branches/zip: Speed up rec_offs_any_extern() and rec_offs_n_extern()

by adding the REC_OFFS_EXTERNAL flag to rec_offs_base(offsets)[0].

This reduces the processor usage of page_zip_write_rec() by about 40%
in one test case.  The code could be sped up further by testing
rec_offs_any_extern() outside of loops that check rec_offs_nth_extern().
The vast majority of records does not contain any externally stored columns.

include/rem0rec.h

@@ -420,6 +420,15 @@ rec_offs_comp(
 				/* out: nonzero if compact format */
 	const ulint*	offsets);/* in: array returned by rec_get_offsets() */
 /**********************************************************
+Determine if the offsets are for a record containing
+externally stored columns. */
+UNIV_INLINE
+ulint
+rec_offs_any_extern(
+/*================*/
+				/* out: nonzero if externally stored */
+	const ulint*	offsets);/* in: array returned by rec_get_offsets() */
+/**********************************************************
 Returns nonzero if the extern bit is set in nth field of rec. */
 UNIV_INLINE
 ulint
@@ -448,15 +457,6 @@ rec_offs_nth_size(
 	ulint		n);	/* in: nth field */
 
 /**********************************************************
-Returns TRUE if the extern bit is set in any of the fields
-of a record. */
-UNIV_INLINE
-ibool
-rec_offs_any_extern(
-/*================*/
-				/* out: TRUE if a field is stored externally */
-	const ulint*	offsets);/* in: array returned by rec_get_offsets() */
-/**********************************************************
 Returns the number of extern bits set in a record. */
 UNIV_INLINE
 ulint

include/rem0rec.ic

@@ -1045,6 +1045,20 @@ rec_offs_comp(
 	return(*rec_offs_base(offsets) & REC_OFFS_COMPACT);
 }
 
+/**********************************************************
+Determine if the offsets are for a record containing
+externally stored columns. */
+UNIV_INLINE
+ulint
+rec_offs_any_extern(
+/*================*/
+				/* out: nonzero if externally stored */
+	const ulint*	offsets)/* in: array returned by rec_get_offsets() */
+{
+	ut_ad(rec_offs_validate(NULL, NULL, offsets));
+	return(UNIV_UNLIKELY(*rec_offs_base(offsets) & REC_OFFS_EXTERNAL));
+}
+
 /**********************************************************
 Returns nonzero if the extern bit is set in nth field of rec. */
 UNIV_INLINE
@@ -1093,25 +1107,6 @@ rec_offs_nth_size(
 	       & REC_OFFS_MASK);
 }
 
-/**********************************************************
-Returns TRUE if the extern bit is set in any of the fields
-of a record. */
-UNIV_INLINE
-ibool
-rec_offs_any_extern(
-/*================*/
-				/* out: TRUE if a field is stored externally */
-	const ulint*	offsets)/* in: array returned by rec_get_offsets() */
-{
-	ulint	i;
-	for (i = rec_offs_n_fields(offsets); i--; ) {
-		if (rec_offs_nth_extern(offsets, i)) {
-			return(TRUE);
-		}
-	}
-	return(FALSE);
-}
-
 /**********************************************************
 Returns the number of extern bits set in a record. */
 UNIV_INLINE
@@ -1121,13 +1116,18 @@ rec_offs_n_extern(
 				/* out: number of externally stored fields */
 	const ulint*	offsets)/* in: array returned by rec_get_offsets() */
 {
-	ulint	i;
 	ulint	n = 0;
-	for (i = rec_offs_n_fields(offsets); i--; ) {
-		if (rec_offs_nth_extern(offsets, i)) {
-			n++;
+
+	if (rec_offs_any_extern(offsets)) {
+		ulint	i;
+
+		for (i = rec_offs_n_fields(offsets); i--; ) {
+			if (rec_offs_nth_extern(offsets, i)) {
+				n++;
+			}
 		}
 	}
+
 	return(n);
 }
 
@@ -1416,7 +1416,7 @@ rec_offs_extra_size(
 {
 	ulint	size;
 	ut_ad(rec_offs_validate(NULL, NULL, offsets));
-	size = *rec_offs_base(offsets) & ~REC_OFFS_COMPACT;
+	size = *rec_offs_base(offsets) & ~(REC_OFFS_COMPACT | REC_OFFS_EXTERNAL);
 	ut_ad(size < UNIV_PAGE_SIZE);
 	return(size);
 }

page/page0zip.c

@@ -2200,6 +2200,9 @@ page_zip_decompress_clust(
 		columns in this record.  For each externally
 		stored column, restore or clear the
 		BTR_EXTERN_FIELD_REF. */
+		if (!rec_offs_any_extern(offsets)) {
+			continue;
+		}
 
 		for (i = 0; i < rec_offs_n_fields(offsets); i++) {
 			if (!rec_offs_nth_extern(offsets, i)) {
@@ -3159,16 +3162,20 @@ page_zip_clear_rec(
 		/* Do not clear the record, because there is not enough space
 		to log the operation. */
 
-		ulint	i;
-		for (i = rec_offs_n_fields(offsets); i--; ) {
-			/* Clear all BLOB pointers in order to make
-			page_zip_validate() pass. */
-			if (rec_offs_nth_extern(offsets, i)) {
-				ulint	len;
-				byte*	field = rec_get_nth_field(rec, offsets,
-								  i, &len);
-				memset(field + len - BTR_EXTERN_FIELD_REF_SIZE,
-				       0, BTR_EXTERN_FIELD_REF_SIZE);
+		if (rec_offs_any_extern(offsets)) {
+			ulint	i;
+
+			for (i = rec_offs_n_fields(offsets); i--; ) {
+				/* Clear all BLOB pointers in order to make
+				page_zip_validate() pass. */
+				if (rec_offs_nth_extern(offsets, i)) {
+					ulint	len;
+					byte*	field = rec_get_nth_field(
+						rec, offsets, i, &len);
+					memset(field + len
+					       - BTR_EXTERN_FIELD_REF_SIZE,
+					       0, BTR_EXTERN_FIELD_REF_SIZE);
+				}
 			}
 		}
 	}

rem/rem0rec.c

@@ -218,7 +218,8 @@ ulint, where rec_offs_n_fields(offsets) has been initialized to the
 number of fields in the record.	 The rest of the array will be
 initialized by this function.  rec_offs_base(offsets)[0] will be set
 to the extra size (if REC_OFFS_COMPACT is set, the record is in the
-new format), and rec_offs_base(offsets)[1..n_fields] will be set to
+new format; if REC_OFFS_EXTERNAL is set, the record contains externally
+stored columns), and rec_offs_base(offsets)[1..n_fields] will be set to
 offsets past the end of fields 0..n_fields, or to the beginning of
 fields 1..n_fields+1.  When the high-order bit of the offset at [i+1]
 is set (REC_OFFS_SQL_NULL), the field i is NULL.  When the second
@@ -240,6 +241,7 @@ rec_init_offsets(
 	rec_offs_make_valid(rec, index, offsets);
 
 	if (dict_table_is_comp(index->table)) {
+		ulint		any_ext;
 		const byte*	nulls;
 		const byte*	lens;
 		dict_field_t*	field;
@@ -266,6 +268,7 @@ rec_init_offsets(
 		nulls = rec - (REC_N_NEW_EXTRA_BYTES + 1);
 		lens = nulls - (index->n_nullable + 7) / 8;
 		offs = 0;
+		any_ext = 0;
 		null_mask = 1;
 
 		/* read the lengths of fields 0..n */
@@ -316,6 +319,7 @@ rec_init_offsets(
 								  & 0x4000)) {
 							ut_ad(dict_index_is_clust
 							      (index));
+							any_ext = REC_OFFS_EXTERNAL;
 							len = offs
 								| REC_OFFS_EXTERNAL;
 						} else {
@@ -335,7 +339,7 @@ rec_init_offsets(
 		} while (++i < rec_offs_n_fields(offsets));
 
 		*rec_offs_base(offsets)
-			= (rec - (lens + 1)) | REC_OFFS_COMPACT;
+			= (rec - (lens + 1)) | REC_OFFS_COMPACT | any_ext;
 	} else {
 		/* Old-style record: determine extra size and end offsets */
 		offs = REC_N_OLD_EXTRA_BYTES;
@@ -364,6 +368,7 @@ rec_init_offsets(
 				if (offs & REC_2BYTE_EXTERN_MASK) {
 					offs &= ~REC_2BYTE_EXTERN_MASK;
 					offs |= REC_OFFS_EXTERNAL;
+					*rec_offs_base(offsets) |= REC_OFFS_EXTERNAL;
 				}
 				rec_offs_base(offsets)[1 + i] = offs;
 			} while (++i < rec_offs_n_fields(offsets));
@@ -459,6 +464,7 @@ rec_get_offsets_reverse(
 	ulint		n;
 	ulint		i;
 	ulint		offs;
+	ulint		any_ext;
 	const byte*	nulls;
 	const byte*	lens;
 	dict_field_t*	field;
@@ -485,6 +491,7 @@ rec_get_offsets_reverse(
 	lens = nulls + (index->n_nullable + 7) / 8;
 	i = offs = 0;
 	null_mask = 1;
+	any_ext = 0;
 
 	/* read the lengths of fields 0..n */
 	do {
@@ -529,6 +536,7 @@ rec_get_offsets_reverse(
 
 					offs += len & 0x3fff;
 					if (UNIV_UNLIKELY(len & 0x4000)) {
+						any_ext = REC_OFFS_EXTERNAL;
 						len = offs | REC_OFFS_EXTERNAL;
 					} else {
 						len = offs;
@@ -548,7 +556,7 @@ rec_get_offsets_reverse(
 
 	ut_ad(lens >= extra);
 	*rec_offs_base(offsets) = (lens - extra + REC_N_NEW_EXTRA_BYTES)
-		| REC_OFFS_COMPACT;
+		| REC_OFFS_COMPACT | any_ext;
 }
 
 /****************************************************************