- developers - lists.mariadb.org

[Maria-developers] galera source and direction
by Daniel Black 09 May '17

09 May '17

With Codership's galera repository showing spelling fixes and test case changes as the only changes this year, and Percona's galera repository streaming ahead with improvements, is Percona's galera becoming the new base? I did a quick test though and the mtr tests all pass with Percona's galera on the 10.2 branch head.

1 0

[Maria-developers] Google Summer of Code 2017 students
by Daniel Black 05 May '17

05 May '17

Folks I'd like to welcome our Google Summer of Code students. https://summerofcode.withgoogle.com/organizations/5889423829893120/#projects Ankit Kumar - Allow multiple alternative authentication methods for the same user mentor: Sergei Golubchik Daniil Medvedev - Full DECIMAL support in ColumnStore mentor: Andrew Hutchings Sumit Lakra - NUMA GSoC Project Proposal mentors: Daniel Black and Jan Lindström Galina Shalygina - Transformation of IN predicate into IN subquery based on implementation of table value constructor mentor: Igor Babaev Please make them welcome and we are looking forward to mentoring them to develop their contributions.

1 0

[Maria-developers] MDEV-7049 MySQL#74585 - InnoDB: Failing assertion: *mbmaxlen < 5 in file ha_innodb.cc line 1904
by Alexander Barkov 04 May '17

04 May '17

Hello Marko, InnoDB uses 5 bits to store the combination of mbminlen and mbmaxlen, and its calculated as: mbmaxlen * 5 + mbminlen Note, combinations with mbminlen=0 and mbmaxlen=0 are not possible. Also, combinations with mbminlen>mbmaxlen are not possible. This is a summary: mbminlen mbmaxlen 0 1 2 3 4 0 (0) (1) (2) (3) (4) 1 (5) 6 (7) (8) (9) 2 (10) 11 12 (13) (14) 3 (15) 16 17 18 (19) 4 (20) 21 22 23 24 I marked impossible numbers with parentheses. In the range 0..24: - 10 pairs are valid - 15 pairs are not valid It should be safe to use any impossible number to mean mbmaxlen=5 & mbminlen=1 It seems there is no really a need to extend the header to use separate 3 bits for both mbminlen and mbmaxlen.

2 2

[Maria-developers] MDEV-10142 - bb-10.2-compatibility
by jerome brauge 04 May '17

04 May '17

Hello Alexander, This is the patch for CHR(). Function CHR(n) returns the character having the binary equivalent to n in the database character set. Returns null on null input. Regard, Jérôme. PS : I share this code under terms of MCA. > -----Message d'origine----- > De : Alexander Barkov [mailto:bar@mariadb.org] > Envoyé : mercredi 26 avril 2017 06:12 > À : jerome brauge > Cc : MariaDB Developers > Objet : Re: MDEV-10142 - bb-10.2-compatibility / MDEV-10574 > > Hello Jerome, > > Thanks for working on this! > > On 04/25/2017 11:42 PM, jerome brauge wrote: > > Hello Alexander, > > Some times ago, we have had the below discussion. > > I made a patch following my first idea (it's enough from our point of view) : > replace empty string by null in literals and in make_empty_string. > > I think this patch can be complementary to your suggestion of adding > > an Item_func_eq_oracle (for data inserted in default sql_mode) > > > > This patch also contains following some functions changes: > > - replace ('ab','a',null) returns 'a' instead null > > - trim / ltrim / rtrim returns null when input only contains spaces > > - lpad /rpad can accept 2 args (default padding char is space) and if > > length equals to 0, returns null -substring : if start index is equal > > to 0, act as if it's equals to 1 -add a function chr() as a synonym of > > char() (but accept only one arg) -add a function lengthb() as a > > synonym of lentgh() -change the semantic of length for oracle (where > > length() is the character length and not the byte length) > > > > What do you think about this patch ? > > > > (Perhaps I have to make 2 patchs, one for empty string, and one for > > functions changes with separate test file for each modified function) > > Right, can you please split the patch into pieces? > I suggest even more pieces than two. One patch for one function. > I'll create MDEVs, one MDEV per function and put examples how Oracle > works. > > Can we do it in the following order: > > 1. LPAD / RPAD - making the third parameter optional. > This extension will be good for all sql_modes. > I checked IBM DB2, Oracle PostgreSQL, Firebird - they all have > the third parameter to LPAD/RPAD optional. > > 2. CHR(). > > 3. LENGTH() and LENGTHB(). > > > Then we can continue with REPLACE, TRIM. SUBSTRING in no particular > order, one patch per function. > > > Some general notes: > > > 1. Unify *.yy files > > Please put sql_mode dependent code into LEX rather than *.yy files directly. > We're going to unify the two files soon. See here for details: > MDEV-12518) Unify sql_yacc.yy and sql_yacc_ora.yy > > So instead of doing: > > | SUBSTRING '(' expr ',' expr ',' expr ')' > { > $$= new (thd->mem_root) Item_func_substr(thd, $3, $5, $7); > if ($$ == NULL) > MYSQL_YYABORT; > } > > > Please do something like this in both sql_yacc.yy and sql_yacc_ora.yy: > > > | SUBSTRING '(' expr ',' expr ',' expr ')' > { > if (!($$= Lex->make_item_func_substr(thd, $3, $5, $7))) > MYSQL_YYABORT; > } > > where LEX::make_item_func_substr() is a new method, creating either > Item_func_substr or Item_func_substr_oracle depending on sql_mode. > > The same applies to all other functions, and to text_literal. > > > 2. Don't use Item::is_null() when you call val_str() anyway. > > There are two reasons that: > - Performance > is_null() involves the second val_str() call, which can be resource consuming > in case of complex functions and subselect. > > - Side effect > Expressions can have some side effects. > For example, in case if the argument is a stored function which counts how > many times it was called and stores the counter in a user variable, or writes > something to a table on every execution. > If we do is_null() followed by val_str(), the side effect will done two times. > We need one time only. > > So instead of: > > String *Item_func_replace_oracle::val_str(String *str) { > String * res; > if (res = replace_value(str, > args[1]->is_null() ? &tmp_emtpystr : > rgs[1]->val_str(&tmp_value2), > args[2]->is_null() ? &tmp_emtpystr : > rgs[2]->val_str(&tmp_value3)) > > return (res->length() == 0) ? make_empty_result () : res; > else > return 0; > } > > > Please do something like this: > > String *Item_func_replace_oracle::val_str(String *str) { > String * res; > String *str1= args[1]->val_str(&tmp_value1); > String *str2= args[2]->val_str(&tmp_value2); > if (res= replace_value(str, > str1 ? str1 : &tmp_emptystr, > str2 ? str2 : &tmp_emptystr) > return (res->length() == 0) ? make_empty_result () : res; > else > return 0; > } > > > Thanks! > > > > > > > Best regards, > > Jérôme. > > > >> -----Message d'origine----- > >> De : Alexander Barkov [mailto:bar@mariadb.org] Envoyé : lundi 23 > >> janvier 2017 12:49 À : jerome brauge Cc : MariaDB Developers Objet : > >> Re: MDEV-10142 - bb-10.2-compatibility / MDEV-10574 > >> > >> Hi Jerome, > >> > >> On 01/18/2017 01:22 PM, jerome brauge wrote: > >>> Hello Alexander, > >>> Sometime ago, when I ask you about plan for MDEV-10574, you replied : > >>> > >>>> The current plan is to do these transformations: > >>>> > >>>> 1. Transform Insert > >>>> - insert values ("") -> insert values (null) > >>>> > >>>> 2. Transform Select > >>>> > >>>> - where v=x => (v <> "" and V=X) > >>>> - where v is null => (v="" or v is null) > >>>> > >>>> We didn't plan to change functions yet. Thanks for bringing this up. > >>>> We'll discuss this. > >>> > >>> I've done some tests just by changing : > >>> - insert an Item_null instead of an Item_string when $1.length==0 in > >>> rule text_literal of sql_yacc_ora.yy > >>> - return null instead of an empty string in > >>> Item_str_func::make_empty_result > >>> > >>> My first tests seem promising. > >>> > >>> Of course this solution does not allow to "see" the records created > >>> with > >> empty strings as null values. > >>> I don't see the importance of being able to do this in a transparent way. > >>> We can explicitly select these row by adding rtrim on these columns. > >>> > >>> If you are interesting, I can begin to write a test to evaluate the > >>> coverage of > >> this solution. > >> > >> I'm afraid this will fix the behavior only for literals. > >> > >> This script: > >> > >> DROP TABLE t1; > >> CREATE TABLE t1 (a VARCHAR(10), b VARCHAR(10)); INSERT INTO t1 > VALUES > >> ('',''); SELECT COUNT(*) FROM t1 WHERE a=''; SELECT COUNT(*) FROM t1 > >> WHERE a=b; > >> > >> returns 0 for both SELECT queries in Oracle, and returns 1 for both > >> SELECT queries in MariaDB, Your approach will fix the first SELECT only. > >> The second will still return 1. > >> > >> > >> For now, I'm not sure how to do this correctly. Some ways possible: > >> > >> 1. We could add new classes, e.g. Item_func_eq_oracle as a pair for > >> Item_func_eq, which will handle both empty strings and NULLs inside > >> their > >> val_int() implementations. > >> > >> 2. Or there could be some after-processing on the created Item tree > >> which will replace all things like Item_func_eq to Item_cond_and with > >> Item_func_eq and Item_func_null_predicate passed as arguments. > >> > >> Currently I'm inclined to #1, because we don't have a good mechanism > >> to clone items to implement #2 correctly. We'd need such cloning to > >> pass arguments both to Item_func_eq and Item_func_null_predicate > correctly. > >> Some places in the code don't expect that the same arguments can be > >> passed to two different Item_func instances. > >> > >> On the other hand, implementing #1 will need more changes in the > >> optimizer. > >> > >> We were going to think on this later. > >> > >>> > >>> Best regard. > >>> Jérôme. > >>>

2 6

[Maria-developers] cte page
by Galina Shalygina 04 May '17

04 May '17

мои артиклы

4 5

[Maria-developers] Please review a patch for MDEV-12665 Hybrid functions do not preserve geometry type
by Alexander Barkov 02 May '17

02 May '17

Hello Alexey, Please review a joint patch fixing these two problems: MDEV-12665 Hybrid functions do not preserve geometry type MDEV-12560 Wrong data type for SELECT NULL UNION SELECT Point(1,1) Thanks!

1 0

[Maria-developers] Race Condition in Seconds behind master.
by Sachin Setiya 02 May '17

02 May '17

Hello Everyone! I setup a classical master-slave server. Master is constantly running query like this insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); flush logs; insert into t1 values(1,1,1,1,1); {there are arround million querys} Then I executed Show slave status (couple of times in a second), and found Seconds_behind_master is changing arbitrarily MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014595 Read_Master_Log_Pos: 4 Relay_Log_File: slave-relay-bin.029186 Relay_Log_Pos: 3557 Relay_Master_Log_File: master-bin.014593 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 3257 Relay_Log_Space: 184375 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 148 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-145942 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Reading event from the relay log 1 row in set (0.01 sec) MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014632 Read_Master_Log_Pos: 3257 Relay_Log_File: slave-relay-bin.029264 Relay_Log_Pos: 1548 Relay_Master_Log_File: master-bin.014632 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 1248 Relay_Log_Space: 179996 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-146322 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: init 1 row in set (0.00 sec) MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014670 Read_Master_Log_Pos: 299 Relay_Log_File: slave-relay-bin.029336 Relay_Log_Pos: 3557 Relay_Master_Log_File: master-bin.014668 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 3257 Relay_Log_Space: 184569 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 150 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-146692 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Reading event from the relay log -- Regards Sachin Setiya Software Engineer at MariaDB

3 2

[Maria-developers] bb-10.2-ext / rpad lpad with 2 args
by jerome brauge 02 May '17

02 May '17

Hi Alexander, This is the patch for rpad/lpad with 2 args (call of make_empty_string() in val_str() is to prepare MDEV-10574). Regard, Jérôme. PS : I share this code under terms of MCA. > -----Message d'origine----- > De : Alexander Barkov [mailto:bar@mariadb.org] > Envoyé : mercredi 26 avril 2017 06:12 > À : jerome brauge > Cc : MariaDB Developers > Objet : Re: MDEV-10142 - bb-10.2-compatibility / MDEV-10574 > > Hello Jerome, > > Thanks for working on this! > > On 04/25/2017 11:42 PM, jerome brauge wrote: > > Hello Alexander, > > Some times ago, we have had the below discussion. > > I made a patch following my first idea (it's enough from our point of view) : > replace empty string by null in literals and in make_empty_string. > > I think this patch can be complementary to your suggestion of adding > > an Item_func_eq_oracle (for data inserted in default sql_mode) > > > > This patch also contains following some functions changes: > > - replace ('ab','a',null) returns 'a' instead null > > - trim / ltrim / rtrim returns null when input only contains spaces > > - lpad /rpad can accept 2 args (default padding char is space) and if > > length equals to 0, returns null -substring : if start index is equal > > to 0, act as if it's equals to 1 -add a function chr() as a synonym of > > char() (but accept only one arg) -add a function lengthb() as a > > synonym of lentgh() -change the semantic of length for oracle (where > > length() is the character length and not the byte length) > > > > What do you think about this patch ? > > > > (Perhaps I have to make 2 patchs, one for empty string, and one for > > functions changes with separate test file for each modified function) > > Right, can you please split the patch into pieces? > I suggest even more pieces than two. One patch for one function. > I'll create MDEVs, one MDEV per function and put examples how Oracle > works. > > Can we do it in the following order: > > 1. LPAD / RPAD - making the third parameter optional. > This extension will be good for all sql_modes. > I checked IBM DB2, Oracle PostgreSQL, Firebird - they all have > the third parameter to LPAD/RPAD optional. > > 2. CHR(). > > 3. LENGTH() and LENGTHB(). > > > Then we can continue with REPLACE, TRIM. SUBSTRING in no particular > order, one patch per function. > > > Some general notes: > > > 1. Unify *.yy files > > Please put sql_mode dependent code into LEX rather than *.yy files directly. > We're going to unify the two files soon. See here for details: > MDEV-12518) Unify sql_yacc.yy and sql_yacc_ora.yy > > So instead of doing: > > | SUBSTRING '(' expr ',' expr ',' expr ')' > { > $$= new (thd->mem_root) Item_func_substr(thd, $3, $5, $7); > if ($$ == NULL) > MYSQL_YYABORT; > } > > > Please do something like this in both sql_yacc.yy and sql_yacc_ora.yy: > > > | SUBSTRING '(' expr ',' expr ',' expr ')' > { > if (!($$= Lex->make_item_func_substr(thd, $3, $5, $7))) > MYSQL_YYABORT; > } > > where LEX::make_item_func_substr() is a new method, creating either > Item_func_substr or Item_func_substr_oracle depending on sql_mode. > > The same applies to all other functions, and to text_literal. > > > 2. Don't use Item::is_null() when you call val_str() anyway. > > There are two reasons that: > - Performance > is_null() involves the second val_str() call, which can be resource consuming > in case of complex functions and subselect. > > - Side effect > Expressions can have some side effects. > For example, in case if the argument is a stored function which counts how > many times it was called and stores the counter in a user variable, or writes > something to a table on every execution. > If we do is_null() followed by val_str(), the side effect will done two times. > We need one time only. > > So instead of: > > String *Item_func_replace_oracle::val_str(String *str) { > String * res; > if (res = replace_value(str, > args[1]->is_null() ? &tmp_emtpystr : > rgs[1]->val_str(&tmp_value2), > args[2]->is_null() ? &tmp_emtpystr : > rgs[2]->val_str(&tmp_value3)) > > return (res->length() == 0) ? make_empty_result () : res; > else > return 0; > } > > > Please do something like this: > > String *Item_func_replace_oracle::val_str(String *str) { > String * res; > String *str1= args[1]->val_str(&tmp_value1); > String *str2= args[2]->val_str(&tmp_value2); > if (res= replace_value(str, > str1 ? str1 : &tmp_emptystr, > str2 ? str2 : &tmp_emptystr) > return (res->length() == 0) ? make_empty_result () : res; > else > return 0; > } > > > Thanks! > > > > > > > Best regards, > > Jérôme. > > > >> -----Message d'origine----- > >> De : Alexander Barkov [mailto:bar@mariadb.org] Envoyé : lundi 23 > >> janvier 2017 12:49 À : jerome brauge Cc : MariaDB Developers Objet : > >> Re: MDEV-10142 - bb-10.2-compatibility / MDEV-10574 > >> > >> Hi Jerome, > >> > >> On 01/18/2017 01:22 PM, jerome brauge wrote: > >>> Hello Alexander, > >>> Sometime ago, when I ask you about plan for MDEV-10574, you replied : > >>> > >>>> The current plan is to do these transformations: > >>>> > >>>> 1. Transform Insert > >>>> - insert values ("") -> insert values (null) > >>>> > >>>> 2. Transform Select > >>>> > >>>> - where v=x => (v <> "" and V=X) > >>>> - where v is null => (v="" or v is null) > >>>> > >>>> We didn't plan to change functions yet. Thanks for bringing this up. > >>>> We'll discuss this. > >>> > >>> I've done some tests just by changing : > >>> - insert an Item_null instead of an Item_string when $1.length==0 in > >>> rule text_literal of sql_yacc_ora.yy > >>> - return null instead of an empty string in > >>> Item_str_func::make_empty_result > >>> > >>> My first tests seem promising. > >>> > >>> Of course this solution does not allow to "see" the records created > >>> with > >> empty strings as null values. > >>> I don't see the importance of being able to do this in a transparent way. > >>> We can explicitly select these row by adding rtrim on these columns. > >>> > >>> If you are interesting, I can begin to write a test to evaluate the > >>> coverage of > >> this solution. > >> > >> I'm afraid this will fix the behavior only for literals. > >> > >> This script: > >> > >> DROP TABLE t1; > >> CREATE TABLE t1 (a VARCHAR(10), b VARCHAR(10)); INSERT INTO t1 > VALUES > >> ('',''); SELECT COUNT(*) FROM t1 WHERE a=''; SELECT COUNT(*) FROM t1 > >> WHERE a=b; > >> > >> returns 0 for both SELECT queries in Oracle, and returns 1 for both > >> SELECT queries in MariaDB, Your approach will fix the first SELECT only. > >> The second will still return 1. > >> > >> > >> For now, I'm not sure how to do this correctly. Some ways possible: > >> > >> 1. We could add new classes, e.g. Item_func_eq_oracle as a pair for > >> Item_func_eq, which will handle both empty strings and NULLs inside > >> their > >> val_int() implementations. > >> > >> 2. Or there could be some after-processing on the created Item tree > >> which will replace all things like Item_func_eq to Item_cond_and with > >> Item_func_eq and Item_func_null_predicate passed as arguments. > >> > >> Currently I'm inclined to #1, because we don't have a good mechanism > >> to clone items to implement #2 correctly. We'd need such cloning to > >> pass arguments both to Item_func_eq and Item_func_null_predicate > correctly. > >> Some places in the code don't expect that the same arguments can be > >> passed to two different Item_func instances. > >> > >> On the other hand, implementing #1 will need more changes in the > >> optimizer. > >> > >> We were going to think on this later. > >> > >>> > >>> Best regard. > >>> Jérôme. > >>>

2 4

[Maria-developers] MDEV-12617 CASE and CASE-alike hybrid functions do not preserve exact data types
by Alexander Barkov 28 Apr '17

28 Apr '17

Hi Sanja, can you please review a patch for MDEV-12617? Thanks!

1 0

[Maria-developers] MDEV-10142 - bb-10.2-compatibility / MDEV-10574
by jerome brauge 28 Apr '17

28 Apr '17

Hello Alexander, Sometime ago, when I ask you about plan for MDEV-10574, you replied : >The current plan is to do these transformations: > >1. Transform Insert >- insert values ("") -> insert values (null) > >2. Transform Select > >- where v=x => (v <> "" and V=X) >- where v is null => (v="" or v is null) > >We didn't plan to change functions yet. Thanks for bringing this up. >We'll discuss this. I've done some tests just by changing : - insert an Item_null instead of an Item_string when $1.length==0 in rule text_literal of sql_yacc_ora.yy - return null instead of an empty string in Item_str_func::make_empty_result My first tests seem promising. Of course this solution does not allow to "see" the records created with empty strings as null values. I don't see the importance of being able to do this in a transparent way. We can explicitly select these row by adding rtrim on these columns. If you are interesting, I can begin to write a test to evaluate the coverage of this solution. Best regard. Jérôme.

2 6