MDEV-15562: Add dict_index_t::first_user_field()

dict_index_t::first_user_field(): Return the first data field in
a clustered index, that is, the field after the PRIMARY KEY and
the two system columns DB_TRX_ID, DB_ROLL_PTR.

dtuple_convert_big_rec(): Remove some local variables.

storage/innobase/data/data0data.cc

@@ -598,7 +598,6 @@ dtuple_convert_big_rec(
 	mem_heap_t*	heap;
 	big_rec_t*	vector;
 	dfield_t*	dfield;
-	dict_field_t*	ifield;
 	ulint		size;
 	ulint		n_fields;
 	ulint		local_len;
@@ -608,14 +607,7 @@ dtuple_convert_big_rec(
 		return(NULL);
 	}
 
-	if (!dict_table_has_atomic_blobs(index->table)) {
-		/* up to MySQL 5.1: store a 768-byte prefix locally */
-		local_len = BTR_EXTERN_FIELD_REF_SIZE
-			+ DICT_ANTELOPE_MAX_INDEX_COL_LEN;
-	} else {
-		/* new-format table: do not store any BLOB prefix locally */
-		local_len = BTR_EXTERN_FIELD_REF_SIZE;
-	}
+	ut_ad(index->n_uniq > 0);
 
 	ut_a(dtuple_check_typed_no_assert(entry));
 
@@ -638,24 +630,33 @@ dtuple_convert_big_rec(
 	stored externally */
 
 	n_fields = 0;
+	ulint longest_i;
+
+	if (!dict_table_has_atomic_blobs(index->table)) {
+		/* ROW_FORMAT=REDUNDANT or ROW_FORMAT=COMPACT:
+		store a 768-byte prefix locally */
+		local_len = BTR_EXTERN_FIELD_REF_SIZE
+			+ DICT_ANTELOPE_MAX_INDEX_COL_LEN;
+	} else {
+		/* ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED:
+		do not store any BLOB prefix locally */
+		local_len = BTR_EXTERN_FIELD_REF_SIZE;
+	}
 
 	while (page_zip_rec_needs_ext(rec_get_converted_size(index, entry,
 							     *n_ext),
 				      dict_table_is_comp(index->table),
 				      dict_index_get_n_fields(index),
 				      dict_table_page_size(index->table))) {
+		longest_i = 0;
 
-		ulint			i;
-		ulint			longest		= 0;
-		ulint			longest_i	= ULINT_MAX;
-		byte*			data;
-
-		for (i = dict_index_get_n_unique_in_tree(index);
-		     i < dtuple_get_n_fields(entry); i++) {
+		for (ulint i = index->first_user_field(), longest = 0;
+		     i < entry->n_fields; i++) {
 			ulint	savings;
-
 			dfield = dtuple_get_nth_field(entry, i);
-			ifield = dict_index_get_nth_field(index, i);
+
+			const dict_field_t* ifield = dict_index_get_nth_field(
+				index, i);
 
 			/* Skip fixed-length, NULL, externally stored,
 			or short columns */
@@ -697,7 +698,7 @@ dtuple_convert_big_rec(
 			continue;
 		}
 
-		if (!longest) {
+		if (!longest_i) {
 			/* Cannot shorten more */
 
 			mem_heap_free(heap);
@@ -712,7 +713,6 @@ dtuple_convert_big_rec(
 		from locally stored data. */
 
 		dfield = dtuple_get_nth_field(entry, longest_i);
-		ifield = dict_index_get_nth_field(index, longest_i);
 		local_prefix_len = local_len - BTR_EXTERN_FIELD_REF_SIZE;
 
 		vector->append(
@@ -723,7 +723,8 @@ dtuple_convert_big_rec(
 				+ local_prefix_len));
 
 		/* Allocate the locally stored part of the column. */
-		data = static_cast<byte*>(mem_heap_alloc(heap, local_len));
+		byte* data = static_cast<byte*>(
+			mem_heap_alloc(heap, local_len));
 
 		/* Copy the local prefix. */
 		memcpy(data, dfield_get_data(dfield), local_prefix_len);
@@ -737,7 +738,6 @@ dtuple_convert_big_rec(
 		UNIV_MEM_ALLOC(data + local_prefix_len,
 			       BTR_EXTERN_FIELD_REF_SIZE);
 #endif
-
 		dfield_set_data(dfield, data, local_len);
 		dfield_set_ext(dfield);
 

storage/innobase/include/dict0mem.h

@@ -1055,6 +1055,13 @@ struct dict_index_t{
 	/** @return whether the index includes virtual columns */
 	bool has_virtual() const { return type & DICT_VIRTUAL; }
 
+	/** @return the offset of the metadata BLOB field,
+	or the first user field after the PRIMARY KEY,DB_TRX_ID,DB_ROLL_PTR */
+	unsigned first_user_field() const {
+		ut_ad(is_primary());
+		return n_uniq + 2;
+	}
+
 	/** @return whether the index is corrupted */
 	inline bool is_corrupted() const;
 

storage/innobase/rem/rem0rec.cc

@@ -1906,6 +1906,7 @@ rec_copy_prefix_to_buf(
 		/* We would have !index->is_instant() when rolling back
 		an instant ADD COLUMN operation. */
 		ut_ad(index->is_instant() || page_rec_is_metadata(rec));
+		ut_ad(n_fields <= index->first_user_field());
 		nulls++;
 		const ulint n_rec = ulint(index->n_core_fields) + 1
 			+ rec_get_n_add_field(nulls);

storage/innobase/row/row0log.cc

@@ -684,9 +684,9 @@ row_log_table_delete(
 		fields of the record. */
 		heap = mem_heap_create(
 			DATA_TRX_ID_LEN
-			+ DTUPLE_EST_ALLOC(unsigned(new_index->n_uniq) + 2));
-		old_pk = tuple = dtuple_create(
-			heap, unsigned(new_index->n_uniq) + 2);
+			+ DTUPLE_EST_ALLOC(new_index->first_user_field()));
+		old_pk = tuple = dtuple_create(heap,
+					       new_index->first_user_field());
 		dict_index_copy_types(tuple, new_index, tuple->n_fields);
 		dtuple_set_n_fields_cmp(tuple, new_index->n_uniq);
 
@@ -1919,8 +1919,7 @@ row_log_table_apply_delete(
 	btr_pcur_t	pcur;
 	ulint*		offsets;
 
-	ut_ad(rec_offs_n_fields(moffsets)
-	      == dict_index_get_n_unique(index) + 2);
+	ut_ad(rec_offs_n_fields(moffsets) == index->first_user_field());
 	ut_ad(!rec_offs_any_extern(moffsets));
 
 	/* Convert the row to a search tuple. */
@@ -2483,8 +2482,7 @@ row_log_table_apply_op(
 		/* The ROW_T_DELETE record was converted by
 		rec_convert_dtuple_to_temp() using new_index. */
 		ut_ad(!new_index->is_instant());
-		rec_offs_set_n_fields(offsets,
-				      unsigned(new_index->n_uniq) + 2);
+		rec_offs_set_n_fields(offsets, new_index->first_user_field());
 		rec_init_offsets_temp(mrec, new_index, offsets);
 		next_mrec = mrec + rec_offs_data_size(offsets);
 		if (next_mrec > mrec_end) {
@@ -2576,7 +2574,7 @@ row_log_table_apply_op(
 			rec_convert_dtuple_to_temp() using new_index. */
 			ut_ad(!new_index->is_instant());
 			rec_offs_set_n_fields(offsets,
-					      unsigned(new_index->n_uniq) + 2);
+					      new_index->first_user_field());
 			rec_init_offsets_temp(mrec, new_index, offsets);
 
 			next_mrec = mrec + rec_offs_data_size(offsets);
@@ -2586,13 +2584,12 @@ row_log_table_apply_op(
 
 			/* Copy the PRIMARY KEY fields and
 			DB_TRX_ID, DB_ROLL_PTR from mrec to old_pk. */
-			old_pk = dtuple_create(
-				heap, unsigned(new_index->n_uniq) + 2);
+			old_pk = dtuple_create(heap,
+					       new_index->first_user_field());
 			dict_index_copy_types(old_pk, new_index,
 					      old_pk->n_fields);
 
-			for (ulint i = 0;
-			     i < dict_index_get_n_unique(new_index) + 2;
+			for (ulint i = 0; i < new_index->first_user_field();
 			     i++) {
 				const void*	field;
 				ulint		len;
@@ -2743,8 +2740,8 @@ row_log_table_apply_ops(
 	dict_index_t*	new_index	= dict_table_get_first_index(
 		new_table);
 	const ulint	i		= 1 + REC_OFFS_HEADER_SIZE
-		+ ut_max(dict_index_get_n_fields(index),
-			 dict_index_get_n_unique(new_index) + 2);
+		+ std::max<ulint>(index->n_fields,
+				  new_index->first_user_field());
 	const ulint	new_trx_id_col	= dict_col_get_clust_pos(
 		dict_table_get_sys_col(new_table, DATA_TRX_ID), new_index);
 	trx_t*		trx		= thr_get_trx(thr);