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

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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()
This commit is contained in:
unknown 2006-07-10 19:50:40 -07:00
parent 66fc547d1b
commit 8dc1fa1cf1
3 changed files with 43 additions and 1 deletions
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28
mysql-test/r/func_compress.result
View file

@ -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

14
mysql-test/t/func_compress.test
View file

@ -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

2
sql/item_strfunc.h
View file

@ -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
};