-for-wraparound"/> for more information.
+        linkend="freezing-xid-space"/> for more information.
        </para>
       </listitem>
      </varlistentry>
@@ -8583,7 +8583,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         This parameter can only be set at server start, but the setting
         can be reduced for individual tables by
         changing table storage parameters.
-        For more information see <xref linkend="vacuum-for-wraparound"/>.
+        For more information see <xref linkend="freezing-xid-space"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -8612,7 +8612,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         400 million multixacts.
         This parameter can only be set at server start, but the setting can
         be reduced for individual tables by changing table storage parameters.
-        For more information see <xref linkend="vacuum-for-multixact-wraparound"/>.
+        For more information see <xref linkend="aggressive-strategy"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -9319,7 +9319,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         periodic manual <command>VACUUM</command> has a chance to run before an
         anti-wraparound autovacuum is launched for the table. For more
         information see
-        <xref linkend="vacuum-for-wraparound"/>.
+        <xref linkend="freezing-xid-space"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -9341,7 +9341,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         the value of <xref linkend="guc-autovacuum-freeze-max-age"/>, so
         that there is not an unreasonably short time between forced
         autovacuums.  For more information see <xref
-        linkend="vacuum-for-wraparound"/>.
+        linkend="freezing-xid-space"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -9357,8 +9357,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         Specifies the maximum age (in transactions) that a table's
         <structname>pg_class</structname>.<structfield>relfrozenxid</structfield>
         field can attain before <command>VACUUM</command> takes
-        extraordinary measures to avoid system-wide transaction ID
-        wraparound failure.  This is <command>VACUUM</command>'s
+        extraordinary measures to avoid
+        <link linkend="xid-stop-limit">having the system refuse to
+         allocate new transaction IDs</link>.  This is <command>VACUUM</command>'s
         strategy of last resort.  The failsafe typically triggers
         when an autovacuum to prevent transaction ID wraparound has
         already been running for some time, though it's possible for
@@ -9402,7 +9403,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         <xref linkend="guc-autovacuum-multixact-freeze-max-age"/>, so that a
         periodic manual <command>VACUUM</command> has a chance to run before an
         anti-wraparound is launched for the table.
-        For more information see <xref linkend="vacuum-for-multixact-wraparound"/>.
+        For more information see <xref linkend="aggressive-strategy"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -9423,7 +9424,7 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         the value of <xref linkend="guc-autovacuum-multixact-freeze-max-age"/>,
         so that there is not an unreasonably short time between forced
         autovacuums.
-        For more information see <xref linkend="vacuum-for-multixact-wraparound"/>.
+        For more information see <xref linkend="freezing-xid-space"/>.
        </para>
       </listitem>
      </varlistentry>
@@ -9439,8 +9440,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         Specifies the maximum age (in multixacts) that a table's
         <structname>pg_class</structname>.<structfield>relminmxid</structfield>
         field can attain before <command>VACUUM</command> takes
-        extraordinary measures to avoid system-wide multixact ID
-        wraparound failure.  This is <command>VACUUM</command>'s
+        extraordinary measures to avoid
+        <link linkend="xid-stop-limit">having the system refuse to
+         allocate new MultiXactIDs</link>.  This is <command>VACUUM</command>'s
         strategy of last resort.  The failsafe typically triggers when
         an autovacuum to prevent transaction ID wraparound has already
         been running for some time, though it's possible for the
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index cbd3aa804..80dade3be 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -353,7 +353,7 @@ postgres=# select * from pg_logical_slot_get_changes('regression_slot', NULL, NU
       because neither required WAL nor required rows from the system catalogs
       can be removed by <command>VACUUM</command> as long as they are required by a replication
       slot.  In extreme cases this could cause the database to shut down to prevent
-      transaction ID wraparound (see <xref linkend="vacuum-for-wraparound"/>).
+      transaction ID wraparound (see <xref linkend="freezing-xid-space"/>).
       So if a slot is no longer required it should be dropped.
      </para>
     </caution>
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 7476e5922..169c6f41a 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -275,15 +275,21 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
     </listitem>
 
     <listitem>
-     <simpara>To protect against loss of very old data due to
-     <firstterm>transaction ID wraparound</firstterm> or
-     <firstterm>multixact ID wraparound</firstterm>.</simpara>
+     <simpara>To maintain the system's ability to allocated new
+     transaction IDs (and new multixact IDs) through freezing.</simpara>
     </listitem>
 
     <listitem>
      <simpara>To update the visibility map, which speeds
      up <link linkend="indexes-index-only-scans">index-only
-     scans</link>.</simpara>
+     scans</link>, and helps the next <command>VACUUM</command>
+     operation avoid needlessly scanning pages that are already
+     frozen</simpara>
+    </listitem>
+
+    <listitem>
+     <simpara>To truncate obsolescent transaction status information,
+     when possible</simpara>
     </listitem>
 
     <listitem>
@@ -432,10 +438,10 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    </tip>
   </sect2>
 
-  <sect2 id="vacuum-for-wraparound">
-   <title>Preventing Transaction ID Wraparound Failures</title>
+  <sect2 id="freezing-xid-space">
+   <title>Freezing to manage the transaction ID space</title>
 
-   <indexterm zone="vacuum-for-wraparound">
+   <indexterm zone="freezing-xid-space">
     <primary>transaction ID</primary>
     <secondary>wraparound</secondary>
    </indexterm>
@@ -461,274 +467,364 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    </para>
 
    <para>
-    <xref linkend="guc-vacuum-freeze-min-age"/>
-    controls how old an XID value has to be before rows bearing that XID will be
-    frozen.  Increasing this setting may avoid unnecessary work if the
-    rows that would otherwise be frozen will soon be modified again,
-    but decreasing this setting increases
-    the number of transactions that can elapse before the table must be
-    vacuumed again.
+    <command>VACUUM</command> marks pages as
+    <emphasis>frozen</emphasis>, indicating that all eligible rows on
+    the page were inserted by a transaction that committed
+    sufficiently far in the past that the effects of the inserting
+    transaction are certain to be visible to all current and future
+    transactions.  Frozen rows are treated as if the inserting
+    transaction (the heap tuple's <structfield>xmin</structfield> XID)
+    committed <quote>infinitely far in the past</quote>, making the
+    effects of the transaction visible to all current and future MVCC
+    snapshots, forever.  Once frozen, pages are <quote>self
+     contained</quote> in the sense that all of its rows can be read
+    without ever having to consult externally stored transaction status
+    metadata (for example, transaction commit status information from
+    <filename>pg_xact</filename> is not required).
    </para>
 
    <para>
-    <command>VACUUM</command> uses the <link linkend="storage-vm">visibility map</link>
-    to determine which pages of a table must be scanned.  Normally, it
-    will skip pages that don't have any dead row versions even if those pages
-    might still have row versions with old XID values.  Therefore, normal
-    <command>VACUUM</command>s won't always freeze every old row version in the table.
-    When that happens, <command>VACUUM</command> will eventually need to perform an
-    <firstterm>aggressive vacuum</firstterm>, which will freeze all eligible unfrozen
-    XID and MXID values, including those from all-visible but not all-frozen pages.
-    In practice most tables require periodic aggressive vacuuming.
-    <xref linkend="guc-vacuum-freeze-table-age"/>
-    controls when <command>VACUUM</command> does that: all-visible but not all-frozen
-    pages are scanned if the number of transactions that have passed since the
-    last such scan is greater than <varname>vacuum_freeze_table_age</varname> minus
-    <varname>vacuum_freeze_min_age</varname>. Setting
-    <varname>vacuum_freeze_table_age</varname> to 0 forces <command>VACUUM</command> to
-    always use its aggressive strategy.
+    Without freezing, the system will eventually <link
+     linkend="xid-stop-limit">refuse to allocate new transaction
+     IDs</link>, making <acronym>DML</acronym> statements throw errors
+    until such time as <command>VACUUM</command> can restore the
+    system's ability to allocate new transaction IDs.  The system is
+    unable to recognize distances of more than about 2.1 billion
+    transactions between any two unfrozen XIDs.  The only safe option
+    that remains is to disallow allocating new XIDs until
+    <command>VACUUM</command> has performed the steps required to make
+    sure that the <quote>distance</quote> invariant is never violated.
    </para>
 
    <para>
-    The maximum time that a table can go unvacuumed is two billion
-    transactions minus the <varname>vacuum_freeze_min_age</varname> value at
-    the time of the last aggressive vacuum. If it were to go
-    unvacuumed for longer than
-    that, data loss could result.  To ensure that this does not happen,
-    autovacuum is invoked on any table that might contain unfrozen rows with
-    XIDs older than the age specified by the configuration parameter <xref
-    linkend="guc-autovacuum-freeze-max-age"/>.  (This will happen even if
-    autovacuum is disabled.)
+    <xref linkend="guc-vacuum-freeze-min-age"/> can be used to control
+    when freezing takes place.  When <command>VACUUM</command> scans a
+    heap page containing even one XID that already attained an age
+    exceeding this value, the page is frozen.  All tuples from the page
+    are frozen, making the page suitable for long-term storage (their
+    is no longer any possible need to interpret the contents of the
+    page using external transaction status information).  Increasing
+    this setting may avoid unnecessary work if the pages that would
+    otherwise be frozen will soon be modified again, but decreasing
+    this setting makes it more likely that some future
+    <command>VACUUM</command> operation will need to perform an
+    excessive amount of <quote>catch-up freezing</quote>, all in one go.
+   </para>
+
+   <indexterm>
+    <primary>MultiXactId</primary>
+   </indexterm>
+
+   <indexterm>
+    <primary>freezing</primary>
+    <secondary>of multixact IDs</secondary>
+   </indexterm>
+
+   <para>
+    <firstterm>Multixact IDs</firstterm> are used to support row
+    locking by multiple transactions.  Since there is only limited
+    space in a tuple header to store lock information, that
+    information is encoded as a <quote>multiple transaction
+     ID</quote>, or multixact ID for short, whenever there is more
+    than one transaction concurrently locking a row.  Information
+    about which transaction IDs are included in any particular
+    multixact ID is stored separately, and only the multixact ID
+    appears in the <structfield>xmax</structfield> field in the tuple
+    header.  Like transaction IDs, multixact IDs are implemented as a
+    32-bit counter and corresponding storage.
+    <quote>Freezing</quote> of multixact IDs is also required, though
+    this actually means setting <structfield>xmax</structfield> to
+    <literal>InvalidTransactionId</literal>.
+    <!-- The following parenthetical statement isn't strictly true,
+    but it is true in spirit.  VACUUM practically always processes
+    xmax fields this way in practice. -->
+    (Actually, <emphasis>any</emphasis> <structfield>xmax</structfield>
+    field is processed in the same way when its page is frozen,
+    including <structfield>xmax</structfield> fields that contain
+    simple XIDs.)
    </para>
 
    <para>
-    This implies that if a table is not otherwise vacuumed,
-    autovacuum will be invoked on it approximately once every
-    <varname>autovacuum_freeze_max_age</varname> minus
-    <varname>vacuum_freeze_min_age</varname> transactions.
-    For tables that are regularly vacuumed for space reclamation purposes,
-    this is of little importance.  However, for static tables
-    (including tables that receive inserts, but no updates or deletes),
-    there is no need to vacuum for space reclamation, so it can
-    be useful to try to maximize the interval between forced autovacuums
-    on very large static tables.  Obviously one can do this either by
-    increasing <varname>autovacuum_freeze_max_age</varname> or decreasing
-    <varname>vacuum_freeze_min_age</varname>.
+    <xref linkend="guc-vacuum-multixact-freeze-min-age"/> can also
+    influence which pages <command>VACUUM</command> freezes.  Like
+    <varname>vacuum_freeze_min_age</varname>, the setting triggers
+    page-level freezing.  However,
+    <varname>vacuum_multixact_freeze_min_age</varname> uses
+    MultiXactIds (not XIDs) to measure <quote>age</quote>.
+   </para>
+
+   <note>
+    <para>
+     In <productname>PostgreSQL</productname> versions before 16,
+     freezing was triggered at the level of individual
+     <structfield>xmin</structfield> and
+     <structfield>xmax</structfield> fields.  The decision to freeze
+     (or not freeze) is now made at the level of whole heap pages, at
+     the point that they are scanned by <command>VACUUM</command>.
+    </para>
+   </note>
+
+   <para>
+    In general, the major cost of freezing is the additional
+    <acronym>WAL</acronym> volume.  That's why
+    <command>VACUUM</command> doesn't just freeze every eligible tuple
+    at the earliest opportunity: freezing will go to waste in cases
+    where a recently frozen tuple soon goes on to be deleted anyway.
+    Managing the added <acronym>WAL</acronym> volume from freezing
+    over time is an important consideration for
+    <command>VACUUM</command>.
    </para>
 
    <para>
-    The effective maximum for <varname>vacuum_freeze_table_age</varname> is 0.95 *
-    <varname>autovacuum_freeze_max_age</varname>; a setting higher than that will be
-    capped to the maximum. A value higher than
-    <varname>autovacuum_freeze_max_age</varname> wouldn't make sense because an
-    anti-wraparound autovacuum would be triggered at that point anyway, and
-    the 0.95 multiplier leaves some breathing room to run a manual
-    <command>VACUUM</command> before that happens.  As a rule of thumb,
-    <command>vacuum_freeze_table_age</command> should be set to a value somewhat
-    below <varname>autovacuum_freeze_max_age</varname>, leaving enough gap so that
-    a regularly scheduled <command>VACUUM</command> or an autovacuum triggered by
-    normal delete and update activity is run in that window.  Setting it too
-    close could lead to anti-wraparound autovacuums, even though the table
-    was recently vacuumed to reclaim space, whereas lower values lead to more
-    frequent aggressive vacuuming.
+    <command>VACUUM</command> also triggers freezing of pages in cases
+    where it already proved necessary to write out an
+    <acronym>FPI</acronym> to the <acronym>WAL</acronym> as torn page
+    protection (as part of removing dead tuples).  The extra
+    <acronym>WAL</acronym> volume from proactive freezing is
+    insignificant compared to the cost of the <acronym>FPI</acronym>.
+    It is very likely (though not quite certain) that the overall
+    volume of <acronym>WAL</acronym> will be lower in the long term
+    with tables that have most freezing triggered by the
+    <acronym>FPI</acronym> mechanism, since (at least on average)
+    future <command>VACUUM</command>s shouldn't have to write a second
+    <acronym>FPI</acronym> out much later on, when freezing becomes
+    strictly necessary.  The <acronym>FPI</acronym> freezing mechanism
+    is just an alternative trigger criteria for freezing all eligible
+    tuples on the page.  In general, <command>VACUUM</command> freezes
+    pages without regard to the condition that triggered freezing.
+    The physical modifications to the page (how tuples are processed)
+    is decoupled from the mechanism that decides if those
+    modifications should happen at all.
    </para>
 
    <para>
-    The sole disadvantage of increasing <varname>autovacuum_freeze_max_age</varname>
-    (and <varname>vacuum_freeze_table_age</varname> along with it) is that
-    the <filename>pg_xact</filename> and <filename>pg_commit_ts</filename>
-    subdirectories of the database cluster will take more space, because it
-    must store the commit status and (if <varname>track_commit_timestamp</varname> is
-    enabled) timestamp of all transactions back to
-    the <varname>autovacuum_freeze_max_age</varname> horizon.  The commit status uses
-    two bits per transaction, so if
-    <varname>autovacuum_freeze_max_age</varname> is set to its maximum allowed value
-    of two billion, <filename>pg_xact</filename> can be expected to grow to about half
-    a gigabyte and <filename>pg_commit_ts</filename> to about 20GB.  If this
-    is trivial compared to your total database size,
-    setting <varname>autovacuum_freeze_max_age</varname> to its maximum allowed value
-    is recommended.  Otherwise, set it depending on what you are willing to
-    allow for <filename>pg_xact</filename> and <filename>pg_commit_ts</filename> storage.
-    (The default, 200 million transactions, translates to about 50MB
-    of <filename>pg_xact</filename> storage and about 2GB of <filename>pg_commit_ts</filename>
-    storage.)
+    <command>VACUUM</command> may not be able to freeze every tuple's
+    <structfield>xmin</structfield> in relatively rare cases.  The
+    criteria that determines eligibility for freezing is exactly the
+    same as the one that determines if a deleted tuple should be
+    considered <literal>removable</literal> or merely <literal>dead
+     but not yet removable</literal> (namely, the XID-based
+    <literal>removable cutoff</literal>).
    </para>
 
-   <para>
-    One disadvantage of decreasing <varname>vacuum_freeze_min_age</varname> is that
-    it might cause <command>VACUUM</command> to do useless work: freezing a row
-    version is a waste of time if the row is modified
-    soon thereafter (causing it to acquire a new XID).  So the setting should
-    be large enough that rows are not frozen until they are unlikely to change
-    any more.
-   </para>
+   <sect3 id="aggressive-strategy">
+    <title><command>VACUUM</command>'s aggressive strategy</title>
+    <para>
+     To track the age of the oldest unfrozen XIDs in a database,
+     <command>VACUUM</command> stores XID statistics in the system
+     tables <structname>pg_class</structname> and
+     <structname>pg_database</structname>.  In particular, the
+     <structfield>relfrozenxid</structfield> column of a table's
+     <structname>pg_class</structname> row contains the oldest
+     remaining unfrozen XID at the end of the most recent
+     <command>VACUUM</command> that successfully advanced
+     <structfield>relfrozenxid</structfield>.  Similarly, the
+     <structfield>datfrozenxid</structfield> column of a database's
+     <structname>pg_database</structname> row is a lower bound on the
+     unfrozen XIDs appearing in that database &mdash; it is just the
+     minimum of the per-table <structfield>relfrozenxid</structfield>
+     values within the database.
+    </para>
 
-   <para>
-    To track the age of the oldest unfrozen XIDs in a database,
-    <command>VACUUM</command> stores XID
-    statistics in the system tables <structname>pg_class</structname> and
-    <structname>pg_database</structname>.  In particular,
-    the <structfield>relfrozenxid</structfield> column of a table's
-    <structname>pg_class</structname> row contains the oldest remaining unfrozen
-    XID at the end of the most recent <command>VACUUM</command> that successfully
-    advanced <structfield>relfrozenxid</structfield> (typically the most recent
-    aggressive VACUUM).  Similarly, the
-    <structfield>datfrozenxid</structfield> column of a database's
-    <structname>pg_database</structname> row is a lower bound on the unfrozen XIDs
-    appearing in that database &mdash; it is just the minimum of the
-    per-table <structfield>relfrozenxid</structfield> values within the database.
-    A convenient way to
-    examine this information is to execute queries such as:
+    <para>
+     <command>VACUUM</command> uses the <link
+      linkend="storage-vm">visibility map</link> to determine which
+     pages of a table must be scanned.  Normally, it will skip pages
+     that don't have any dead row versions even if those pages might
+     still have row versions with old XID values.  Therefore, normal
+     <command>VACUUM</command>s usually won't freeze
+     <emphasis>every</emphasis> page with an old row version in the
+     table.  Most individual tables will eventually need an
+     <firstterm>aggressive vacuum</firstterm>, which will reliably
+     freeze all pages with XID and MXID values older than
+     <varname>vacuum_freeze_min_age</varname>, including those from
+     all-visible but not all-frozen pages.  <xref
+      linkend="guc-vacuum-freeze-table-age"/> controls when
+     <command>VACUUM</command> must use its aggressive strategy.
+     Since the setting is applied against
+     <literal>age(relfrozenxid)</literal>, settings like
+     <varname>vacuum_freeze_min_age</varname> may influence the exact
+     cadence of aggressive vacuuming.  Setting
+     <varname>vacuum_freeze_table_age</varname> to 0 forces
+     <command>VACUUM</command> to always use its aggressive strategy.
+    </para>
+
+    <note>
+     <para>
+      In practice most tables require periodic aggressive vacuuming.
+      However, some individual non-aggressive
+      <command>VACUUM</command> operations may be able to advance
+      <structfield>relfrozenxid</structfield> and/or
+      <structfield>relminmxid</structfield>.  This is most common in
+      small, frequently modified tables, where
+      <command>VACUUM</command> happens to scan all pages (or at least
+      all pages not marked all-frozen) in the course of removing dead
+      tuples.
+     </para>
+    </note>
+
+    <para>
+     The maximum time that a table can go unvacuumed is about two
+     billion transactions. If it were to go unvacuumed for longer than
+     that, the system will <link linkend="xid-stop-limit">refuse to
+      allocate new transaction IDs</link>, temporarily rendering the
+     database read-only.  To ensure that this never happens,
+     autovacuum is invoked on any table that might contain unfrozen
+     rows with XIDs older than the age specified by the configuration
+     parameter <xref linkend="guc-autovacuum-freeze-max-age"/>.  (This
+     will happen even if autovacuum is disabled.)
+    </para>
+
+    <para>
+     <!-- This isn't strictly true, since anti-wraparound autovacuuming
+     merely implies aggressive mode -->
+     In practice all anti-wraparound autovacuums will use
+     <command>VACUUM</command>'s aggressive strategy.  This is assured
+     because the effective value of
+     <varname>vacuum_freeze_table_age</varname> is
+     <quote>clamped</quote> to a value no greater than 95% of the
+     current value of <varname>autovacuum_freeze_max_age</varname>.
+     As a rule of thumb, <command>vacuum_freeze_table_age</command>
+     should be set to a value somewhat below
+     <varname>autovacuum_freeze_max_age</varname>, leaving enough gap
+     so that a regularly scheduled <command>VACUUM</command> or an
+     autovacuum triggered by inserts, updates and deletes is run in
+     that window.  Anti-wraparound autovacuums can be avoided
+     altogether in tables that reliably receive
+     <emphasis>some</emphasis> <command>VACUUM</command>s that use the
+     aggressive strategy.
+    </para>
+
+    <note>
+     <para>
+      There is no fundamental difference between a
+      <command>VACUUM</command> run during anti-wraparound
+      autovacuuming and a <command>VACUUM</command> that happens to
+      use the aggressive strategy (whether run by autovacuum or
+      manually issued).
+     </para>
+    </note>
+
+    <para>
+     A convenient way to examine information about
+     <structfield>relfrozenxid</structfield> and
+     <structfield>relminmxid</structfield> is to execute queries such as:
 
 <programlisting>
 SELECT c.oid::regclass as table_name,
-       greatest(age(c.relfrozenxid),age(t.relfrozenxid)) as age
+greatest(age(c.relfrozenxid),
+         age(t.relfrozenxid)) as xid_age,
+mxid_age(c.relminmxid)
 FROM pg_class c
 LEFT JOIN pg_class t ON c.reltoastrelid = t.oid
 WHERE c.relkind IN ('r', 'm');
 
-SELECT datname, age(datfrozenxid) FROM pg_database;
+SELECT datname,
+age(datfrozenxid) as xid_age,
+mxid_age(datminmxid)
+FROM pg_database;
 </programlisting>
 
-    The <literal>age</literal> column measures the number of transactions from the
-    cutoff XID to the current transaction's XID.
-   </para>
-
-   <tip>
-    <para>
-     When the <command>VACUUM</command> command's <literal>VERBOSE</literal>
-     parameter is specified, <command>VACUUM</command> prints various
-     statistics about the table.  This includes information about how
-     <structfield>relfrozenxid</structfield> and
-     <structfield>relminmxid</structfield> advanced, and the number of
-     newly frozen pages.  The same details appear in the server log when
-     autovacuum logging (controlled by <xref
-      linkend="guc-log-autovacuum-min-duration"/>) reports on a
-     <command>VACUUM</command> operation executed by autovacuum.
+     The <literal>age</literal> column measures the number of
+     transactions from the cutoff XID to the next unallocated
+     transactions XID.  The <literal>mxid_age</literal> column
+     measures the number of MultiXactIds from the cutoff MultiXactId
+     to the next unallocated MultiXactId.
     </para>
-   </tip>
 
-   <para>
-    <command>VACUUM</command> normally only scans pages that have been modified
-    since the last vacuum, but <structfield>relfrozenxid</structfield> can only be
-    advanced when every page of the table
-    that might contain unfrozen XIDs is scanned.  This happens when
-    <structfield>relfrozenxid</structfield> is more than
-    <varname>vacuum_freeze_table_age</varname> transactions old, when
-    <command>VACUUM</command>'s <literal>FREEZE</literal> option is used, or when all
-    pages that are not already all-frozen happen to
-    require vacuuming to remove dead row versions. When <command>VACUUM</command>
-    scans every page in the table that is not already all-frozen, it should
-    set <literal>age(relfrozenxid)</literal> to a value just a little more than the
-    <varname>vacuum_freeze_min_age</varname> setting
-    that was used (more by the number of transactions started since the
-    <command>VACUUM</command> started).  <command>VACUUM</command>
-    will set <structfield>relfrozenxid</structfield> to the oldest XID
-    that remains in the table, so it's possible that the final value
-    will be much more recent than strictly required.
-    If no <structfield>relfrozenxid</structfield>-advancing
-    <command>VACUUM</command> is issued on the table until
-    <varname>autovacuum_freeze_max_age</varname> is reached, an autovacuum will soon
-    be forced for the table.
-   </para>
+    <tip>
+     <para>
+      When the <command>VACUUM</command> command's
+      <literal>VERBOSE</literal> parameter is specified,
+      <command>VACUUM</command> prints various statistics about the
+      table.  This includes information about how
+      <structfield>relfrozenxid</structfield> and
+      <structfield>relminmxid</structfield> advanced, and the number
+      of newly frozen pages.  The same details appear in the server
+      log when autovacuum logging (controlled by <xref
+       linkend="guc-log-autovacuum-min-duration"/>) reports on a
+      <command>VACUUM</command> operation executed by autovacuum.
+     </para>
+    </tip>
+   </sect3>
 
-   <para>
-    If for some reason autovacuum fails to clear old XIDs from a table, the
-    system will begin to emit warning messages like this when the database's
-    oldest XIDs reach forty million transactions from the wraparound point:
+   <sect3 id="xid-stop-limit">
+    <title><literal>xidStopLimit</literal> mode</title>
+    <para>
+     If for some reason autovacuum utterly fails to advance any
+     table's <structfield>relfrozenxid</structfield> or
+     <structfield>relminmxid</structfield>, the system will begin to
+     emit warning messages like this when the database's oldest XIDs
+     reach forty million transactions from the wraparound point:
 
 <programlisting>
 WARNING:  database "mydb" must be vacuumed within 39985967 transactions
 HINT:  To avoid a database shutdown, execute a database-wide VACUUM in that database.
 </programlisting>
 
-    (A manual <command>VACUUM</command> should fix the problem, as suggested by the
-    hint; but note that the <command>VACUUM</command> must be performed by a
-    superuser, else it will fail to process system catalogs and thus not
-    be able to advance the database's <structfield>datfrozenxid</structfield>.)
-    If these warnings are
-    ignored, the system will shut down and refuse to start any new
-    transactions once there are fewer than three million transactions left
-    until wraparound:
+     (A manual <command>VACUUM</command> should fix the problem, as suggested by the
+     hint; but note that the <command>VACUUM</command> must be performed by a
+     superuser, else it will fail to process system catalogs and thus not
+     be able to advance the database's <structfield>datfrozenxid</structfield>.)
+     If these warnings are ignored, the system will eventually refuse
+     to start any new transactions.  This happens at the point that
+     there are fewer than three million transactions left:
 
 <programlisting>
 ERROR:  database is not accepting commands to avoid wraparound data loss in database "mydb"
 HINT:  Stop the postmaster and vacuum that database in single-user mode.
 </programlisting>
 
-    The three-million-transaction safety margin exists to let the
-    administrator recover without data loss, by manually executing the
-    required <command>VACUUM</command> commands.  However, since the system will not
-    execute commands once it has gone into the safety shutdown mode,
-    the only way to do this is to stop the server and start the server in single-user
-    mode to execute <command>VACUUM</command>.  The shutdown mode is not enforced
-    in single-user mode.  See the <xref linkend="app-postgres"/> reference
-    page for details about using single-user mode.
-   </para>
-
-   <sect3 id="vacuum-for-multixact-wraparound">
-    <title>Multixacts and Wraparound</title>
-
-    <indexterm>
-     <primary>MultiXactId</primary>
-    </indexterm>
-
-    <indexterm>
-     <primary>wraparound</primary>
-     <secondary>of multixact IDs</secondary>
-    </indexterm>
-
-    <para>
-     <firstterm>Multixact IDs</firstterm> are used to support row locking by
-     multiple transactions.  Since there is only limited space in a tuple
-     header to store lock information, that information is encoded as
-     a <quote>multiple transaction ID</quote>, or multixact ID for short,
-     whenever there is more than one transaction concurrently locking a
-     row.  Information about which transaction IDs are included in any
-     particular multixact ID is stored separately in
-     the <filename>pg_multixact</filename> subdirectory, and only the multixact ID
-     appears in the <structfield>xmax</structfield> field in the tuple header.
-     Like transaction IDs, multixact IDs are implemented as a
-     32-bit counter and corresponding storage, all of which requires
-     careful aging management, storage cleanup, and wraparound handling.
-     There is a separate storage area which holds the list of members in
-     each multixact, which also uses a 32-bit counter and which must also
-     be managed.
+     The three-million-transaction safety margin exists to let the
+     administrator recover without data loss, by manually executing the
+     required <command>VACUUM</command> commands.  However, since the system will not
+     execute commands once it has gone into the safety shutdown mode,
+     the only way to do this is to stop the server and start the server in single-user
+     mode to execute <command>VACUUM</command>.  The shutdown mode is not enforced
+     in single-user mode.  See the <xref linkend="app-postgres"/> reference
+     page for details about using single-user mode.
     </para>
 
     <para>
-     Whenever <command>VACUUM</command> scans any part of a table, it will replace
-     any multixact ID it encounters which is older than
-     <xref linkend="guc-vacuum-multixact-freeze-min-age"/>
-     by a different value, which can be the zero value, a single
-     transaction ID, or a newer multixact ID.  For each table,
-     <structname>pg_class</structname>.<structfield>relminmxid</structfield> stores the oldest
-     possible multixact ID still appearing in any tuple of that table.
-     If this value is older than
-     <xref linkend="guc-vacuum-multixact-freeze-table-age"/>, an aggressive
-     vacuum is forced.  As discussed in the previous section, an aggressive
-     vacuum means that only those pages which are known to be all-frozen will
-     be skipped.  <function>mxid_age()</function> can be used on
-     <structname>pg_class</structname>.<structfield>relminmxid</structfield> to find its age.
+     Anything that influences when and how
+     <structfield>relfrozenxid</structfield> and
+     <structfield>relminmxid</structfield> advance will also directly
+     affect the high watermark storage overhead from storing a great
+     deal of historical transaction status information.  The
+     additional <link linkend="vacuum-truncate-pg-xact">space
+      overhead</link> is usually of fairly minimal concern.  It is
+     noted as an additional downside of allowing the system to get
+     close to <literal>xidStopLimit</literal> for the sake of
+     completeness.
     </para>
 
-    <para>
-     Aggressive <command>VACUUM</command>s, regardless of what causes
-     them, are <emphasis>guaranteed</emphasis> to be able to advance
-     the table's <structfield>relminmxid</structfield>.
-     Eventually, as all tables in all databases are scanned and their
-     oldest multixact values are advanced, on-disk storage for older
-     multixacts can be removed.
-    </para>
+    <note>
+     <title>Historical Note</title>
+     <para>
+      The term <quote>wraparound</quote> is inaccurate.  Also, there
+      is no <quote>data loss</quote> here &mdash; the message is
+      simply wrong.
+     </para>
+     <para>
+      XXX: We really need to fix the situation with single user mode
+      to put things on a good footing.
+     </para>
+    </note>
 
     <para>
-     As a safety device, an aggressive vacuum scan will
-     occur for any table whose multixact-age is greater than <xref
-     linkend="guc-autovacuum-multixact-freeze-max-age"/>.  Also, if the
-     storage occupied by multixacts members exceeds 2GB, aggressive vacuum
-     scans will occur more often for all tables, starting with those that
-     have the oldest multixact-age.  Both of these kinds of aggressive
-     scans will occur even if autovacuum is nominally disabled.
+     In emergencies, <command>VACUUM</command> will take extraordinary
+     measures to avoid <literal>xidStopLimit</literal> mode.  A
+     failsafe mechanism is triggered when thresholds controlled by
+     <xref linkend="guc-vacuum-failsafe-age"/> and <xref
+      linkend="guc-vacuum-multixact-failsafe-age"/> are reached.  The
+     failsafe prioritizes advancing
+     <structfield>relfrozenxid</structfield> and/or
+     <structfield>relminmxid</structfield> as quickly as possible.
+     Once the failsafe triggers, <command>VACUUM</command> bypasses
+     all remaining non-essential maintenance tasks, and stops applying
+     any cost-based delay that was in effect.  Any <glossterm
+     linkend="glossary-buffer-access-strategy">Buffer Access
+     Strategy</glossterm> in use will also be disabled.
     </para>
    </sect3>
   </sect2>
@@ -766,6 +862,58 @@ HINT:  Stop the postmaster and vacuum that database in single-user mode.
    </para>
   </sect2>
 
+  <sect2 id="vacuum-truncate-pg-xact">
+   <title>Truncating transaction status information</title>
+   <para>
+    As noted in <xref linkend="xid-stop-limit"/>, anything that
+    influences when and how <structfield>relfrozenxid</structfield> and
+    <structfield>relminmxid</structfield> advance will also directly
+    affect the high watermark storage overhead needed to store
+    historical transaction status information.  For example,
+    increasing <varname>autovacuum_freeze_max_age</varname> (and
+    <varname>vacuum_freeze_table_age</varname> along with it) will
+    make the <filename>pg_xact</filename> and
+    <filename>pg_commit_ts</filename> subdirectories of the database
+    cluster take more space, because they store the commit status and
+    (if <varname>track_commit_timestamp</varname> is enabled)
+    timestamp of all transactions back to the
+    <varname>datfrozenxid</varname> horizon (the earliest
+    <varname>datfrozenxid</varname> in the entire cluster).
+   </para>
+   <para>
+    The commit status uses two bits per transaction.  The default
+    <varname>autovacuum_freeze_max_age</varname> setting of 200
+    million transactions translates to about 50MB of
+    <filename>pg_xact</filename> storage.  When
+    <varname>track_commit_timestamp</varname> is enabled, about 2GB of
+    <filename>pg_commit_ts</filename> storage will also be required.
+   </para>
+   <para>
+    MultiXactId status information is implemented as two separate
+    <acronym>SLRU</acronym> storage areas:
+    <filename>pg_multixact/members</filename>, and
+    <filename>pg_multixact/offsets</filename>.  There is no simple
+    formula to determine the storage overhead per MultiXactId, since
+    MultiXactIds have a variable number of member XIDs.
+   </para>
+   <para>
+    Truncating of transaction status information is only possible at
+    the end of <command>VACUUM</command>s that advance
+    <structfield>relfrozenxid</structfield> (in the case of
+    <filename>pg_xact</filename> and
+    <filename>pg_commit_ts</filename>) or
+    <structfield>relminmxid</structfield> (in the case of
+    (<filename>pg_multixact/members</filename> and
+    <filename>pg_multixact/offsets</filename>) of whatever table
+    happened to have the oldest value in the cluster when the
+    <command>VACUUM</command> began.  This typically happens very
+    infrequently, often during <link
+     linkend="aggressive-strategy">aggressive strategy</link>
+    <command>VACUUM</command>s of one of the database's largest
+    tables.
+   </para>
+  </sect2>
+
   <sect2 id="vacuum-for-statistics">
    <title>Updating Planner Statistics</title>
 
@@ -881,7 +1029,7 @@ HINT:  Stop the postmaster and vacuum that database in single-user mode.
    </tip>
 
   </sect2>
-</sect1>
+ </sect1>
 
 
  <sect1 id="routine-reindex">
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 10ef699fa..8aa332fcf 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1515,7 +1515,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      and/or <command>ANALYZE</command> operations on this table following the rules
      discussed in <xref linkend="autovacuum"/>.
      If false, this table will not be autovacuumed, except to prevent
-     transaction ID wraparound. See <xref linkend="vacuum-for-wraparound"/> for
+     transaction ID wraparound. See <xref linkend="freezing-xid-space"/> for
      more about wraparound prevention.
      Note that the autovacuum daemon does not run at all (except to prevent
      transaction ID wraparound) if the <xref linkend="guc-autovacuum"/>
diff --git a/doc/src/sgml/ref/prepare_transaction.sgml b/doc/src/sgml/ref/prepare_transaction.sgml
index f4f6118ac..ede50d6f7 100644
--- a/doc/src/sgml/ref/prepare_transaction.sgml
+++ b/doc/src/sgml/ref/prepare_transaction.sgml
@@ -128,7 +128,7 @@ PREPARE TRANSACTION <replaceable class="parameter">transaction_id</replaceable>
     This will interfere with the ability of <command>VACUUM</command> to reclaim
     storage, and in extreme cases could cause the database to shut down
     to prevent transaction ID wraparound (see <xref
-    linkend="vacuum-for-wraparound"/>).  Keep in mind also that the transaction
+    linkend="freezing-xid-space"/>).  Keep in mind also that the transaction
     continues to hold whatever locks it held.  The intended usage of the
     feature is that a prepared transaction will normally be committed or
     rolled back as soon as an external transaction manager has verified that
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml
index 57bc4c23e..0c28604a6 100644
--- a/doc/src/sgml/ref/vacuum.sgml
+++ b/doc/src/sgml/ref/vacuum.sgml
@@ -123,7 +123,9 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
     <term><literal>FREEZE</literal></term>
     <listitem>
      <para>
-      Selects aggressive <quote>freezing</quote> of tuples.
+      Makes <quote>freezing</quote> <emphasis>maximally</emphasis>
+      aggressive, and forces <command>VACUUM</command> to use its
+      <link linkend="aggressive-strategy">aggressive strategy</link>.
       Specifying <literal>FREEZE</literal> is equivalent to performing
       <command>VACUUM</command> with the
       <xref linkend="guc-vacuum-freeze-min-age"/> and
@@ -219,7 +221,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
       there are many dead tuples in the table.  This may be useful
       when it is necessary to make <command>VACUUM</command> run as
       quickly as possible to avoid imminent transaction ID wraparound
-      (see <xref linkend="vacuum-for-wraparound"/>).  However, the
+      (see <xref linkend="freezing-xid-space"/>).  However, the
       wraparound failsafe mechanism controlled by <xref
        linkend="guc-vacuum-failsafe-age"/>  will generally trigger
       automatically to avoid transaction ID wraparound failure, and
diff --git a/doc/src/sgml/ref/vacuumdb.sgml b/doc/src/sgml/ref/vacuumdb.sgml
index da2393783..b61d523c2 100644
--- a/doc/src/sgml/ref/vacuumdb.sgml
+++ b/doc/src/sgml/ref/vacuumdb.sgml
@@ -233,7 +233,7 @@ PostgreSQL documentation
         ID age of at least <replaceable class="parameter">mxid_age</replaceable>.
         This setting is useful for prioritizing tables to process to prevent
         multixact ID wraparound (see
-        <xref linkend="vacuum-for-multixact-wraparound"/>).
+        <xref linkend="freezing-xid-space"/>).
        </para>
        <para>
         For the purposes of this option, the multixact ID age of a relation is
@@ -254,7 +254,7 @@ PostgreSQL documentation
         transaction ID age of at least
         <replaceable class="parameter">xid_age</replaceable>.  This setting
         is useful for prioritizing tables to process to prevent transaction
-        ID wraparound (see <xref linkend="vacuum-for-wraparound"/>).
+        ID wraparound (see <xref linkend="freezing-xid-space"/>).
        </para>
        <para>
         For the purposes of this option, the transaction ID age of a relation
diff --git a/doc/src/sgml/xact.sgml b/doc/src/sgml/xact.sgml
index b467660ee..e18ad8fd3 100644
--- a/doc/src/sgml/xact.sgml
+++ b/doc/src/sgml/xact.sgml
@@ -49,7 +49,7 @@
 
   <para>
    The internal transaction ID type <type>xid</type> is 32 bits wide
-   and <link linkend="vacuum-for-wraparound">wraps around</link> every
+   and <link linkend="freezing-xid-space">wraps around</link> every
    4 billion transactions. A 32-bit epoch is incremented during each
    wraparound. There is also a 64-bit type <type>xid8</type> which
    includes this epoch and therefore does not wrap around during the
@@ -100,7 +100,7 @@
    rows and can be inspected using the <xref linkend="pgrowlocks"/>
    extension.  Row-level read locks might also require the assignment
    of multixact IDs (<literal>mxid</literal>;  see <xref
-   linkend="vacuum-for-multixact-wraparound"/>).
+   linkend="freezing-xid-space"/>).
   </para>
  </sect1>
 
-- 
2.40.0



  [application/octet-stream] v1-0006-Merge-basic-vacuuming-sect2-into-sect1-introducti.patch (6.2K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/5-v1-0006-Merge-basic-vacuuming-sect2-into-sect1-introducti.patch)
  download | inline diff:
From 564d28dfd8d9347affd9205f9f7fd367c9b186a4 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 11:44:45 -0700
Subject: [PATCH v1 6/9] Merge "basic vacuuming" sect2 into sect1 introduction.

This doesn't change any of the content itself.  It just merges the
original text into the sect1 text that immediately preceded it.

This is preparation for the next commit, which will remove most of the
text "relocated" in this commit.  This structure should make things a
little easier for doc translators.

This commit is the last one that could be considered mechanical
restructuring/refactoring of existing text.
---
 doc/src/sgml/maintenance.sgml | 106 ++++++++++++++++------------------
 1 file changed, 51 insertions(+), 55 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index f554e12bf..2e18a078a 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -266,68 +266,64 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    to skim this material to help them understand and adjust autovacuuming.
   </para>
 
-  <sect2 id="vacuum-basics">
-   <title>Vacuuming Basics</title>
+  <para>
+   <productname>PostgreSQL</productname>'s
+   <link linkend="sql-vacuum"><command>VACUUM</command></link> command has to
+   process each table on a regular basis for several reasons:
 
-   <para>
-    <productname>PostgreSQL</productname>'s
-    <link linkend="sql-vacuum"><command>VACUUM</command></link> command has to
-    process each table on a regular basis for several reasons:
+   <orderedlist>
+    <listitem>
+     <simpara>To recover or reuse disk space occupied by updated or deleted
+     rows.</simpara>
+    </listitem>
 
-    <orderedlist>
-     <listitem>
-      <simpara>To recover or reuse disk space occupied by updated or deleted
-      rows.</simpara>
-     </listitem>
+    <listitem>
+     <simpara>To protect against loss of very old data due to
+     <firstterm>transaction ID wraparound</firstterm> or
+     <firstterm>multixact ID wraparound</firstterm>.</simpara>
+    </listitem>
 
-     <listitem>
-      <simpara>To protect against loss of very old data due to
-      <firstterm>transaction ID wraparound</firstterm> or
-      <firstterm>multixact ID wraparound</firstterm>.</simpara>
-     </listitem>
+    <listitem>
+     <simpara>To update the visibility map, which speeds
+     up <link linkend="indexes-index-only-scans">index-only
+     scans</link>.</simpara>
+    </listitem>
 
-     <listitem>
-      <simpara>To update the visibility map, which speeds
-      up <link linkend="indexes-index-only-scans">index-only
-      scans</link>.</simpara>
-     </listitem>
+    <listitem>
+     <simpara>To update data statistics used by the
+     <productname>PostgreSQL</productname> query planner.</simpara>
+    </listitem>
+   </orderedlist>
 
-     <listitem>
-      <simpara>To update data statistics used by the
-      <productname>PostgreSQL</productname> query planner.</simpara>
-     </listitem>
-    </orderedlist>
+   Each of these reasons dictates performing <command>VACUUM</command> operations
+   of varying frequency and scope, as explained in the following subsections.
+  </para>
 
-    Each of these reasons dictates performing <command>VACUUM</command> operations
-    of varying frequency and scope, as explained in the following subsections.
-   </para>
+  <para>
+   There are two variants of <command>VACUUM</command>: standard <command>VACUUM</command>
+   and <command>VACUUM FULL</command>.  <command>VACUUM FULL</command> can reclaim more
+   disk space but runs much more slowly.  Also,
+   the standard form of <command>VACUUM</command> can run in parallel with production
+   database operations.  (Commands such as <command>SELECT</command>,
+   <command>INSERT</command>, <command>UPDATE</command>, and
+   <command>DELETE</command> will continue to function normally, though you
+   will not be able to modify the definition of a table with commands such as
+   <command>ALTER TABLE</command> while it is being vacuumed.)
+   <command>VACUUM FULL</command> requires an
+   <literal>ACCESS EXCLUSIVE</literal> lock on the table it is
+   working on, and therefore cannot be done in parallel with other use
+   of the table.  Generally, therefore,
+   administrators should strive to use standard <command>VACUUM</command> and
+   avoid <command>VACUUM FULL</command>.
+  </para>
 
-   <para>
-    There are two variants of <command>VACUUM</command>: standard <command>VACUUM</command>
-    and <command>VACUUM FULL</command>.  <command>VACUUM FULL</command> can reclaim more
-    disk space but runs much more slowly.  Also,
-    the standard form of <command>VACUUM</command> can run in parallel with production
-    database operations.  (Commands such as <command>SELECT</command>,
-    <command>INSERT</command>, <command>UPDATE</command>, and
-    <command>DELETE</command> will continue to function normally, though you
-    will not be able to modify the definition of a table with commands such as
-    <command>ALTER TABLE</command> while it is being vacuumed.)
-    <command>VACUUM FULL</command> requires an
-    <literal>ACCESS EXCLUSIVE</literal> lock on the table it is
-    working on, and therefore cannot be done in parallel with other use
-    of the table.  Generally, therefore,
-    administrators should strive to use standard <command>VACUUM</command> and
-    avoid <command>VACUUM FULL</command>.
-   </para>
-
-   <para>
-    <command>VACUUM</command> creates a substantial amount of I/O
-    traffic, which can cause poor performance for other active sessions.
-    There are configuration parameters that can be adjusted to reduce the
-    performance impact of background vacuuming &mdash; see
-    <xref linkend="runtime-config-resource-vacuum-cost"/>.
-   </para>
-  </sect2>
+  <para>
+   <command>VACUUM</command> creates a substantial amount of I/O
+   traffic, which can cause poor performance for other active sessions.
+   There are configuration parameters that can be adjusted to reduce the
+   performance impact of background vacuuming &mdash; see
+   <xref linkend="runtime-config-resource-vacuum-cost"/>.
+  </para>
 
   <sect2 id="vacuum-for-space-recovery">
    <title>Recovering Disk Space</title>
-- 
2.40.0



  [application/octet-stream] v1-0007-Make-maintenance.sgml-more-autovacuum-orientated.patch (7.4K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/6-v1-0007-Make-maintenance.sgml-more-autovacuum-orientated.patch)
  download | inline diff:
From 9c0a390d63d262fc7b72f32f1be0d088496b8168 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 12:11:10 -0700
Subject: [PATCH v1 7/9] Make maintenance.sgml more autovacuum-orientated.

Now that it's no longer in its own sect2, shorten the "Vacuuming basics"
content, and make it more autovacuum-orientated.  This gives much less
prominence to VACUUM FULL, which has little place in a section about
autovacuum.  We no longer define avoiding the need to run VACUUM FULL as
the purpose of vacuuming.

A later commit that overhauls "Recovering Disk Space" will add back a
passing mention of things like VACUUM FULL and TRUNCATE, but only as
something that might be relevant in extreme cases.  (Use of these
commands is hopefully neither "Routine" nor "Basic" to most users).
---
 doc/src/sgml/maintenance.sgml | 91 +++++++++++++++++------------------
 1 file changed, 44 insertions(+), 47 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 2e18a078a..7476e5922 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -32,11 +32,12 @@
  </para>
 
  <para>
-  The other main category of maintenance task is periodic <quote>vacuuming</quote>
-  of the database.  This activity is discussed in
-  <xref linkend="routine-vacuuming"/>.  Closely related to this is updating
-  the statistics that will be used by the query planner, as discussed in
-  <xref linkend="vacuum-for-statistics"/>.
+  The other main category of maintenance task is periodic
+  <quote><link linkend="routine-vacuuming">vacuuming</link></quote> of
+  the database by autovacuum.  Configuring autovacuum scheduling is
+  discussed in <xref linkend="autovacuum"/>.  Autovacuum also updates
+  the statistics that will be used by the query planner, as discussed
+  in <xref linkend="vacuum-for-statistics"/>.
  </para>
 
  <para>
@@ -244,7 +245,7 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
  </sect1>
 
  <sect1 id="routine-vacuuming">
-  <title>Routine Vacuuming</title>
+  <title>Autovacuum Maintenance Tasks</title>
 
   <indexterm zone="routine-vacuuming">
    <primary>vacuum</primary>
@@ -252,24 +253,20 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
 
   <para>
    <productname>PostgreSQL</productname> databases require periodic
-   maintenance known as <firstterm>vacuuming</firstterm>.  For many installations, it
-   is sufficient to let vacuuming be performed by the <firstterm>autovacuum
-   daemon</firstterm>, which is described in <xref linkend="autovacuum"/>.  You might
-   need to adjust the autovacuuming parameters described there to obtain best
-   results for your situation.  Some database administrators will want to
-   supplement or replace the daemon's activities with manually-managed
-   <command>VACUUM</command> commands, which typically are executed according to a
-   schedule by <application>cron</application> or <application>Task
-   Scheduler</application> scripts.  To set up manually-managed vacuuming properly,
-   it is essential to understand the issues discussed in the next few
-   subsections.  Administrators who rely on autovacuuming may still wish
-   to skim this material to help them understand and adjust autovacuuming.
+   maintenance known as <firstterm>vacuuming</firstterm>, and require
+   periodic updates to the statistics used by the
+   <productname>PostgreSQL</productname> query planner.  These
+   maintenance tasks are performed by the <link
+    linkend="sql-vacuum"><command>VACUUM</command></link> and <link
+    linkend="sql-analyze"><command>ANALYZE</command></link> commands
+   respectively.  For most installations, it is sufficient to let the
+   <firstterm>autovacuum daemon</firstterm> determine when to perform
+   these maintenance tasks (which is partly determined by configurable
+   table-level thresholds; see <xref linkend="autovacuum"/>).
   </para>
-
   <para>
-   <productname>PostgreSQL</productname>'s
-   <link linkend="sql-vacuum"><command>VACUUM</command></link> command has to
-   process each table on a regular basis for several reasons:
+   The autovacuum daemon has to process each table on a regular basis
+   for several reasons:
 
    <orderedlist>
     <listitem>
@@ -295,35 +292,35 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
     </listitem>
    </orderedlist>
 
-   Each of these reasons dictates performing <command>VACUUM</command> operations
-   of varying frequency and scope, as explained in the following subsections.
+   Maintenance work within the scope of items 1, 2, 3, and 4 is
+   performed by the <command>VACUUM</command> command internally.
+   Item 5 (maintenance of planner statistics) is handled by the
+   <command>ANALYZE</command> command internally.  Although this
+   section presents information about autovacuum, there is no
+   difference between manually-issued <command>VACUUM</command> and
+   <command>ANALYZE</command> commands and those run by the autovacuum
+   daemon (though there are autovacuum-specific variants of a small
+   number of settings that control <command>VACUUM</command>).
   </para>
-
   <para>
-   There are two variants of <command>VACUUM</command>: standard <command>VACUUM</command>
-   and <command>VACUUM FULL</command>.  <command>VACUUM FULL</command> can reclaim more
-   disk space but runs much more slowly.  Also,
-   the standard form of <command>VACUUM</command> can run in parallel with production
-   database operations.  (Commands such as <command>SELECT</command>,
-   <command>INSERT</command>, <command>UPDATE</command>, and
-   <command>DELETE</command> will continue to function normally, though you
-   will not be able to modify the definition of a table with commands such as
-   <command>ALTER TABLE</command> while it is being vacuumed.)
-   <command>VACUUM FULL</command> requires an
-   <literal>ACCESS EXCLUSIVE</literal> lock on the table it is
-   working on, and therefore cannot be done in parallel with other use
-   of the table.  Generally, therefore,
-   administrators should strive to use standard <command>VACUUM</command> and
-   avoid <command>VACUUM FULL</command>.
-  </para>
-
-  <para>
-   <command>VACUUM</command> creates a substantial amount of I/O
-   traffic, which can cause poor performance for other active sessions.
-   There are configuration parameters that can be adjusted to reduce the
-   performance impact of background vacuuming &mdash; see
+   Autovacuum creates a substantial amount of I/O traffic, which can
+   cause poor performance for other active sessions.  There are
+   configuration parameters that can be adjusted to reduce the
+   performance impact of background vacuuming.  See the
+   autovacuum-specific cost delay settings described in
+   <xref linkend="runtime-config-autovacuum"/>, and additional cost
+   delay settings described in
    <xref linkend="runtime-config-resource-vacuum-cost"/>.
   </para>
+  <para>
+   Some database administrators will want to supplement the daemon's
+   activities with manually-managed <command>VACUUM</command>
+   commands, which typically are executed according to a schedule by
+   <application>cron</application> or <application>Task
+    Scheduler</application> scripts.  It can be useful to perform
+   off-hours <command>VACUUM</command> commands during periods where
+   reduced load is expected.
+  </para>
 
   <sect2 id="vacuum-for-space-recovery">
    <title>Recovering Disk Space</title>
-- 
2.40.0



  [application/octet-stream] v1-0003-Normalize-maintenance.sgml-indentation.patch (4.7K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/7-v1-0003-Normalize-maintenance.sgml-indentation.patch)
  download | inline diff:
From 0bcfd65226d42f844455eb3e5ca7a3b5b6f61b5e Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 15:20:13 -0700
Subject: [PATCH v1 3/9] Normalize maintenance.sgml indentation.

---
 doc/src/sgml/maintenance.sgml | 82 +++++++++++++++++------------------
 1 file changed, 41 insertions(+), 41 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 6a7ec7c1d..e8c8647cd 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -11,53 +11,53 @@
   <primary>routine maintenance</primary>
  </indexterm>
 
-  <para>
-   <productname>PostgreSQL</productname>, like any database software, requires that certain tasks
-   be performed regularly to achieve optimum performance. The tasks
-   discussed here are <emphasis>required</emphasis>, but they
-   are repetitive in nature and can easily be automated using standard
-   tools such as <application>cron</application> scripts or
-   Windows' <application>Task Scheduler</application>.  It is the database
-   administrator's responsibility to set up appropriate scripts, and to
-   check that they execute successfully.
-  </para>
+ <para>
+  <productname>PostgreSQL</productname>, like any database software, requires that certain tasks
+  be performed regularly to achieve optimum performance. The tasks
+  discussed here are <emphasis>required</emphasis>, but they
+  are repetitive in nature and can easily be automated using standard
+  tools such as <application>cron</application> scripts or
+  Windows' <application>Task Scheduler</application>.  It is the database
+  administrator's responsibility to set up appropriate scripts, and to
+  check that they execute successfully.
+ </para>
 
-  <para>
-   One obvious maintenance task is the creation of backup copies of the data on a
-   regular schedule.  Without a recent backup, you have no chance of recovery
-   after a catastrophe (disk failure, fire, mistakenly dropping a critical
-   table, etc.).  The backup and recovery mechanisms available in
-   <productname>PostgreSQL</productname> are discussed at length in
-   <xref linkend="backup"/>.
-  </para>
+ <para>
+  One obvious maintenance task is the creation of backup copies of the data on a
+  regular schedule.  Without a recent backup, you have no chance of recovery
+  after a catastrophe (disk failure, fire, mistakenly dropping a critical
+  table, etc.).  The backup and recovery mechanisms available in
+  <productname>PostgreSQL</productname> are discussed at length in
+  <xref linkend="backup"/>.
+ </para>
 
-  <para>
-   The other main category of maintenance task is periodic <quote>vacuuming</quote>
-   of the database.  This activity is discussed in
-   <xref linkend="routine-vacuuming"/>.  Closely related to this is updating
-   the statistics that will be used by the query planner, as discussed in
-   <xref linkend="vacuum-for-statistics"/>.
-  </para>
+ <para>
+  The other main category of maintenance task is periodic <quote>vacuuming</quote>
+  of the database.  This activity is discussed in
+  <xref linkend="routine-vacuuming"/>.  Closely related to this is updating
+  the statistics that will be used by the query planner, as discussed in
+  <xref linkend="vacuum-for-statistics"/>.
+ </para>
 
-  <para>
-   Another task that might need periodic attention is log file management.
-   This is discussed in <xref linkend="logfile-maintenance"/>.
-  </para>
+ <para>
+  Another task that might need periodic attention is log file management.
+  This is discussed in <xref linkend="logfile-maintenance"/>.
+ </para>
 
-  <para>
-   <ulink
+ <para>
+  <ulink
    url="https://bucardo.org/check_postgres/"><application>check_postgres</application></ulink>
-   is available for monitoring database health and reporting unusual
-   conditions.  <application>check_postgres</application> integrates with
-   Nagios and MRTG, but can be run standalone too.
-  </para>
+  is available for monitoring database health and reporting unusual
+  conditions.  <application>check_postgres</application> integrates with
+  Nagios and MRTG, but can be run standalone too.
+ </para>
 
-  <para>
-   <productname>PostgreSQL</productname> is low-maintenance compared
-   to some other database management systems.  Nonetheless,
-   appropriate attention to these tasks will go far towards ensuring a
-   pleasant and productive experience with the system.
-  </para>
+ <para>
+  <productname>PostgreSQL</productname> is low-maintenance compared
+  to some other database management systems.  Nonetheless,
+  appropriate attention to these tasks will go far towards ensuring a
+  pleasant and productive experience with the system.
+ </para>
 
  <sect1 id="autovacuum">
   <title>The Autovacuum Daemon</title>
-- 
2.40.0



  [application/octet-stream] v1-0004-Reorder-routine-vacuuming-sections.patch (16.4K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/8-v1-0004-Reorder-routine-vacuuming-sections.patch)
  download | inline diff:
From 6522640d8378b1c8d37631e0cdf44ce4ad394f1f Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 11:19:50 -0700
Subject: [PATCH v1 4/9] Reorder routine vacuuming sections.

This doesn't change any of the content itself.  It is a mechanical
change.  The new order flows better because it talks about freezing
directly after talking about space recovery tasks.

Old order:

<sect2 id="vacuum-basics">
<sect2 id="vacuum-for-space-recovery">
<sect2 id="vacuum-for-statistics">
<sect2 id="vacuum-for-visibility-map">
<sect2 id="vacuum-for-wraparound">

New order:

<sect2 id="vacuum-basics">
<sect2 id="vacuum-for-space-recovery">
<sect2 id="vacuum-for-wraparound">
<sect2 id="vacuum-for-visibility-map">
<sect2 id="vacuum-for-statistics">

The new order matches processing order inside vacuumlazy.c.  This order
will be easier to work with in two later commits that more or less
rewrite "vacuum-for-wraparound" and "vacuum-for-space-recovery".
(Though it doesn't seem to make the existing content any less meaningful
without the later rewrite commits.)
---
 doc/src/sgml/maintenance.sgml | 306 +++++++++++++++++-----------------
 1 file changed, 155 insertions(+), 151 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index e8c8647cd..62e22d861 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -281,8 +281,9 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
      </listitem>
 
      <listitem>
-      <simpara>To update data statistics used by the
-      <productname>PostgreSQL</productname> query planner.</simpara>
+      <simpara>To protect against loss of very old data due to
+      <firstterm>transaction ID wraparound</firstterm> or
+      <firstterm>multixact ID wraparound</firstterm>.</simpara>
      </listitem>
 
      <listitem>
@@ -292,9 +293,8 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
      </listitem>
 
      <listitem>
-      <simpara>To protect against loss of very old data due to
-      <firstterm>transaction ID wraparound</firstterm> or
-      <firstterm>multixact ID wraparound</firstterm>.</simpara>
+      <simpara>To update data statistics used by the
+      <productname>PostgreSQL</productname> query planner.</simpara>
      </listitem>
     </orderedlist>
 
@@ -439,151 +439,6 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    </tip>
   </sect2>
 
-  <sect2 id="vacuum-for-statistics">
-   <title>Updating Planner Statistics</title>
-
-   <indexterm zone="vacuum-for-statistics">
-    <primary>statistics</primary>
-    <secondary>of the planner</secondary>
-   </indexterm>
-
-   <indexterm zone="vacuum-for-statistics">
-    <primary>ANALYZE</primary>
-   </indexterm>
-
-   <para>
-    The <productname>PostgreSQL</productname> query planner relies on
-    statistical information about the contents of tables in order to
-    generate good plans for queries.  These statistics are gathered by
-    the <link linkend="sql-analyze"><command>ANALYZE</command></link> command,
-    which can be invoked by itself or
-    as an optional step in <command>VACUUM</command>.  It is important to have
-    reasonably accurate statistics, otherwise poor choices of plans might
-    degrade database performance.
-   </para>
-
-   <para>
-    The autovacuum daemon, if enabled, will automatically issue
-    <command>ANALYZE</command> commands whenever the content of a table has
-    changed sufficiently.  However, administrators might prefer to rely
-    on manually-scheduled <command>ANALYZE</command> operations, particularly
-    if it is known that update activity on a table will not affect the
-    statistics of <quote>interesting</quote> columns.  The daemon schedules
-    <command>ANALYZE</command> strictly as a function of the number of rows
-    inserted or updated; it has no knowledge of whether that will lead
-    to meaningful statistical changes.
-   </para>
-
-   <para>
-    Tuples changed in partitions and inheritance children do not trigger
-    analyze on the parent table.  If the parent table is empty or rarely
-    changed, it may never be processed by autovacuum, and the statistics for
-    the inheritance tree as a whole won't be collected. It is necessary to
-    run <command>ANALYZE</command> on the parent table manually in order to
-    keep the statistics up to date.
-   </para>
-
-   <para>
-    As with vacuuming for space recovery, frequent updates of statistics
-    are more useful for heavily-updated tables than for seldom-updated
-    ones. But even for a heavily-updated table, there might be no need for
-    statistics updates if the statistical distribution of the data is
-    not changing much. A simple rule of thumb is to think about how much
-    the minimum and maximum values of the columns in the table change.
-    For example, a <type>timestamp</type> column that contains the time
-    of row update will have a constantly-increasing maximum value as
-    rows are added and updated; such a column will probably need more
-    frequent statistics updates than, say, a column containing URLs for
-    pages accessed on a website. The URL column might receive changes just
-    as often, but the statistical distribution of its values probably
-    changes relatively slowly.
-   </para>
-
-   <para>
-    It is possible to run <command>ANALYZE</command> on specific tables and even
-    just specific columns of a table, so the flexibility exists to update some
-    statistics more frequently than others if your application requires it.
-    In practice, however, it is usually best to just analyze the entire
-    database, because it is a fast operation.  <command>ANALYZE</command> uses a
-    statistically random sampling of the rows of a table rather than reading
-    every single row.
-   </para>
-
-   <tip>
-    <para>
-     Although per-column tweaking of <command>ANALYZE</command> frequency might not be
-     very productive, you might find it worthwhile to do per-column
-     adjustment of the level of detail of the statistics collected by
-     <command>ANALYZE</command>.  Columns that are heavily used in <literal>WHERE</literal>
-     clauses and have highly irregular data distributions might require a
-     finer-grain data histogram than other columns.  See <command>ALTER TABLE
-     SET STATISTICS</command>, or change the database-wide default using the <xref
-     linkend="guc-default-statistics-target"/> configuration parameter.
-    </para>
-
-    <para>
-     Also, by default there is limited information available about
-     the selectivity of functions.  However, if you create a statistics
-     object or an expression
-     index that uses a function call, useful statistics will be
-     gathered about the function, which can greatly improve query
-     plans that use the expression index.
-    </para>
-   </tip>
-
-   <tip>
-    <para>
-     The autovacuum daemon does not issue <command>ANALYZE</command> commands for
-     foreign tables, since it has no means of determining how often that
-     might be useful.  If your queries require statistics on foreign tables
-     for proper planning, it's a good idea to run manually-managed
-     <command>ANALYZE</command> commands on those tables on a suitable schedule.
-    </para>
-   </tip>
-
-   <tip>
-    <para>
-     The autovacuum daemon does not issue <command>ANALYZE</command> commands
-     for partitioned tables.  Inheritance parents will only be analyzed if the
-     parent itself is changed - changes to child tables do not trigger
-     autoanalyze on the parent table.  If your queries require statistics on
-     parent tables for proper planning, it is necessary to periodically run
-     a manual <command>ANALYZE</command> on those tables to keep the statistics
-     up to date.
-    </para>
-   </tip>
-
-  </sect2>
-
-  <sect2 id="vacuum-for-visibility-map">
-   <title>Updating the Visibility Map</title>
-
-   <para>
-    Vacuum maintains a <link linkend="storage-vm">visibility map</link> for each
-    table to keep track of which pages contain only tuples that are known to be
-    visible to all active transactions (and all future transactions, until the
-    page is again modified).  This has two purposes.  First, vacuum
-    itself can skip such pages on the next run, since there is nothing to
-    clean up.
-   </para>
-
-   <para>
-    Second, it allows <productname>PostgreSQL</productname> to answer some
-    queries using only the index, without reference to the underlying table.
-    Since <productname>PostgreSQL</productname> indexes don't contain tuple
-    visibility information, a normal index scan fetches the heap tuple for each
-    matching index entry, to check whether it should be seen by the current
-    transaction.
-    An <link linkend="indexes-index-only-scans"><firstterm>index-only
-    scan</firstterm></link>, on the other hand, checks the visibility map first.
-    If it's known that all tuples on the page are
-    visible, the heap fetch can be skipped.  This is most useful on
-    large data sets where the visibility map can prevent disk accesses.
-    The visibility map is vastly smaller than the heap, so it can easily be
-    cached even when the heap is very large.
-   </para>
-  </sect2>
-
   <sect2 id="vacuum-for-wraparound">
    <title>Preventing Transaction ID Wraparound Failures</title>
 
@@ -933,7 +788,156 @@ HINT:  Stop the postmaster and vacuum that database in single-user mode.
     </para>
    </sect3>
   </sect2>
- </sect1>
+
+  <sect2 id="vacuum-for-visibility-map">
+   <title>Updating the Visibility Map</title>
+
+   <para>
+    Vacuum maintains a <link linkend="storage-vm">visibility
+     map</link> for each table to keep track of which pages contain
+    only tuples that are known to be visible to all active
+    transactions (and all future transactions, until the page is again
+    modified).  This has two purposes.  First, vacuum itself can skip
+    such pages on the next run, since there is nothing to clean up.
+    Even <command>VACUUM</command>s that use the <link
+     linkend="aggressive-strategy">aggressive strategy</link> can skip
+    pages that are both all-visible and all-frozen (the visibility map
+    keeps track of which pages are all-frozen separately).
+   </para>
+
+   <para>
+    Second, it allows <productname>PostgreSQL</productname> to answer
+    some queries using only the index, without reference to the
+    underlying table.  Since <productname>PostgreSQL</productname>
+    indexes don't contain tuple visibility information, a normal index
+    scan fetches the heap tuple for each matching index entry, to
+    check whether it should be seen by the current transaction.  An
+    <link linkend="indexes-index-only-scans"><firstterm>index-only
+      scan</firstterm></link>, on the other hand, checks the
+    visibility map first.  If it's known that all tuples on the page
+    are visible, the heap fetch can be skipped.  This is most useful
+    on large data sets where the visibility map can prevent disk
+    accesses.  The visibility map is vastly smaller than the heap, so
+    it can easily be cached even when the heap is very large.
+   </para>
+  </sect2>
+
+  <sect2 id="vacuum-for-statistics">
+   <title>Updating Planner Statistics</title>
+
+   <indexterm zone="vacuum-for-statistics">
+    <primary>statistics</primary>
+    <secondary>of the planner</secondary>
+   </indexterm>
+
+   <indexterm zone="vacuum-for-statistics">
+    <primary>ANALYZE</primary>
+   </indexterm>
+
+   <para>
+    The <productname>PostgreSQL</productname> query planner relies on
+    statistical information about the contents of tables in order to
+    generate good plans for queries.  These statistics are gathered by
+    the <link linkend="sql-analyze"><command>ANALYZE</command></link> command,
+    which can be invoked by itself or
+    as an optional step in <command>VACUUM</command>.  It is important to have
+    reasonably accurate statistics, otherwise poor choices of plans might
+    degrade database performance.
+   </para>
+
+   <para>
+    The autovacuum daemon, if enabled, will automatically issue
+    <command>ANALYZE</command> commands whenever the content of a table has
+    changed sufficiently.  However, administrators might prefer to rely
+    on manually-scheduled <command>ANALYZE</command> operations, particularly
+    if it is known that update activity on a table will not affect the
+    statistics of <quote>interesting</quote> columns.  The daemon schedules
+    <command>ANALYZE</command> strictly as a function of the number of rows
+    inserted or updated; it has no knowledge of whether that will lead
+    to meaningful statistical changes.
+   </para>
+
+   <para>
+    Tuples changed in partitions and inheritance children do not trigger
+    analyze on the parent table.  If the parent table is empty or rarely
+    changed, it may never be processed by autovacuum, and the statistics for
+    the inheritance tree as a whole won't be collected. It is necessary to
+    run <command>ANALYZE</command> on the parent table manually in order to
+    keep the statistics up to date.
+   </para>
+
+   <para>
+    As with vacuuming for space recovery, frequent updates of statistics
+    are more useful for heavily-updated tables than for seldom-updated
+    ones. But even for a heavily-updated table, there might be no need for
+    statistics updates if the statistical distribution of the data is
+    not changing much. A simple rule of thumb is to think about how much
+    the minimum and maximum values of the columns in the table change.
+    For example, a <type>timestamp</type> column that contains the time
+    of row update will have a constantly-increasing maximum value as
+    rows are added and updated; such a column will probably need more
+    frequent statistics updates than, say, a column containing URLs for
+    pages accessed on a website. The URL column might receive changes just
+    as often, but the statistical distribution of its values probably
+    changes relatively slowly.
+   </para>
+
+   <para>
+    It is possible to run <command>ANALYZE</command> on specific tables and even
+    just specific columns of a table, so the flexibility exists to update some
+    statistics more frequently than others if your application requires it.
+    In practice, however, it is usually best to just analyze the entire
+    database, because it is a fast operation.  <command>ANALYZE</command> uses a
+    statistically random sampling of the rows of a table rather than reading
+    every single row.
+   </para>
+
+   <tip>
+    <para>
+     Although per-column tweaking of <command>ANALYZE</command> frequency might not be
+     very productive, you might find it worthwhile to do per-column
+     adjustment of the level of detail of the statistics collected by
+     <command>ANALYZE</command>.  Columns that are heavily used in <literal>WHERE</literal>
+     clauses and have highly irregular data distributions might require a
+     finer-grain data histogram than other columns.  See <command>ALTER TABLE
+      SET STATISTICS</command>, or change the database-wide default using the <xref
+      linkend="guc-default-statistics-target"/> configuration parameter.
+    </para>
+
+    <para>
+     Also, by default there is limited information available about
+     the selectivity of functions.  However, if you create a statistics
+     object or an expression
+     index that uses a function call, useful statistics will be
+     gathered about the function, which can greatly improve query
+     plans that use the expression index.
+    </para>
+   </tip>
+
+   <tip>
+    <para>
+     The autovacuum daemon does not issue <command>ANALYZE</command> commands for
+     foreign tables, since it has no means of determining how often that
+     might be useful.  If your queries require statistics on foreign tables
+     for proper planning, it's a good idea to run manually-managed
+     <command>ANALYZE</command> commands on those tables on a suitable schedule.
+    </para>
+   </tip>
+
+   <tip>
+    <para>
+     The autovacuum daemon does not issue <command>ANALYZE</command> commands
+     for partitioned tables.  Inheritance parents will only be analyzed if the
+     parent itself is changed - changes to child tables do not trigger
+     autoanalyze on the parent table.  If your queries require statistics on
+     parent tables for proper planning, it is necessary to periodically run
+     a manual <command>ANALYZE</command> on those tables to keep the statistics
+     up to date.
+    </para>
+   </tip>
+
+  </sect2>
+</sect1>
 
 
  <sect1 id="routine-reindex">
-- 
2.40.0



  [application/octet-stream] v1-0002-Restructure-autuovacuum-daemon-section.patch (5.3K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/9-v1-0002-Restructure-autuovacuum-daemon-section.patch)
  download | inline diff:
From 7ee4d3ab59559c3b31f9408623e9ad5d59514aaa Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Mon, 24 Apr 2023 09:21:01 -0700
Subject: [PATCH v1 2/9] Restructure autuovacuum daemon section.

Add sect2/sect3 subsections to autovacuum sect1.  Also reorder the
content slightly for clarity.

TODO Add some basic explanations of vacuuming and relfrozenxid
advancement, since that now appears later on in the chapter.
Alternatively, move the autovacuum daemon sect1 after the routine
vacuuming sect1.
---
 doc/src/sgml/maintenance.sgml | 66 ++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 24 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index a6295c399..6a7ec7c1d 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -100,6 +100,8 @@
    autovacuum workers' activity.
   </para>
 
+  <sect2 id="autovacuum-scheduling">
+   <title>Autovacuum Scheduling</title>
   <para>
    If several large tables all become eligible for vacuuming in a short
    amount of time, all autovacuum workers might become occupied with
@@ -112,6 +114,8 @@
    <xref linkend="guc-superuser-reserved-connections"/> limits.
   </para>
 
+  <sect3 id="autovacuum-vacuum-thresholds">
+   <title>Configurable thresholds for vacuuming</title>
   <para>
    Tables whose <structfield>relfrozenxid</structfield> value is more than
    <xref linkend="guc-autovacuum-freeze-max-age"/> transactions old are always
@@ -159,7 +163,10 @@ vacuum insert threshold = vacuum base insert threshold + vacuum insert scale fac
    <structfield>relfrozenxid</structfield>; otherwise, only pages that have been modified
    since the last vacuum are scanned.
   </para>
+ </sect3>
 
+  <sect3 id="autovacuum-analyze-thresholds">
+   <title>Configurable thresholds for <command>ANALYZE</command></title>
   <para>
    For analyze, a similar condition is used: the threshold, defined as:
 <programlisting>
@@ -168,20 +175,6 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    is compared to the total number of tuples inserted, updated, or deleted
    since the last <command>ANALYZE</command>.
   </para>
-
-  <para>
-   Partitioned tables are not processed by autovacuum.  Statistics
-   should be collected by running a manual <command>ANALYZE</command> when it is
-   first populated, and again whenever the distribution of data in its
-   partitions changes significantly.
-  </para>
-
-  <para>
-   Temporary tables cannot be accessed by autovacuum.  Therefore,
-   appropriate vacuum and analyze operations should be performed via
-   session SQL commands.
-  </para>
-
   <para>
    The default thresholds and scale factors are taken from
    <filename>postgresql.conf</filename>, but it is possible to override them
@@ -192,18 +185,25 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
    used. See <xref linkend="runtime-config-autovacuum"/> for more details on
    the global settings.
   </para>
+  </sect3>
+  </sect2>
 
-  <para>
-   When multiple workers are running, the autovacuum cost delay parameters
-   (see <xref linkend="runtime-config-resource-vacuum-cost"/>) are
-   <quote>balanced</quote> among all the running workers, so that the
-   total I/O impact on the system is the same regardless of the number
-   of workers actually running.  However, any workers processing tables whose
-   per-table <literal>autovacuum_vacuum_cost_delay</literal> or
-   <literal>autovacuum_vacuum_cost_limit</literal> storage parameters have been set
-   are not considered in the balancing algorithm.
-  </para>
+  <sect2 id="autovacuum-cost-delays">
+   <title>Autovacuum Cost-based Delays</title>
+   <para>
+    When multiple workers are running, the autovacuum cost delay parameters
+    (see <xref linkend="runtime-config-resource-vacuum-cost"/>) are
+    <quote>balanced</quote> among all the running workers, so that the
+    total I/O impact on the system is the same regardless of the number
+    of workers actually running.  However, any workers processing tables whose
+    per-table <literal>autovacuum_vacuum_cost_delay</literal> or
+    <literal>autovacuum_vacuum_cost_limit</literal> storage parameters have been set
+    are not considered in the balancing algorithm.
+   </para>
+  </sect2>
 
+  <sect2 id="autovacuum-lock-conflicts">
+   <title>Autovacuum and Lock Conflicts</title>
   <para>
    Autovacuum workers generally don't block other commands.  If a process
    attempts to acquire a lock that conflicts with the
@@ -223,6 +223,24 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
     effectively prevent autovacuums from ever completing.
    </para>
   </warning>
+  </sect2>
+
+  <sect2 id="autovacuum-limitations">
+   <title>Limitations</title>
+  <para>
+   Partitioned tables are not processed by autovacuum.  Statistics
+   should be collected by running a manual <command>ANALYZE</command> when it is
+   first populated, and again whenever the distribution of data in its
+   partitions changes significantly.
+  </para>
+
+  <para>
+   Temporary tables cannot be accessed by autovacuum.  Therefore,
+   appropriate vacuum and analyze operations should be performed via
+   session SQL commands.
+  </para>
+  </sect2>
+
  </sect1>
 
  <sect1 id="routine-vacuuming">
-- 
2.40.0



  [application/octet-stream] v1-0005-Move-Interpreting-XID-stamps-from-tuple-headers.patch (9.3K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/10-v1-0005-Move-Interpreting-XID-stamps-from-tuple-headers.patch)
  download | inline diff:
From a66f93e6bc90bd95e77b2fa923d8c6151e834bb0 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Sat, 22 Apr 2023 12:41:00 -0700
Subject: [PATCH v1 5/9] Move Interpreting XID stamps from tuple headers.

This is intended to be fairly close to a mechanical change.  It isn't
entirely mechanical, though, since the original wording has been
slightly modified for it to work in context.

Structuring things this way should make life a little easier for doc
translators.
---
 doc/src/sgml/maintenance.sgml | 81 +++++++----------------------------
 doc/src/sgml/storage.sgml     | 62 +++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 65 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 62e22d861..f554e12bf 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -447,75 +447,26 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
     <secondary>wraparound</secondary>
    </indexterm>
 
-    <indexterm>
-     <primary>wraparound</primary>
-     <secondary>of transaction IDs</secondary>
-    </indexterm>
+   <indexterm>
+    <primary>wraparound</primary>
+    <secondary>of transaction IDs</secondary>
+   </indexterm>
 
    <para>
-    <productname>PostgreSQL</productname>'s
-    <link linkend="mvcc-intro">MVCC</link> transaction semantics
-    depend on being able to compare transaction ID (<acronym>XID</acronym>)
-    numbers: a row version with an insertion XID greater than the current
-    transaction's XID is <quote>in the future</quote> and should not be visible
-    to the current transaction.  But since transaction IDs have limited size
-    (32 bits) a cluster that runs for a long time (more
-    than 4 billion transactions) would suffer <firstterm>transaction ID
-    wraparound</firstterm>: the XID counter wraps around to zero, and all of a sudden
-    transactions that were in the past appear to be in the future &mdash; which
-    means their output become invisible.  In short, catastrophic data loss.
-    (Actually the data is still there, but that's cold comfort if you cannot
-    get at it.)  To avoid this, it is necessary to vacuum every table
-    in every database at least once every two billion transactions.
+    <productname>PostgreSQL</productname>'s <link
+     linkend="mvcc-intro">MVCC</link> transaction semantics depend on
+    being able to compare <glossterm linkend="glossary-xid">transaction
+     ID numbers (<acronym>XID</acronym>)</glossterm> to determine
+    whether or not the row is visible to each query's MVCC snapshot
+    (see <link linkend="interpreting-xid-stamps">
+     interpreting XID stamps from tuple headers</link>).  But since
+    on-disk storage of transaction IDs in heap pages uses a truncated
+    32-bit representation to save space (rather than the full 64-bit
+    representation), it is necessary to vacuum every table in every
+    database <emphasis>at least</emphasis> once every two billion
+    transactions (though far more frequent vacuuming is typical).
    </para>
 
-   <para>
-    The reason that periodic vacuuming solves the problem is that
-    <command>VACUUM</command> will mark rows as <emphasis>frozen</emphasis>, indicating that
-    they were inserted by a transaction that committed sufficiently far in
-    the past that the effects of the inserting transaction are certain to be
-    visible to all current and future transactions.
-    Normal XIDs are
-    compared using modulo-2<superscript>32</superscript> arithmetic. This means
-    that for every normal XID, there are two billion XIDs that are
-    <quote>older</quote> and two billion that are <quote>newer</quote>; another
-    way to say it is that the normal XID space is circular with no
-    endpoint. Therefore, once a row version has been created with a particular
-    normal XID, the row version will appear to be <quote>in the past</quote> for
-    the next two billion transactions, no matter which normal XID we are
-    talking about. If the row version still exists after more than two billion
-    transactions, it will suddenly appear to be in the future. To
-    prevent this, <productname>PostgreSQL</productname> reserves a special XID,
-    <literal>FrozenTransactionId</literal>, which does not follow the normal XID
-    comparison rules and is always considered older
-    than every normal XID.
-    Frozen row versions are treated as if the inserting XID were
-    <literal>FrozenTransactionId</literal>, so that they will appear to be
-    <quote>in the past</quote> to all normal transactions regardless of wraparound
-    issues, and so such row versions will be valid until deleted, no matter
-    how long that is.
-   </para>
-
-   <note>
-    <para>
-     In <productname>PostgreSQL</productname> versions before 9.4, freezing was
-     implemented by actually replacing a row's insertion XID
-     with <literal>FrozenTransactionId</literal>, which was visible in the
-     row's <structname>xmin</structname> system column.  Newer versions just set a flag
-     bit, preserving the row's original <structname>xmin</structname> for possible
-     forensic use.  However, rows with <structname>xmin</structname> equal
-     to <literal>FrozenTransactionId</literal> (2) may still be found
-     in databases <application>pg_upgrade</application>'d from pre-9.4 versions.
-    </para>
-    <para>
-     Also, system catalogs may contain rows with <structname>xmin</structname> equal
-     to <literal>BootstrapTransactionId</literal> (1), indicating that they were
-     inserted during the first phase of <application>initdb</application>.
-     Like <literal>FrozenTransactionId</literal>, this special XID is treated as
-     older than every normal XID.
-    </para>
-   </note>
-
    <para>
     <xref linkend="guc-vacuum-freeze-min-age"/>
     controls how old an XID value has to be before rows bearing that XID will be
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index e5b9f3f1f..f31a002fc 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -1072,6 +1072,68 @@ data. Empty in ordinary tables.</entry>
   it might be compressed, too (see <xref linkend="storage-toast"/>).
 
  </para>
+
+ <sect3 id="interpreting-xid-stamps">
+  <title>Interpreting XID stamps from tuple headers</title>
+
+  <para>
+   The on-disk representation of transaction IDs (the representation
+   used in <structfield>t_xmin</structfield> and
+   <structfield>t_xmax</structfield> fields) use a truncated 32-bit
+   representation of transaction IDs, not the full 64-bit
+   representation.  This is not suitable for long term storage without
+   special processing by <command>VACUUM</command>.
+  </para>
+
+  <para>
+   <command>VACUUM</command> <link linkend="routine-vacuuming">will
+    mark tuple headers <emphasis>frozen</emphasis></link>, indicating
+   that all eligible rows on the page were inserted by a transaction
+   that committed sufficiently far in the past that the effects of the
+   inserting transaction are certain to be visible to all current and
+   future transactions.  Normal XIDs are compared using
+   modulo-2<superscript>32</superscript> arithmetic. This means that
+   for every normal XID, there are two billion XIDs that are
+   <quote>older</quote> and two billion that are <quote>newer</quote>;
+   another way to say it is that the normal XID space is circular with
+   no endpoint. Therefore, once a row version has been created with a
+   particular normal XID, the row version will appear to be <quote>in
+    the past</quote> for the next two billion transactions, no matter
+   which normal XID we are talking about. If the row version still
+   exists after more than two billion transactions, it will suddenly
+   appear to be in the future. To prevent this,
+   <productname>PostgreSQL</productname> reserves a special XID,
+   <literal>FrozenTransactionId</literal>, which does not follow the
+   normal XID comparison rules and is always considered older than
+   every normal XID.  Frozen row versions are treated as if the
+   inserting XID were <literal>FrozenTransactionId</literal>, so that
+   they will appear to be <quote>in the past</quote> to all normal
+   transactions regardless of wraparound issues, and so such row
+   versions will be valid until deleted, no matter how long that is.
+  </para>
+
+  <note>
+   <para>
+    In <productname>PostgreSQL</productname> versions before 9.4, freezing was
+    implemented by actually replacing a row's insertion XID
+    with <literal>FrozenTransactionId</literal>, which was visible in the
+    row's <structname>xmin</structname> system column.  Newer versions just set a flag
+    bit, preserving the row's original <structname>xmin</structname> for possible
+    forensic use.  However, rows with <structname>xmin</structname> equal
+    to <literal>FrozenTransactionId</literal> (2) may still be found
+    in databases <application>pg_upgrade</application>'d from pre-9.4 versions.
+   </para>
+   <para>
+    Also, system catalogs may contain rows with <structname>xmin</structname> equal
+    to <literal>BootstrapTransactionId</literal> (1), indicating that they were
+    inserted during the first phase of <application>initdb</application>.
+    Like <literal>FrozenTransactionId</literal>, this special XID is treated as
+    older than every normal XID.
+   </para>
+  </note>
+
+</sect3>
+
  </sect2>
 </sect1>
 
-- 
2.40.0



  [application/octet-stream] v1-0001-Make-autovacuum-docs-into-a-sect1-of-its-own.patch (17.3K, ../../CAH2-Wzm_vCegKSwUOG2H7368=E8yuF4+mAxaK4RDj=+2_Puzmg@mail.gmail.com/11-v1-0001-Make-autovacuum-docs-into-a-sect1-of-its-own.patch)
  download | inline diff:
From 19f968d5302d25af67517a8d1bad8e961e11af6a Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <[email protected]>
Date: Wed, 12 Apr 2023 14:42:06 -0700
Subject: [PATCH v1 1/9] Make autovacuum docs into a sect1 of its own.

This doesn't change any of the content itself.
---
 doc/src/sgml/maintenance.sgml | 332 +++++++++++++++++-----------------
 1 file changed, 166 insertions(+), 166 deletions(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 9cf9d030a..a6295c399 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -59,6 +59,172 @@
    pleasant and productive experience with the system.
   </para>
 
+ <sect1 id="autovacuum">
+  <title>The Autovacuum Daemon</title>
+
+  <indexterm>
+   <primary>autovacuum</primary>
+   <secondary>general information</secondary>
+  </indexterm>
+  <para>
+   <productname>PostgreSQL</productname> has an optional but highly
+   recommended feature called <firstterm>autovacuum</firstterm>,
+   whose purpose is to automate the execution of
+   <command>VACUUM</command> and <command>ANALYZE</command> commands.
+   When enabled, autovacuum checks for
+   tables that have had a large number of inserted, updated or deleted
+   tuples.  These checks use the statistics collection facility;
+   therefore, autovacuum cannot be used unless <xref
+    linkend="guc-track-counts"/> is set to <literal>true</literal>.
+   In the default configuration, autovacuuming is enabled and the related
+   configuration parameters are appropriately set.
+  </para>
+
+  <para>
+   The <quote>autovacuum daemon</quote> actually consists of multiple processes.
+   There is a persistent daemon process, called the
+   <firstterm>autovacuum launcher</firstterm>, which is in charge of starting
+   <firstterm>autovacuum worker</firstterm> processes for all databases. The
+   launcher will distribute the work across time, attempting to start one
+   worker within each database every <xref linkend="guc-autovacuum-naptime"/>
+   seconds.  (Therefore, if the installation has <replaceable>N</replaceable> databases,
+   a new worker will be launched every
+   <varname>autovacuum_naptime</varname>/<replaceable>N</replaceable> seconds.)
+   A maximum of <xref linkend="guc-autovacuum-max-workers"/> worker processes
+   are allowed to run at the same time. If there are more than
+   <varname>autovacuum_max_workers</varname> databases to be processed,
+   the next database will be processed as soon as the first worker finishes.
+   Each worker process will check each table within its database and
+   execute <command>VACUUM</command> and/or <command>ANALYZE</command> as needed.
+   <xref linkend="guc-log-autovacuum-min-duration"/> can be set to monitor
+   autovacuum workers' activity.
+  </para>
+
+  <para>
+   If several large tables all become eligible for vacuuming in a short
+   amount of time, all autovacuum workers might become occupied with
+   vacuuming those tables for a long period.  This would result
+   in other tables and databases not being vacuumed until a worker becomes
+   available. There is no limit on how many workers might be in a
+   single database, but workers do try to avoid repeating work that has
+   already been done by other workers. Note that the number of running
+   workers does not count towards <xref linkend="guc-max-connections"/> or
+   <xref linkend="guc-superuser-reserved-connections"/> limits.
+  </para>
+
+  <para>
+   Tables whose <structfield>relfrozenxid</structfield> value is more than
+   <xref linkend="guc-autovacuum-freeze-max-age"/> transactions old are always
+   vacuumed (this also applies to those tables whose freeze max age has
+   been modified via storage parameters; see below).  Otherwise, if the
+   number of tuples obsoleted since the last
+   <command>VACUUM</command> exceeds the <quote>vacuum threshold</quote>, the
+   table is vacuumed.  The vacuum threshold is defined as:
+<programlisting>
+vacuum threshold = vacuum base threshold + vacuum scale factor * number of tuples
+</programlisting>
+   where the vacuum base threshold is
+   <xref linkend="guc-autovacuum-vacuum-threshold"/>,
+   the vacuum scale factor is
+   <xref linkend="guc-autovacuum-vacuum-scale-factor"/>,
+   and the number of tuples is
+   <structname>pg_class</structname>.<structfield>reltuples</structfield>.
+  </para>
+
+  <para>
+   The table is also vacuumed if the number of tuples inserted since the last
+   vacuum has exceeded the defined insert threshold, which is defined as:
+<programlisting>
+vacuum insert threshold = vacuum base insert threshold + vacuum insert scale factor * number of tuples
+</programlisting>
+   where the vacuum insert base threshold is
+   <xref linkend="guc-autovacuum-vacuum-insert-threshold"/>,
+   and vacuum insert scale factor is
+   <xref linkend="guc-autovacuum-vacuum-insert-scale-factor"/>.
+   Such vacuums may allow portions of the table to be marked as
+   <firstterm>all visible</firstterm> and also allow tuples to be frozen, which
+   can reduce the work required in subsequent vacuums.
+   For tables which receive <command>INSERT</command> operations but no or
+   almost no <command>UPDATE</command>/<command>DELETE</command> operations,
+   it may be beneficial to lower the table's
+   <xref linkend="reloption-autovacuum-freeze-min-age"/> as this may allow
+   tuples to be frozen by earlier vacuums.  The number of obsolete tuples and
+   the number of inserted tuples are obtained from the cumulative statistics system;
+   it is a semi-accurate count updated by each <command>UPDATE</command>,
+   <command>DELETE</command> and <command>INSERT</command> operation.  (It is
+   only semi-accurate because some information might be lost under heavy
+   load.)  If the <structfield>relfrozenxid</structfield> value of the table
+   is more than <varname>vacuum_freeze_table_age</varname> transactions old,
+   an aggressive vacuum is performed to freeze old tuples and advance
+   <structfield>relfrozenxid</structfield>; otherwise, only pages that have been modified
+   since the last vacuum are scanned.
+  </para>
+
+  <para>
+   For analyze, a similar condition is used: the threshold, defined as:
+<programlisting>
+analyze threshold = analyze base threshold + analyze scale factor * number of tuples
+</programlisting>
+   is compared to the total number of tuples inserted, updated, or deleted
+   since the last <command>ANALYZE</command>.
+  </para>
+
+  <para>
+   Partitioned tables are not processed by autovacuum.  Statistics
+   should be collected by running a manual <command>ANALYZE</command> when it is
+   first populated, and again whenever the distribution of data in its
+   partitions changes significantly.
+  </para>
+
+  <para>
+   Temporary tables cannot be accessed by autovacuum.  Therefore,
+   appropriate vacuum and analyze operations should be performed via
+   session SQL commands.
+  </para>
+
+  <para>
+   The default thresholds and scale factors are taken from
+   <filename>postgresql.conf</filename>, but it is possible to override them
+   (and many other autovacuum control parameters) on a per-table basis; see
+   <xref linkend="sql-createtable-storage-parameters"/> for more information.
+   If a setting has been changed via a table's storage parameters, that value
+   is used when processing that table; otherwise the global settings are
+   used. See <xref linkend="runtime-config-autovacuum"/> for more details on
+   the global settings.
+  </para>
+
+  <para>
+   When multiple workers are running, the autovacuum cost delay parameters
+   (see <xref linkend="runtime-config-resource-vacuum-cost"/>) are
+   <quote>balanced</quote> among all the running workers, so that the
+   total I/O impact on the system is the same regardless of the number
+   of workers actually running.  However, any workers processing tables whose
+   per-table <literal>autovacuum_vacuum_cost_delay</literal> or
+   <literal>autovacuum_vacuum_cost_limit</literal> storage parameters have been set
+   are not considered in the balancing algorithm.
+  </para>
+
+  <para>
+   Autovacuum workers generally don't block other commands.  If a process
+   attempts to acquire a lock that conflicts with the
+   <literal>SHARE UPDATE EXCLUSIVE</literal> lock held by autovacuum, lock
+   acquisition will interrupt the autovacuum.  For conflicting lock modes,
+   see <xref linkend="table-lock-compatibility"/>.  However, if the autovacuum
+   is running to prevent transaction ID wraparound (i.e., the autovacuum query
+   name in the <structname>pg_stat_activity</structname> view ends with
+   <literal>(to prevent wraparound)</literal>), the autovacuum is not
+   automatically interrupted.
+  </para>
+
+  <warning>
+   <para>
+    Regularly running commands that acquire locks conflicting with a
+    <literal>SHARE UPDATE EXCLUSIVE</literal> lock (e.g., ANALYZE) can
+    effectively prevent autovacuums from ever completing.
+   </para>
+  </warning>
+ </sect1>
+
  <sect1 id="routine-vacuuming">
   <title>Routine Vacuuming</title>
 
@@ -749,172 +915,6 @@ HINT:  Stop the postmaster and vacuum that database in single-user mode.
     </para>
    </sect3>
   </sect2>
-
-  <sect2 id="autovacuum">
-   <title>The Autovacuum Daemon</title>
-
-   <indexterm>
-    <primary>autovacuum</primary>
-    <secondary>general information</secondary>
-   </indexterm>
-   <para>
-    <productname>PostgreSQL</productname> has an optional but highly
-    recommended feature called <firstterm>autovacuum</firstterm>,
-    whose purpose is to automate the execution of
-    <command>VACUUM</command> and <command>ANALYZE</command> commands.
-    When enabled, autovacuum checks for
-    tables that have had a large number of inserted, updated or deleted
-    tuples.  These checks use the statistics collection facility;
-    therefore, autovacuum cannot be used unless <xref
-    linkend="guc-track-counts"/> is set to <literal>true</literal>.
-    In the default configuration, autovacuuming is enabled and the related
-    configuration parameters are appropriately set.
-   </para>
-
-   <para>
-    The <quote>autovacuum daemon</quote> actually consists of multiple processes.
-    There is a persistent daemon process, called the
-    <firstterm>autovacuum launcher</firstterm>, which is in charge of starting
-    <firstterm>autovacuum worker</firstterm> processes for all databases. The
-    launcher will distribute the work across time, attempting to start one
-    worker within each database every <xref linkend="guc-autovacuum-naptime"/>
-    seconds.  (Therefore, if the installation has <replaceable>N</replaceable> databases,
-    a new worker will be launched every
-    <varname>autovacuum_naptime</varname>/<replaceable>N</replaceable> seconds.)
-    A maximum of <xref linkend="guc-autovacuum-max-workers"/> worker processes
-    are allowed to run at the same time. If there are more than
-    <varname>autovacuum_max_workers</varname> databases to be processed,
-    the next database will be processed as soon as the first worker finishes.
-    Each worker process will check each table within its database and
-    execute <command>VACUUM</command> and/or <command>ANALYZE</command> as needed.
-    <xref linkend="guc-log-autovacuum-min-duration"/> can be set to monitor
-    autovacuum workers' activity.
-   </para>
-
-   <para>
-    If several large tables all become eligible for vacuuming in a short
-    amount of time, all autovacuum workers might become occupied with
-    vacuuming those tables for a long period.  This would result
-    in other tables and databases not being vacuumed until a worker becomes
-    available. There is no limit on how many workers might be in a
-    single database, but workers do try to avoid repeating work that has
-    already been done by other workers. Note that the number of running
-    workers does not count towards <xref linkend="guc-max-connections"/> or
-    <xref linkend="guc-superuser-reserved-connections"/> limits.
-   </para>
-
-   <para>
-    Tables whose <structfield>relfrozenxid</structfield> value is more than
-    <xref linkend="guc-autovacuum-freeze-max-age"/> transactions old are always
-    vacuumed (this also applies to those tables whose freeze max age has
-    been modified via storage parameters; see below).  Otherwise, if the
-    number of tuples obsoleted since the last
-    <command>VACUUM</command> exceeds the <quote>vacuum threshold</quote>, the
-    table is vacuumed.  The vacuum threshold is defined as:
-<programlisting>
-vacuum threshold = vacuum base threshold + vacuum scale factor * number of tuples
-</programlisting>
-    where the vacuum base threshold is
-    <xref linkend="guc-autovacuum-vacuum-threshold"/>,
-    the vacuum scale factor is
-    <xref linkend="guc-autovacuum-vacuum-scale-factor"/>,
-    and the number of tuples is
-    <structname>pg_class</structname>.<structfield>reltuples</structfield>.
-   </para>
-
-   <para>
-    The table is also vacuumed if the number of tuples inserted since the last
-    vacuum has exceeded the defined insert threshold, which is defined as:
-<programlisting>
-vacuum insert threshold = vacuum base insert threshold + vacuum insert scale factor * number of tuples
-</programlisting>
-    where the vacuum insert base threshold is
-    <xref linkend="guc-autovacuum-vacuum-insert-threshold"/>,
-    and vacuum insert scale factor is
-    <xref linkend="guc-autovacuum-vacuum-insert-scale-factor"/>.
-    Such vacuums may allow portions of the table to be marked as
-    <firstterm>all visible</firstterm> and also allow tuples to be frozen, which
-    can reduce the work required in subsequent vacuums.
-    For tables which receive <command>INSERT</command> operations but no or
-    almost no <command>UPDATE</command>/<command>DELETE</command> operations,
-    it may be beneficial to lower the table's
-    <xref linkend="reloption-autovacuum-freeze-min-age"/> as this may allow
-    tuples to be frozen by earlier vacuums.  The number of obsolete tuples and
-    the number of inserted tuples are obtained from the cumulative statistics system;
-    it is a semi-accurate count updated by each <command>UPDATE</command>,
-    <command>DELETE</command> and <command>INSERT</command> operation.  (It is
-    only semi-accurate because some information might be lost under heavy
-    load.)  If the <structfield>relfrozenxid</structfield> value of the table
-    is more than <varname>vacuum_freeze_table_age</varname> transactions old,
-    an aggressive vacuum is performed to freeze old tuples and advance
-    <structfield>relfrozenxid</structfield>; otherwise, only pages that have been modified
-    since the last vacuum are scanned.
-   </para>
-
-   <para>
-    For analyze, a similar condition is used: the threshold, defined as:
-<programlisting>
-analyze threshold = analyze base threshold + analyze scale factor * number of tuples
-</programlisting>
-    is compared to the total number of tuples inserted, updated, or deleted
-    since the last <command>ANALYZE</command>.
-   </para>
-
-   <para>
-    Partitioned tables are not processed by autovacuum.  Statistics
-    should be collected by running a manual <command>ANALYZE</command> when it is
-    first populated, and again whenever the distribution of data in its
-    partitions changes significantly.
-   </para>
-
-   <para>
-    Temporary tables cannot be accessed by autovacuum.  Therefore,
-    appropriate vacuum and analyze operations should be performed via
-    session SQL commands.
-   </para>
-
-   <para>
-    The default thresholds and scale factors are taken from
-    <filename>postgresql.conf</filename>, but it is possible to override them
-    (and many other autovacuum control parameters) on a per-table basis; see
-    <xref linkend="sql-createtable-storage-parameters"/> for more information.
-    If a setting has been changed via a table's storage parameters, that value
-    is used when processing that table; otherwise the global settings are
-    used. See <xref linkend="runtime-config-autovacuum"/> for more details on
-    the global settings.
-   </para>
-
-   <para>
-    When multiple workers are running, the autovacuum cost delay parameters
-    (see <xref linkend="runtime-config-resource-vacuum-cost"/>) are
-    <quote>balanced</quote> among all the running workers, so that the
-    total I/O impact on the system is the same regardless of the number
-    of workers actually running.  However, any workers processing tables whose
-    per-table <literal>autovacuum_vacuum_cost_delay</literal> or
-    <literal>autovacuum_vacuum_cost_limit</literal> storage parameters have been set
-    are not considered in the balancing algorithm.
-   </para>
-
-   <para>
-    Autovacuum workers generally don't block other commands.  If a process
-    attempts to acquire a lock that conflicts with the
-    <literal>SHARE UPDATE EXCLUSIVE</literal> lock held by autovacuum, lock
-    acquisition will interrupt the autovacuum.  For conflicting lock modes,
-    see <xref linkend="table-lock-compatibility"/>.  However, if the autovacuum
-    is running to prevent transaction ID wraparound (i.e., the autovacuum query
-    name in the <structname>pg_stat_activity</structname> view ends with
-    <literal>(to prevent wraparound)</literal>), the autovacuum is not
-    automatically interrupted.
-   </para>
-
-   <warning>
-    <para>
-     Regularly running commands that acquire locks conflicting with a
-     <literal>SHARE UPDATE EXCLUSIVE</literal> lock (e.g., ANALYZE) can
-     effectively prevent autovacuums from ever completing.
-    </para>
-   </warning>
-  </sect2>
  </sect1>
 
 
-- 
2.40.0



^ permalink  raw  reply  [nested|flat] 47+ messages in thread

end of thread, other threads:[~2023-04-24 21:57 UTC | newest]

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-- links below jump to the message on this page --
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v3 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v6 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v9 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v8 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v8 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v5 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2020-07-14 00:15 [PATCH v1 1/2] Let ALTER TABLE exec routines deal with the relation Alvaro Herrera <[email protected]>
2023-04-24 21:57 Overhauling "Routine Vacuuming" docs, particularly its handling of freezing Peter Geoghegan <[email protected]>

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