Commit 8dc1fa1c authored by unknown's avatar unknown
Browse files

Bug #18539: uncompress(d) is null: impossible? 

  The UNCOMPRESS() function was not marked as maybe_null, even though
  it returns NULL on invalid data. This confused the optimizer.


mysql-test/r/func_compress.result:
  Add new results
mysql-test/t/func_compress.test:
  Add new regression test
sql/item_strfunc.h:
  Set maybe_null within Item_func_uncompress::fix_length_and_dec()
parent 66fc547d

mysql-test/r/func_compress.result

+28 −0
Original line number Diff line number Diff line
@@ -79,3 +79,31 @@ uncompress(a) uncompressed_length(a) 
NULL	NULL

a	1

drop table t1;

create table t1 (a varchar(32) not null);

insert into t1 values ('foo');

explain select * from t1 where uncompress(a) is null;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	

Warnings:

Error	1256	Uncompressed data size too large; the maximum size is 104857600 (probably, length of uncompressed data was corrupted)

select * from t1 where uncompress(a) is null;

a

foo

Warnings:

Error	1256	Uncompressed data size too large; the maximum size is 104857600 (probably, length of uncompressed data was corrupted)

explain select *, uncompress(a) from t1;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	

select *, uncompress(a) from t1;

a	uncompress(a)

foo	NULL

Warnings:

Error	1256	Uncompressed data size too large; the maximum size is 104857600 (probably, length of uncompressed data was corrupted)

select *, uncompress(a), uncompress(a) is null from t1;

a	uncompress(a)	uncompress(a) is null

foo	NULL	1

Warnings:

Error	1256	Uncompressed data size too large; the maximum size is 104857600 (probably, length of uncompressed data was corrupted)

Error	1256	Uncompressed data size too large; the maximum size is 104857600 (probably, length of uncompressed data was corrupted)

drop table t1;

End of 5.0 tests

mysql-test/t/func_compress.test

+14 −0
Original line number Diff line number Diff line
@@ -57,3 +57,17 @@ select uncompress(a), uncompressed_length(a) from t1; 
drop table t1;



# End of 4.1 tests



#

# Bug #18539: uncompress(d) is null: impossible?

#

create table t1 (a varchar(32) not null);

insert into t1 values ('foo');

explain select * from t1 where uncompress(a) is null;

select * from t1 where uncompress(a) is null;

explain select *, uncompress(a) from t1;

select *, uncompress(a) from t1;

select *, uncompress(a), uncompress(a) is null from t1;

drop table t1;



--echo End of 5.0 tests

sql/item_strfunc.h

+1 −1
Original line number Diff line number Diff line
@@ -784,7 +784,7 @@ class Item_func_uncompress: public Item_str_func 
  String buffer;

public:

  Item_func_uncompress(Item *a): Item_str_func(a){}

  void fix_length_and_dec(){max_length= MAX_BLOB_WIDTH;}

  void fix_length_and_dec(){ maybe_null= 1; max_length= MAX_BLOB_WIDTH; }

  const char *func_name() const{return "uncompress";}

  String *val_str(String *) ZLIB_DEPENDED_FUNCTION

};