Add max_row_size to dict_table_t.

data/data0type.c

@@ -293,3 +293,36 @@ dtype_print(
 
 	fprintf(stderr, " len %lu prec %lu", (ulong) len, (ulong) type->prec);
 }
+
+/***************************************************************************
+Returns the maximum size of a data type. Note: types in system tables may be
+incomplete and return incorrect information. */
+UNIV_INLINE
+ulint
+dtype_get_max_size(
+/*===============*/
+				/* out: maximum size (ULINT_MAX for
+				unbounded types) */
+	const dtype_t*	type)	/* in: type */
+{
+	switch (type->mtype) {
+	case DATA_SYS:
+	case DATA_CHAR:
+	case DATA_FIXBINARY:
+	case DATA_INT:
+	case DATA_FLOAT:
+	case DATA_DOUBLE:
+	case DATA_MYSQL:
+	case DATA_VARCHAR:
+	case DATA_BINARY:
+	case DATA_DECIMAL:
+	case DATA_VARMYSQL:
+			return(type->len);
+	case DATA_BLOB:
+			return(ULINT_MAX);
+	default:
+		ut_error;
+	}
+
+	return(ULINT_MAX);
+}

dict/dict0dict.c

@@ -861,6 +861,7 @@ dict_table_add_to_cache(
 	ulint	fold;
 	ulint	id_fold;
 	ulint	i;
+	ulint	row_len;
 
 	ut_ad(table);
 #ifdef UNIV_SYNC_DEBUG
@@ -908,6 +909,24 @@ dict_table_add_to_cache(
 #error "DATA_N_SYS_COLS != 4"
 #endif
 
+	row_len = 0;
+	for (i = 0; i < table->n_def; i++) {
+		ulint	col_len = dtype_get_max_size(
+			dict_col_get_type(dict_table_get_nth_col(table, i)));
+
+		/* If we have a single unbounded field, or several gigantic
+		fields, mark the maximum row size as ULINT_MAX. */
+		if (ut_max(col_len, row_len) >= (ULINT_MAX / 2)) {
+			row_len = ULINT_MAX;
+
+			break;
+		}
+
+		row_len += col_len;
+	}
+
+	table->max_row_size = row_len;
+
 	/* Look for a table with the same name: error if such exists */
 	{
 		dict_table_t*	table2;

dict/dict0mem.c

@@ -82,6 +82,8 @@ dict_mem_table_create(
 
 	table->stat_modified_counter = 0;
 
+	table->max_row_size = 0;
+
 	mutex_create(&table->autoinc_mutex, SYNC_DICT_AUTOINC_MUTEX);
 
 	table->autoinc_inited = FALSE;

include/data0type.h

@@ -330,6 +330,16 @@ dtype_get_min_size(
 				/* out: minimum size */
 	const dtype_t*	type);	/* in: type */
 /***************************************************************************
+Returns the maximum size of a data type. Note: types in system tables may be
+incomplete and return incorrect information. */
+UNIV_INLINE
+ulint
+dtype_get_max_size(
+/*===============*/
+				/* out: maximum size (ULINT_MAX for
+				unbounded types) */
+	const dtype_t*	type);	/* in: type */
+/***************************************************************************
 Returns a stored SQL NULL size for a type. For fixed length types it is
 the fixed length of the type, otherwise 0. */
 UNIV_INLINE

include/dict0mem.h

@@ -341,6 +341,12 @@ struct dict_table_struct{
 				had an IX lock on */
 	UT_LIST_BASE_NODE_T(lock_t)
 			locks; /* list of locks on the table */
+	ulint		max_row_size;
+				/* maximum size of a single row in the
+				table, not guaranteed to be especially
+				accurate. it's ULINT_MAX if there are
+				unbounded variable-width fields. initialized
+				in dict_table_add_to_cache. */
 	/*----------------------*/
 	ibool		does_not_fit_in_memory;
 				/* this field is used to specify in simulations