revision-id: d1743600ff27f3db022f7d77a6f6bdc471c4e320 (mariadb-10.4.27-140-gd174360) parent(s): f33fc2fae5c3f3e80c4d24348609f3ce5246ca9c author: Igor Babaev committer: Igor Babaev timestamp: 2023-04-11 21:21:45 -0700 message: MDEV-20773 Error from UPDATE when estimating selectivity of a range This bug could affect multi-update statements as well as single-table update statements processed as multi-updates when the where condition contained a range condition over a non-indexed varchar column. The optimizer calculates selectivity of such range conditions using histograms. For each range the buckets containing endpoints of the the range are determined with a procedure that stores the values of the endpoints in the space of the record buffer where values of the columns are usually stored. For a range over a varchar column the value of a endpoint may exceed the size of the buffer and in such case the value is stored with truncation. This truncations cannot affect the result of the calculation of the range selectivity as the calculation employes only the beginning of the value string. However it can trigger generation of an unexpected error on this truncation if an update statement is processed. This patch prohibits truncation messages when selectivity of a range condition is calculated for a non-indexed column. Approved by Oleksandr Byelkin <sanja@mariadb.com> --- mysql-test/main/update.result | 29 +++++++++++++++++++++++++++++ mysql-test/main/update.test | 23 +++++++++++++++++++++++ sql/opt_range.cc | 3 +++ 3 files changed, 55 insertions(+) diff --git a/mysql-test/main/update.result b/mysql-test/main/update.result index f5edf1c..7b6426d 100644 --- a/mysql-test/main/update.result +++ b/mysql-test/main/update.result @@ -734,3 +734,32 @@ UPDATE t1,t2 SET t1.i1 = -39 WHERE t2.d1 <> t1.i1 AND t2.d1 = t1.d2; ERROR 22007: Incorrect datetime value: '19' for column `test`.`t1`.`i1` at row 1 DROP TABLE t1,t2; # End of MariaDB 10.2 tests +# +# MDEV-20773: UPDATE with LIKE predicate over non-indexed column +# of VARCHAR type +# +create table t1 (a1 varchar(30), a2 varchar(30) collate utf8_bin); +insert into t1 values +('aa','zzz'), ('b','xxaa'), ('ccc','yyy'), ('ddd','xxb'); +analyze table t1 persistent for all; +Table Op Msg_type Msg_text +test.t1 analyze status Engine-independent statistics collected +test.t1 analyze status OK +explain extended +update t1 set a1 = 'u' + where a2 like 'xx%' and exists(select 1 from t1 where t1.a1 < 'c'); +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY t1 ALL NULL NULL NULL NULL 4 49.22 Using where +2 SUBQUERY t1 ALL NULL NULL NULL NULL 4 50.00 Using where +Warnings: +Note 1003 /* select#1 */ update `test`.`t1` set `test`.`t1`.`a1` = 'u' where `test`.`t1`.`a2` like 'xx%' +update t1 set a1 = 'u' + where a2 like 'xx%' and exists(select 1 from t1 where t1.a1 < 'c'); +select * from t1; +a1 a2 +aa zzz +u xxaa +ccc yyy +u xxb +drop table t1; +# End of MariaDB 10.4 tests diff --git a/mysql-test/main/update.test b/mysql-test/main/update.test index 8a69494..147d69d 100644 --- a/mysql-test/main/update.test +++ b/mysql-test/main/update.test @@ -676,3 +676,26 @@ UPDATE t1,t2 SET t1.i1 = -39 WHERE t2.d1 <> t1.i1 AND t2.d1 = t1.d2; DROP TABLE t1,t2; --echo # End of MariaDB 10.2 tests + +--echo # +--echo # MDEV-20773: UPDATE with LIKE predicate over non-indexed column +--echo # of VARCHAR type +--echo # + +create table t1 (a1 varchar(30), a2 varchar(30) collate utf8_bin); +insert into t1 values + ('aa','zzz'), ('b','xxaa'), ('ccc','yyy'), ('ddd','xxb'); +analyze table t1 persistent for all; + +explain extended +update t1 set a1 = 'u' + where a2 like 'xx%' and exists(select 1 from t1 where t1.a1 < 'c'); + +update t1 set a1 = 'u' + where a2 like 'xx%' and exists(select 1 from t1 where t1.a1 < 'c'); + +select * from t1; + +drop table t1; + +--echo # End of MariaDB 10.4 tests diff --git a/sql/opt_range.cc b/sql/opt_range.cc index c344201..69a95f8 100644 --- a/sql/opt_range.cc +++ b/sql/opt_range.cc @@ -3518,7 +3518,10 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond) } else { + enum_check_fields save_count_cuted_fields= thd->count_cuted_fields; + thd->count_cuted_fields= CHECK_FIELD_IGNORE; rows= records_in_column_ranges(¶m, idx, key); + thd->count_cuted_fields= save_count_cuted_fields; if (rows != DBL_MAX) { key->field->cond_selectivity= rows/table_records;