Mostly-cosmetic adjustments of TOAST-related macros.

The authors of bbe0a81db hadn't quite got the idea that macros named
like SOMETHING_4B_C were only meant for internal endianness-related
details in postgres.h.  Choose more legible names for macros that are
intended to be used elsewhere.  Rearrange postgres.h a bit to clarify
the separation between those internal macros and ones intended for
wider use.

Also, avoid using the term "rawsize" for true decompressed size;
we've used "extsize" for that, because "rawsize" generally denotes
total Datum size including header.  This choice seemed particularly
unfortunate in tests that were comparing one of these meanings to
the other.

This patch includes a couple of not-purely-cosmetic changes: be
sure that the shifts aligning compression methods are unsigned
(not critical today, but will be when compression method 2 exists),
and fix broken definition of VARATT_EXTERNAL_GET_COMPRESSION (now
VARATT_EXTERNAL_GET_COMPRESS_METHOD), whose callers worked only
accidentally.

Discussion: https://postgr.es/m/574197.1616428079@sss.pgh.pa.us

3 files changed, 26 insertions, 26 deletions

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index bed50e86034..a7f7a474782 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -251,7 +251,7 @@ detoast_attr_slice(struct varlena *attr,
 			 * determine how much compressed data we need to be sure of being
 			 * able to decompress the required slice.
 			 */
-			if (VARATT_EXTERNAL_GET_COMPRESSION(toast_pointer) ==
+			if (VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer) ==
 				TOAST_PGLZ_COMPRESSION_ID)
 				max_size = pglz_maximum_compressed_size(slicelimit, max_size);
 
@@ -562,7 +562,7 @@ toast_raw_datum_size(Datum value)
 	else if (VARATT_IS_COMPRESSED(attr))
 	{
 		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+		result = VARDATA_COMPRESSED_GET_EXTSIZE(attr) + VARHDRSZ;
 	}
 	else if (VARATT_IS_SHORT(attr))
 	{
diff --git a/src/backend/access/common/toast_compression.c b/src/backend/access/common/toast_compression.c
index 00af1740cfa..645eb03bf07 100644
--- a/src/backend/access/common/toast_compression.c
+++ b/src/backend/access/common/toast_compression.c
@@ -53,11 +53,11 @@ pglz_compress_datum(const struct varlena *value)
 	 * that will be needed for varlena overhead, and allocate that amount.
 	 */
 	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									VARHDRSZ_COMPRESS);
+									VARHDRSZ_COMPRESSED);
 
 	len = pglz_compress(VARDATA_ANY(value),
 						valsize,
-						(char *) tmp + VARHDRSZ_COMPRESS,
+						(char *) tmp + VARHDRSZ_COMPRESSED,
 						NULL);
 	if (len < 0)
 	{
@@ -65,7 +65,7 @@ pglz_compress_datum(const struct varlena *value)
 		return NULL;
 	}
 
-	SET_VARSIZE_COMPRESSED(tmp, len + VARHDRSZ_COMPRESS);
+	SET_VARSIZE_COMPRESSED(tmp, len + VARHDRSZ_COMPRESSED);
 
 	return tmp;
 }
@@ -80,13 +80,13 @@ pglz_decompress_datum(const struct varlena *value)
 	int32		rawsize;
 
 	/* allocate memory for the uncompressed data */
-	result = (struct varlena *) palloc(VARRAWSIZE_4B_C(value) + VARHDRSZ);
+	result = (struct varlena *) palloc(VARDATA_COMPRESSED_GET_EXTSIZE(value) + VARHDRSZ);
 
 	/* decompress the data */
-	rawsize = pglz_decompress((char *) value + VARHDRSZ_COMPRESS,
-							  VARSIZE(value) - VARHDRSZ_COMPRESS,
+	rawsize = pglz_decompress((char *) value + VARHDRSZ_COMPRESSED,
+							  VARSIZE(value) - VARHDRSZ_COMPRESSED,
 							  VARDATA(result),
-							  VARRAWSIZE_4B_C(value), true);
+							  VARDATA_COMPRESSED_GET_EXTSIZE(value), true);
 	if (rawsize < 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
@@ -111,8 +111,8 @@ pglz_decompress_datum_slice(const struct varlena *value,
 	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
 
 	/* decompress the data */
-	rawsize = pglz_decompress((char *) value + VARHDRSZ_COMPRESS,
-							  VARSIZE(value) - VARHDRSZ_COMPRESS,
+	rawsize = pglz_decompress((char *) value + VARHDRSZ_COMPRESSED,
+							  VARSIZE(value) - VARHDRSZ_COMPRESSED,
 							  VARDATA(result),
 							  slicelength, false);
 	if (rawsize < 0)
@@ -149,10 +149,10 @@ lz4_compress_datum(const struct varlena *value)
 	 * that will be needed for varlena overhead, and allocate that amount.
 	 */
 	max_size = LZ4_compressBound(valsize);
-	tmp = (struct varlena *) palloc(max_size + VARHDRSZ_COMPRESS);
+	tmp = (struct varlena *) palloc(max_size + VARHDRSZ_COMPRESSED);
 
 	len = LZ4_compress_default(VARDATA_ANY(value),
-							   (char *) tmp + VARHDRSZ_COMPRESS,
+							   (char *) tmp + VARHDRSZ_COMPRESSED,
 							   valsize, max_size);
 	if (len <= 0)
 		elog(ERROR, "lz4 compression failed");
@@ -164,7 +164,7 @@ lz4_compress_datum(const struct varlena *value)
 		return NULL;
 	}
 
-	SET_VARSIZE_COMPRESSED(tmp, len + VARHDRSZ_COMPRESS);
+	SET_VARSIZE_COMPRESSED(tmp, len + VARHDRSZ_COMPRESSED);
 
 	return tmp;
 #endif
@@ -184,13 +184,13 @@ lz4_decompress_datum(const struct varlena *value)
 	struct varlena *result;
 
 	/* allocate memory for the uncompressed data */
-	result = (struct varlena *) palloc(VARRAWSIZE_4B_C(value) + VARHDRSZ);
+	result = (struct varlena *) palloc(VARDATA_COMPRESSED_GET_EXTSIZE(value) + VARHDRSZ);
 
 	/* decompress the data */
-	rawsize = LZ4_decompress_safe((char *) value + VARHDRSZ_COMPRESS,
+	rawsize = LZ4_decompress_safe((char *) value + VARHDRSZ_COMPRESSED,
 								  VARDATA(result),
-								  VARSIZE(value) - VARHDRSZ_COMPRESS,
-								  VARRAWSIZE_4B_C(value));
+								  VARSIZE(value) - VARHDRSZ_COMPRESSED,
+								  VARDATA_COMPRESSED_GET_EXTSIZE(value));
 	if (rawsize < 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
@@ -224,9 +224,9 @@ lz4_decompress_datum_slice(const struct varlena *value, int32 slicelength)
 	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
 
 	/* decompress the data */
-	rawsize = LZ4_decompress_safe_partial((char *) value + VARHDRSZ_COMPRESS,
+	rawsize = LZ4_decompress_safe_partial((char *) value + VARHDRSZ_COMPRESSED,
 										  VARDATA(result),
-										  VARSIZE(value) - VARHDRSZ_COMPRESS,
+										  VARSIZE(value) - VARHDRSZ_COMPRESSED,
 										  slicelength,
 										  slicelength);
 	if (rawsize < 0)
@@ -262,10 +262,10 @@ toast_get_compression_id(struct varlena *attr)
 		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 		if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			cmid = VARATT_EXTERNAL_GET_COMPRESSION(toast_pointer);
+			cmid = VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer);
 	}
 	else if (VARATT_IS_COMPRESSED(attr))
-		cmid = VARCOMPRESS_4B_C(attr);
+		cmid = VARDATA_COMPRESSED_GET_COMPRESS_METHOD(attr);
 
 	return cmid;
 }
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index c81ce178221..730cd04a2d7 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -91,7 +91,7 @@ toast_compress_datum(Datum value, char cmethod)
 	{
 		/* successful compression */
 		Assert(cmid != TOAST_INVALID_COMPRESSION_ID);
-		TOAST_COMPRESS_SET_SIZE_AND_METHOD(tmp, valsize, cmid);
+		TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(tmp, valsize, cmid);
 		return PointerGetDatum(tmp);
 	}
 	else
@@ -181,11 +181,11 @@ toast_save_datum(Relation rel, Datum value,
 		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_rawsize = VARDATA_COMPRESSED_GET_EXTSIZE(dval) + VARHDRSZ;
 
 		/* set external size and compression method */
-		VARATT_EXTERNAL_SET_SIZE_AND_COMPRESSION(toast_pointer, data_todo,
-												 VARCOMPRESS_4B_C(dval));
+		VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer, data_todo,
+													 VARDATA_COMPRESSED_GET_COMPRESS_METHOD(dval));
 		/* Assert that the numbers look like it's compressed */
 		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 	}