diff options
Diffstat (limited to 'sql/sql_update.cc')
| -rw-r--r-- | sql/sql_update.cc | 46 |
1 files changed, 28 insertions, 18 deletions
diff --git a/sql/sql_update.cc b/sql/sql_update.cc index ec91f2c64fc..6a4027318d5 100644 --- a/sql/sql_update.cc +++ b/sql/sql_update.cc @@ -25,9 +25,26 @@ #include "sql_trigger.h" #include "debug_sync.h" -/* Return 0 if row hasn't changed */ -bool compare_record(TABLE *table) +/** + True if the table's input and output record buffers are comparable using + compare_record(TABLE*). + */ +bool records_are_comparable(const TABLE *table) { + return ((table->file->ha_table_flags() & HA_PARTIAL_COLUMN_READ) == 0) || + bitmap_is_subset(table->write_set, table->read_set); +} + + +/** + Compares the input and outbut record buffers of the table to see if a row + has changed. + + @return true if row has changed. + @return false otherwise. +*/ + +bool compare_record(const TABLE *table) { if (table->s->can_cmp_whole_record) return cmp_record(table,record[1]); @@ -583,9 +600,7 @@ int mysql_update(THD *thd, the table handler is returning all columns OR if if all updated columns are read */ - can_compare_record= (!(table->file->ha_table_flags() & - HA_PARTIAL_COLUMN_READ) || - bitmap_is_subset(table->write_set, table->read_set)); + can_compare_record= records_are_comparable(table); while (!(error=info.read_record(&info)) && !thd->killed) { @@ -1698,18 +1713,16 @@ bool multi_update::send_data(List<Item> ¬_used_values) if (table->status & (STATUS_NULL_ROW | STATUS_UPDATED)) continue; - /* - We can use compare_record() to optimize away updates if - the table handler is returning all columns OR if - if all updated columns are read - */ if (table == table_to_update) { + /* + We can use compare_record() to optimize away updates if + the table handler is returning all columns OR if + if all updated columns are read + */ bool can_compare_record; - can_compare_record= (!(table->file->ha_table_flags() & - HA_PARTIAL_COLUMN_READ) || - bitmap_is_subset(table->write_set, - table->read_set)); + can_compare_record= records_are_comparable(table); + table->status|= STATUS_UPDATED; store_record(table,record[1]); if (fill_record_n_invoke_before_triggers(thd, *fields_for_table[offset], @@ -1962,10 +1975,7 @@ int multi_update::do_updates() goto err; } - can_compare_record= (!(table->file->ha_table_flags() & - HA_PARTIAL_COLUMN_READ) || - bitmap_is_subset(table->write_set, - table->read_set)); + can_compare_record= records_are_comparable(table); for (;;) { |