[MDEV-35379] Driver (?mariadb server) returns wrong column nullability in ResultSet - Jira

Details

Type: Bug
Status: Confirmed (View Workflow)
Priority: Major
Resolution: Unresolved
Affects Version/s: 10.5, 11.7(EOL)
Fix Version/s: 10.5
Component/s: None
Labels:
None

Description

Table schema

create table table1(idi1 int not null, idf1 int not null);

create table table2(idi2 int not null, idf2 int not null);

create table table3(idi3 int not null, idf3 int not null);

insert into table1 values(1,2);

insert into table1 values(2,3);

insert into table1 values(3,4);

Problem description

Knowledge of ResultSet column nullability is crucial for convenient developer experience (application stability too).
I looked at the driver code associated with nullability, and it seems like driver reach nullability throw network protocol.
I found simple case, where driver fails with nullability:

var pStmt = connection.prepareStatement("""

    select idi1, idi2, idi3

    from table1 t1

        left join table2 t2 on t1.idf1 = t2.idi2

        inner join table3 t3 on t2.idf2 = t3.idi3

    """);

var metaData = pStmt.getMetaData();

Assertions.assertEquals(0, metaData.isNullable(1)); // return 0

Assertions.assertEquals(0, metaData.isNullable(2)); // return 1

Assertions.assertEquals(0, metaData.isNullable(3)); // return 0

So, Oracle give correct answer.

Attachments

Activity

Sergei Golubchik added a comment - 2024-11-10 16:59

After modifying mysqltest.cc as

--- a/client/mysqltest.cc

+++ b/client/mysqltest.cc

@@ -9039,6 +9039,14 @@ void run_prepare_stmt(struct st_connection *cn, struct st_command *command,

     goto end;

+  if (display_metadata)

+  {

+    MYSQL_FIELD * STDCALL mariadb_stmt_fetch_fields(MYSQL_STMT *stmt);

+    MYSQL_FIELD *fields= mariadb_stmt_fetch_fields(stmt);

+    uint num_fields= mysql_stmt_field_count(stmt);

+    append_metadata(ds, fields, num_fields);

+  }

/*

     Get the warnings from mysql_stmt_prepare and keep them in a

     separate string

The following test

create table t1(idi1 int not null, idf1 int not null);

create table t2(idi2 int not null, idf2 int not null);

create table t3(idi3 int not null, idf3 int not null);

insert into t1 values(1,2);

insert into t1 values(2,3);

insert into t1 values(3,4);

enable_metadata;

PS_prepare select idi1, idi2, idi3 from t1 left join t2 on t1.idf1 = t2.idi2 inner join t3 on t2.idf2 = t3.idi3;

drop table t1, t2, t3;

prints N-Y-N for the "is_null" column in the metadata. If I remove "PS_prepare" part, it prints the correct N-N-N

Sergei Golubchik added a comment - 2024-11-10 16:59 After modifying mysqltest.cc as --- a/client/mysqltest.cc +++ b/client/mysqltest.cc @@ -9039,6 +9039,14 @@ void run_prepare_stmt(struct st_connection *cn, struct st_command *command, goto end; } + if (display_metadata) + { + MYSQL_FIELD * STDCALL mariadb_stmt_fetch_fields(MYSQL_STMT *stmt); + MYSQL_FIELD *fields= mariadb_stmt_fetch_fields(stmt); + uint num_fields= mysql_stmt_field_count(stmt); + append_metadata(ds, fields, num_fields); + } + /* Get the warnings from mysql_stmt_prepare and keep them in a separate string The following test create table t1(idi1 int not null , idf1 int not null ); create table t2(idi2 int not null , idf2 int not null ); create table t3(idi3 int not null , idf3 int not null ); insert into t1 values (1,2); insert into t1 values (2,3); insert into t1 values (3,4); enable_metadata; PS_prepare select idi1, idi2, idi3 from t1 left join t2 on t1.idf1 = t2.idi2 inner join t3 on t2.idf2 = t3.idi3; drop table t1, t2, t3; prints N-Y-N for the "is_null" column in the metadata. If I remove "PS_prepare" part, it prints the correct N-N-N

People

Assignee:: Dmitry Shulga

Reporter:: Gorodetskiy Dmitry

Votes:: 0 Vote for this issue

Watchers:: 2 Start watching this issue

Dates

Created:: 2024-11-10 11:30

Updated:: 2025-02-14 11:39

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