COPY FREEZE and mark committed on fresh tables.

When a relfilenode is created in this subtransaction or
a committed child transaction and it cannot otherwise
be seen by our own process, mark tuples committed ahead
of transaction commit for all COPY commands in same
transaction. If FREEZE specified on COPY
and pre-conditions met then rows will also be frozen.
Both options designed to avoid revisiting rows after commit,
increasing performance of subsequent commands after
data load and upgrade. pg_restore changes later.

Simon Riggs, review comments from Heikki Linnakangas, Noah Misch and design
input from Tom Lane, Robert Haas and Kevin Grittner

10 files changed, 269 insertions, 1 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 4abbdb68468..b66e26bebff 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -1875,6 +1875,14 @@ FreeBulkInsertState(BulkInsertState bistate)
  * The HEAP_INSERT_SKIP_FSM option is passed directly to
  * RelationGetBufferForTuple, which see for more info.
  *
+ * HEAP_INSERT_COMMITTED should only be specified for inserts into
+ * relfilenodes created during the current subtransaction and when
+ * there are no prior snapshots or pre-existing portals open.
+ *
+ * HEAP_INSERT_FROZEN only has meaning when HEAP_INSERT_COMMITTED is
+ * also set. This causes rows to be frozen, which is an MVCC violation
+ * and requires explicit options chosen by user.
+ *
  * Note that these options will be applied when inserting into the heap's
  * TOAST table, too, if the tuple requires any out-of-line data.
  *
@@ -2078,7 +2086,14 @@ heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
 	tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
 	tup->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
 	tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
-	HeapTupleHeaderSetXmin(tup->t_data, xid);
+	if (options & HEAP_INSERT_COMMITTED)
+	{
+		tup->t_data->t_infomask |= HEAP_XMIN_COMMITTED;
+		if (options & HEAP_INSERT_FROZEN)
+			HeapTupleHeaderSetXmin(tup->t_data, FrozenTransactionId);
+	}
+	else
+		HeapTupleHeaderSetXmin(tup->t_data, xid);
 	HeapTupleHeaderSetCmin(tup->t_data, cid);
 	HeapTupleHeaderSetXmax(tup->t_data, 0);		/* for cleanliness */
 	tup->t_tableOid = RelationGetRelid(relation);
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 10c89c79b91..479c4cb17d6 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -44,6 +44,7 @@
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
+#include "utils/portal.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
 
@@ -109,6 +110,7 @@ typedef struct CopyStateData
 	char	   *filename;		/* filename, or NULL for STDIN/STDOUT */
 	bool		binary;			/* binary format? */
 	bool		oids;			/* include OIDs? */
+	bool		freeze;			/* freeze rows on loading? */
 	bool		csv_mode;		/* Comma Separated Value format? */
 	bool		header_line;	/* CSV header line? */
 	char	   *null_print;		/* NULL marker string (server encoding!) */
@@ -895,6 +897,14 @@ ProcessCopyOptions(CopyState cstate,
 						 errmsg("conflicting or redundant options")));
 			cstate->oids = defGetBoolean(defel);
 		}
+		else if (strcmp(defel->defname, "freeze") == 0)
+		{
+			if (cstate->freeze)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			cstate->freeze = defGetBoolean(defel);
+		}
 		else if (strcmp(defel->defname, "delimiter") == 0)
 		{
 			if (cstate->delim)
@@ -1974,8 +1984,31 @@ CopyFrom(CopyState cstate)
 		hi_options |= HEAP_INSERT_SKIP_FSM;
 		if (!XLogIsNeeded())
 			hi_options |= HEAP_INSERT_SKIP_WAL;
+
+		/*
+		 * Optimize if new relfilenode was created in this subxact or
+		 * one of its committed children and we won't see those rows later
+		 * as part of an earlier scan or command. This ensures that if this
+		 * subtransaction aborts then the frozen rows won't be visible
+		 * after xact cleanup. Note that the stronger test of exactly
+		 * which subtransaction created it is crucial for correctness
+		 * of this optimisation.
+		 */
+		if (ThereAreNoPriorRegisteredSnapshots() &&
+			ThereAreNoReadyPortals() &&
+			cstate->rel->rd_newRelfilenodeSubid == GetCurrentSubTransactionId())
+		{
+			hi_options |= HEAP_INSERT_COMMITTED;
+			if (cstate->freeze)
+				hi_options |= HEAP_INSERT_FROZEN;
+		}
 	}
 
+	if (cstate->freeze && (hi_options & HEAP_INSERT_FROZEN) == 0)
+		ereport(NOTICE,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("FREEZE option specified but pre-conditions not met")));
+
 	/*
 	 * We need a ResultRelInfo so we can use the regular executor's
 	 * index-entry-making machinery.  (There used to be a huge amount of code
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e4ff76e66e0..ad98b364f13 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -2383,6 +2383,10 @@ copy_opt_item:
 				{
 					$$ = makeDefElem("oids", (Node *)makeInteger(TRUE));
 				}
+			| FREEZE
+				{
+					$$ = makeDefElem("freeze", (Node *)makeInteger(TRUE));
+				}
 			| DELIMITER opt_as Sconst
 				{
 					$$ = makeDefElem("delimiter", (Node *)makeString($3));
diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index 5713bbe12ce..b981f975af5 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -1055,3 +1055,22 @@ pg_cursor(PG_FUNCTION_ARGS)
 
 	return (Datum) 0;
 }
+
+bool
+ThereAreNoReadyPortals(void)
+{
+	HASH_SEQ_STATUS status;
+	PortalHashEnt *hentry;
+
+	hash_seq_init(&status, PortalHashTable);
+
+	while ((hentry = (PortalHashEnt *) hash_seq_search(&status)) != NULL)
+	{
+		Portal		portal = hentry->portal;
+
+		if (portal->status == PORTAL_READY)
+			return false;
+	}
+
+	return true;
+}
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index fa514f6b48f..5705a2d75e9 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -1184,3 +1184,12 @@ DeleteAllExportedSnapshotFiles(void)
 
 	FreeDir(s_dir);
 }
+
+bool
+ThereAreNoPriorRegisteredSnapshots(void)
+{
+	if (RegisteredSnapshots <= 1)
+		return true;
+
+	return false;
+}
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 3be6b3a39f1..92627bfc25c 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -26,6 +26,8 @@
 /* "options" flag bits for heap_insert */
 #define HEAP_INSERT_SKIP_WAL	0x0001
 #define HEAP_INSERT_SKIP_FSM	0x0002
+#define HEAP_INSERT_COMMITTED	0x0004
+#define HEAP_INSERT_FROZEN		0x0008
 
 typedef struct BulkInsertStateData *BulkInsertState;
 
diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index daafd0e15e3..bfb03b88907 100644
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -220,5 +220,6 @@ extern void PortalDefineQuery(Portal portal,
 extern Node *PortalListGetPrimaryStmt(List *stmts);
 extern void PortalCreateHoldStore(Portal portal);
 extern void PortalHashTableDeleteAll(void);
+extern bool ThereAreNoReadyPortals(void);
 
 #endif   /* PORTAL_H */
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h
index 6b2ef80d067..da47e79eda3 100644
--- a/src/include/utils/snapmgr.h
+++ b/src/include/utils/snapmgr.h
@@ -48,5 +48,6 @@ extern Datum pg_export_snapshot(PG_FUNCTION_ARGS);
 extern void ImportSnapshot(const char *idstr);
 extern bool XactHasExportedSnapshots(void);
 extern void DeleteAllExportedSnapshotFiles(void);
+extern bool ThereAreNoPriorRegisteredSnapshots(void);
 
 #endif   /* SNAPMGR_H */
diff --git a/src/test/regress/expected/copy2.out b/src/test/regress/expected/copy2.out
index b1d07b3e1f0..d08f8cfdd47 100644
--- a/src/test/regress/expected/copy2.out
+++ b/src/test/regress/expected/copy2.out
@@ -254,6 +254,112 @@ SELECT * FROM testnull;
     | 
 (4 rows)
 
+CREATE TABLE vistest (LIKE testeoc);
+BEGIN;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV;
+SELECT * FROM vistest;
+ a 
+---
+ a
+ b
+(2 rows)
+
+SAVEPOINT s1;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV;
+SELECT * FROM vistest;
+ a 
+---
+ d
+ e
+(2 rows)
+
+COMMIT;
+BEGIN;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+SELECT * FROM vistest;
+ a 
+---
+ a
+ b
+(2 rows)
+
+SAVEPOINT s1;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+SELECT * FROM vistest;
+ a 
+---
+ d
+ e
+(2 rows)
+
+COMMIT;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+NOTICE:  FREEZE option specified but pre-conditions not met
+SELECT * FROM vistest;
+ a 
+---
+ a
+ b
+(2 rows)
+
+BEGIN;
+INSERT INTO vistest VALUES ('z');
+SAVEPOINT s1;
+TRUNCATE vistest;
+ROLLBACK TO SAVEPOINT s1;
+-- FREEZE should be silently ignored here
+COPY vistest FROM stdin CSV FREEZE;
+NOTICE:  FREEZE option specified but pre-conditions not met
+SELECT * FROM vistest;
+ a 
+---
+ a
+ b
+ z
+ d
+ e
+(5 rows)
+
+COMMIT;
+CREATE FUNCTION truncate_in_subxact() RETURNS VOID AS
+$$
+BEGIN
+  SELECT * FROM nonexistent;
+EXCEPTION
+  WHEN OTHERS THEN
+  	TRUNCATE vistest;
+END;
+$$ language plpgsql;
+BEGIN;
+INSERT INTO vistest VALUES ('z');
+SELECT truncate_in_subxact();
+ truncate_in_subxact 
+---------------------
+ 
+(1 row)
+
+COPY vistest FROM stdin CSV FREEZE;
+SELECT * FROM vistest;
+ a 
+---
+ d
+ e
+(2 rows)
+
+COMMIT;
+SELECT * FROM vistest;
+ a 
+---
+ d
+ e
+(2 rows)
+
+DROP TABLE vistest;
 DROP TABLE x, y;
 DROP FUNCTION fn_x_before();
 DROP FUNCTION fn_x_after();
diff --git a/src/test/regress/sql/copy2.sql b/src/test/regress/sql/copy2.sql
index 1961446fdb1..3b6da45439d 100644
--- a/src/test/regress/sql/copy2.sql
+++ b/src/test/regress/sql/copy2.sql
@@ -179,6 +179,84 @@ COPY testnull FROM stdin WITH NULL AS E'\\0';
 SELECT * FROM testnull;
 
 
+CREATE TABLE vistest (LIKE testeoc);
+BEGIN;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV;
+a
+b
+\.
+SELECT * FROM vistest;
+SAVEPOINT s1;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV;
+d
+e
+\.
+SELECT * FROM vistest;
+COMMIT;
+
+BEGIN;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+a
+b
+\.
+SELECT * FROM vistest;
+SAVEPOINT s1;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+d
+e
+\.
+SELECT * FROM vistest;
+COMMIT;
+BEGIN;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+x
+y
+\.
+SELECT * FROM vistest;
+COMMIT;
+TRUNCATE vistest;
+COPY vistest FROM stdin CSV FREEZE;
+p
+g
+\.
+BEGIN;
+INSERT INTO vistest VALUES ('z');
+SAVEPOINT s1;
+TRUNCATE vistest;
+ROLLBACK TO SAVEPOINT s1;
+-- FREEZE should be silently ignored here
+COPY vistest FROM stdin CSV FREEZE;
+d
+e
+\.
+SELECT * FROM vistest;
+COMMIT;
+CREATE FUNCTION truncate_in_subxact() RETURNS VOID AS
+$$
+BEGIN
+  SELECT * FROM nonexistent;
+EXCEPTION
+  WHEN OTHERS THEN
+  	TRUNCATE vistest;
+END;
+$$ language plpgsql;
+BEGIN;
+INSERT INTO vistest VALUES ('z');
+SELECT truncate_in_subxact();
+COPY vistest FROM stdin CSV FREEZE;
+d
+e
+\.
+SELECT * FROM vistest;
+COMMIT;
+SELECT * FROM vistest;
+DROP TABLE vistest;
+DROP FUNCTION truncate_in_subxact();
 DROP TABLE x, y;
 DROP FUNCTION fn_x_before();
 DROP FUNCTION fn_x_after();