Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com

doc/src/sgml/storage.sgml

@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to

src/backend/access/common/Makefile

@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/access/common/detoast.c

@@ -0,0 +1,869 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Retrieve compressed or external variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+											   int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 residx, nextidx,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 residx, numchunks,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+										 chunksize,
+										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 residx,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 residx,
+									 0, numchunks - 1,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 nextidx,
+								 toast_pointer.va_valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32		rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+							  VARDATA(result),
+							  slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}

src/backend/access/common/heaptuple.c

@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 

src/backend/access/common/indextuple.c

@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines

src/backend/access/common/reloptions.c

@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"

src/backend/access/common/toast_internals.c

@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}

src/backend/access/heap/Makefile

@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/access/heap/heapam.c

@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"

src/backend/access/heap/heapam_handler.c

@@ -23,11 +23,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"

src/backend/access/heap/heaptoast.c

@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}

src/backend/access/heap/rewriteheap.c

@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 

src/backend/access/transam/xlog.c

@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"

src/backend/commands/analyze.c

@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"

src/backend/commands/cluster.c

@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"

src/backend/executor/execExprInterp.c

@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"

src/backend/executor/execTuples.c

@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"

src/backend/executor/tstoreReceiver.c

@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 

src/backend/replication/logical/reorderbuffer.c

@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"

src/backend/statistics/extended_stats.c

@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"

src/backend/storage/large_object/inv_api.c

@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"

src/backend/utils/adt/array_typanalyze.c

@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"

src/backend/utils/adt/datum.c

@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"

src/backend/utils/adt/expandedrecord.c

@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"

src/backend/utils/adt/rowtypes.c

@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"

src/backend/utils/adt/tsgistidx.c

@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"

src/backend/utils/adt/varchar.c

@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"

src/backend/utils/adt/varlena.c

@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"

src/backend/utils/cache/catcache.c

@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"

src/backend/utils/fmgr/fmgr.c

@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"

src/bin/pg_resetwal/pg_resetwal.c

@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"

src/include/access/detoast.h

@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */

src/include/access/heaptoast.h

@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
+ * heaptoast.h
- *	  POSTGRES definitions for external and compressed storage
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
+#ifndef HEAPTOAST_H
-#define TUPTOASTER_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-													 int32 sliceoffset,
-													 int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
-/* ----------
+#endif							/* HEAPTOAST_H */
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */

src/include/access/toast_internals.h

@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+							  struct varlena *oldexternal, int options);
+
+extern int	toast_open_indexes(Relation toastrel,
+							   LOCKMODE lock,
+							   Relation **toastidxs,
+							   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+								LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */

src/pl/plpgsql/src/pl_exec.c

@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"

src/test/regress/regress.c

@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"