Hi Varun,
First, Some input on the test:
On Wed, Mar 27, 2019 at 01:55:16PM +0530, Varun wrote:
> revision-id: e0fa1993692a3552feddae56cbee3078d4da2121
> (mariadb-10.2.22-91-ge0fa1993692)
> parent(s): 50a8fc52988d13a5164a1a542b9d7a85e3ecc1c1
> author: Varun Gupta
> committer: Varun Gupta
> timestamp: 2019-03-27 13:48:44 +0530
> message:
>
> MDEV-18899: Server crashes in Field::set_warning_truncated_wrong_value
>
> To fix the crash there we need to make sure that the
> server while storing the statistical values in statistical tables should do it
> in a multi-byte safe way.
> Also there is no need to throw warnings if there is truncation while storing
> values from statistical fields.
>
...
> --- a/mysql-test/r/stat_tables_innodb.result
> +++ b/mysql-test/r/stat_tables_innodb.result
> @@ -651,6 +651,63 @@ SELECT MAX(pk) FROM t1;
> MAX(pk)
> NULL
> DROP TABLE t1;
> +#
> +# MDEV-18899: Server crashes in Field::set_warning_truncated_wrong_value
> +#
> +set names utf8;
> +set
> @save_optimizer_use_condition_selectivity=@@optimizer_use_condition_selectivity;
> +set optimizer_use_condition_selectivity=4;
> +set use_stat_tables=preferably;
> +set @save_histogram_size= @@histogram_size;
> +set histogram_size=255;
> +create table t1 ( a varchar(255) character set utf8);
> +insert into t1 values (REPEAT('ӥ',255)), (REPEAT('ç',255));
> +analyze table t1;
> +Table Op Msg_type Msg_text
> +test.t1 analyze status Engine-independent statistics collected
> +test.t1 analyze status OK
> +select HEX(RIGHT(min_value, 1)), length(min_value) from mysql.column_stats;
> +HEX(RIGHT(min_value, 1)) length(min_value)
> +A7 254
> +select HEX(RIGHT(max_value, 1)), length(max_value) from mysql.column_stats;
> +HEX(RIGHT(max_value, 1)) length(max_value)
> +A5 254
> +analyze select * from t1 where a >= 'ӥ';
> +id select_type table type possible_keys key key_len ref
> rows r_rows filtered r_filtered Extra
> +1 SIMPLE t1 ALL NULL NULL NULL NULL 2 2.00
> 50.00 50.00 Using where
> +set @save_sql_mode= @@sql_mode;
> +set
> sql_mode='ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
> +update mysql.column_stats set min_value= REPEAT('ӥ',255);
This looks scary, what if there were some other data in these tables?
Can you change add a WHERE db_name=database() and table_name='t1' ?
> +Warnings:
> +Warning 1265 Data truncated for column 'min_value' at row 1
> +select HEX(RIGHT(min_value, 1)), length(min_value) from mysql.column_stats;
> +HEX(RIGHT(min_value, 1)) length(min_value)
> +D3 255
> +analyze select * from t1 where a >= 'ӥ';
> +id select_type table type possible_keys key key_len ref
> rows r_rows filtered r_filtered Extra
> +1 SIMPLE t1 ALL NULL NULL NULL NULL 2 2.00
> 50.00 50.00 Using where
> +set names latin1;
> +drop table t1;
> +CREATE TABLE t1 (col1 date);
> +INSERT INTO t1 VALUES('2004-01-01'),('2004-02-29');
> +INSERT INTO t1 VALUES('0000-10-31');
> +analyze table t1;
> +Table Op Msg_type Msg_text
> +test.t1 analyze status Engine-independent statistics collected
> +test.t1 analyze status OK
> +update mysql.column_stats set min_value='2004-0-31123';
The same as above.
> +select min_value from mysql.column_stats;
> +min_value
> +2004-0-31123
This case also makes one wonder whether not producing a warning was a good idea
after all.
A varchar string that is 255-byte long, and after 255 bytes it gets truncated
in the middle of a character is a rare case.
An incorrect datetime value... not as rare?
> +select * from t1;
Is the above supposed to read the EITS data? It doesn't as the query doesn't
use the WHERE clause.
> +col1
> +2004-01-01
> +2004-02-29
> +0000-10-31
> +drop table t1;
> +set @@sql_mode= @save_sql_mode;
> set use_stat_tables=@save_use_stat_tables;
> +set @@histogram_size= @save_histogram_size;
> +set
> @@optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
> set optimizer_switch=@save_optimizer_switch_for_stat_tables_test;
> SET SESSION STORAGE_ENGINE=DEFAULT;
> diff --git a/mysql-test/t/stat_tables.test b/mysql-test/t/stat_tables.test
> index b89ab2bbd2d..114c5c97a7e 100644
> --- a/mysql-test/t/stat_tables.test
> +++ b/mysql-test/t/stat_tables.test
> @@ -401,4 +401,44 @@ SELECT MAX(pk) FROM t1;
>
> DROP TABLE t1;
>
> +--echo #
> +--echo # MDEV-18899: Server crashes in
> Field::set_warning_truncated_wrong_value
> +--echo #
> +
> +set names utf8;
> +set
> @save_optimizer_use_condition_selectivity=@@optimizer_use_condition_selectivity;
> +set optimizer_use_condition_selectivity=4;
> +set use_stat_tables=preferably;
> +set @save_histogram_size= @@histogram_size;
> +set histogram_size=255;
> +
> +create table t1 ( a varchar(255) character set utf8);
> +insert into t1 values (REPEAT('ӥ',255)), (REPEAT('ç',255));
> +
> +analyze table t1;
> +select HEX(RIGHT(min_value, 1)), length(min_value) from mysql.column_stats;
> +select HEX(RIGHT(max_value, 1)), length(max_value) from mysql.column_stats;
> +analyze select * from t1 where a >= 'ӥ';
> +
> +set @save_sql_mode= @@sql_mode;
> +set
> sql_mode='ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
> +update mysql.column_stats set min_value= REPEAT('ӥ',255);
> +select HEX(RIGHT(min_value, 1)), length(min_value) from mysql.column_stats;
> +analyze select * from t1 where a >= 'ӥ';
> +
> +set names latin1;
> +drop table t1;
> +
> +CREATE TABLE t1 (col1 date);
> +INSERT INTO t1 VALUES('2004-01-01'),('2004-02-29');
> +INSERT INTO t1 VALUES('0000-10-31');
> +analyze table t1;
> +update mysql.column_stats set min_value='2004-0-31123';
> +select min_value from mysql.column_stats;
> +select * from t1;
> +drop table t1;
> +
> +set @@sql_mode= @save_sql_mode;
> set use_stat_tables=@save_use_stat_tables;
> +set @@histogram_size= @save_histogram_size;
> +set
> @@optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
> diff --git a/sql/field.cc b/sql/field.cc
> index 080cf34c76d..c26195a3650 100644
> --- a/sql/field.cc
> +++ b/sql/field.cc
> @@ -2219,7 +2219,6 @@ bool Field_str::can_be_substituted_to_equal_item(const
> Context &ctx,
> return false;
> }
>
> -
> void Field_num::make_field(Send_field *field)
> {
> Field::make_field(field);
> @@ -7023,12 +7022,16 @@ Field_longstr::check_string_copy_error(const
> String_copier *copier,
> {
> const char *pos;
> char tmp[32];
> + THD *thd= get_thd();
>
> if (!(pos= copier->most_important_error_pos()))
> return FALSE;
>
> - convert_to_printable(tmp, sizeof(tmp), pos, (end - pos), cs, 6);
> - set_warning_truncated_wrong_value("string", tmp);
> + if (thd->count_cuted_fields)
> + {
> + convert_to_printable(tmp, sizeof(tmp), pos, (end - pos), cs, 6);
> + set_warning_truncated_wrong_value("string", tmp);
> + }
> return TRUE;
> }
>
> diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
> index b5811c683e8..0960a9a1ec5 100644
> --- a/sql/sql_statistics.cc
> +++ b/sql/sql_statistics.cc
> @@ -1044,6 +1044,7 @@ class Column_stat: public Stat_table
> {
> char buff[MAX_FIELD_WIDTH];
> String val(buff, sizeof(buff), &my_charset_bin);
> + uint32 length= 0;
>
> for (uint i= COLUMN_STAT_MIN_VALUE; i <= COLUMN_STAT_HISTOGRAM; i++)
> {
> @@ -1060,7 +1061,9 @@ class Column_stat: public Stat_table
> else
> {
> table_field->collected_stats->min_value->val_str(&val);
> - stat_field->store(val.ptr(), val.length(), &my_charset_bin);
> + length= Well_formed_prefix(val.charset(), val.ptr(),
> + MY_MIN(val.length(),
> stat_field->field_length)).length();
> + stat_field->store(val.ptr(), length, &my_charset_bin);
> }
> break;
> case COLUMN_STAT_MAX_VALUE:
> @@ -1069,7 +1072,9 @@ class Column_stat: public Stat_table
> else
> {
> table_field->collected_stats->max_value->val_str(&val);
> - stat_field->store(val.ptr(), val.length(), &my_charset_bin);
> + length= Well_formed_prefix(val.charset(), val.ptr(),
> + MY_MIN(val.length(),
> stat_field->field_length)).length();
> + stat_field->store(val.ptr(), length, &my_charset_bin);
> }
> break;
> case COLUMN_STAT_NULLS_RATIO:
> @@ -2934,7 +2939,6 @@ int update_statistics_for_table(THD *thd, TABLE *table)
> DBUG_RETURN(rc);
> }
>
> -
> /**
> @brief
> Read statistics for a table from the persistent statistical tables
> @@ -2980,6 +2984,7 @@ int read_statistics_for_table(THD *thd, TABLE *table,
> TABLE_LIST *stat_tables)
> Table_statistics *read_stats= table_share->stats_cb.table_stats;
>
> DBUG_ENTER("read_statistics_for_table");
> + DBUG_ASSERT(thd->count_cuted_fields == CHECK_FIELD_IGNORE);
>
> /* Read statistics from the statistical table table_stats */
> stat_table= stat_tables[TABLE_STAT].table;
> @@ -3059,7 +3064,7 @@ int read_statistics_for_table(THD *thd, TABLE *table,
> TABLE_LIST *stat_tables)
> }
> }
> }
> -
> +
> table->stats_is_read= TRUE;
>
> DBUG_RETURN(0);
BR
Sergei
--
Sergei Petrunia, Software Developer
MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog
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