12/9/2023 0 Comments Mysql boolean field![]() ![]() The proof of it is in the explain output, with the number of rows required to determine the answer, and the lack of a use of an index (the ref column) even on the column for both queries. So A is faster, because it is able to use the native datatype (as seen in an index that has it), and does not force a table scan due to the way B deals with the data conversion (and does cause a table scan) | 1 | SIMPLE | t123 | index | NULL | x | 1 | NULL | 3141414 | Using where Using index | | 1 | SIMPLE | t123 | ref | x | x | 1 | const | 1570707 | Using index |ī explain SELECT * FROM t123 WHERE NOT `x` | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | ![]() A explain SELECT * FROM t123 WHERE x=false Then, compare it to the value 'True' PROPOSED SOLUTION LOAD DATA LOCAL INFILE 'C:/bin/input. Understanding NULL values and their quirks and dealing with it is a "best practice".Insert t123(x) values (false),(true),(false),(true),(false),(true),(false),(true),(false),(true),(false),(true) 1 Answer Sorted by: 7 Convert the first value using user variables to load the True/False values. But those quirks are usually overcome with appropriately defined indexes and carefully written queries. We do note that there are some quirks with some database implementations, not making use of an index to satisfy a col IS NULL predicate. But in my book, "avoiding dealing with NULLs" is not a "best practice". And it's true that having a column defined as NOT NULL may somewhat ease their burden. Some set of application developers may not like (or understand) how to deal with the nuances of NULL values. The NULL and tri-valued boolean logic has been around forever (since E.F.Codd first coined "relational" in 1970, the advent of System/R and Oracle in 1977, and DB2 in 1983. It doesn't go against any "best practices" I'm aware of. Q: Is checking whether a column is NULL go against best practices? adding the (redundant) approved column flies in the face of third normal form, and the familiar mantra "Every attribute is dependent on the key, the whole key, and nothing but the key. (And we're setting aside here a discussion of redundant data and update anomalies. We can't exclude some exceptional corner case where the addition of that column would be of benefit, but in general, given the information provided, no, there's no "speed benefit" to adding that column. That would require additional blocks (space), and would add overhead for maintenance of the index entries. an index on that column would not be negligible. Boolean in MySQL is actually a tinyint with 0 being false and 1 being true, or no and yes respectively. While the additional byte for the approved column is negligible (assuming that's defined as TINYINT, that extra byte will not really impact the number of rows that "fit" in a block). 1 I dont like the enum datatype for various reasons. ![]() The schema of the table is something like this-Id varchar(36), -guid, primary key IsDirty bit(1), CreatedOn(Date), Info varchar(500) I have created a partition on CreatedOn field which creates a partition for monthly data. In this case, it's very unlikely that there would be any query would obtain a "speed benefit" from using the approved column vs approved_dttm IS NULL. I have a large MySQL table which may contain 100 million records. Q: Is there any speed benefit to using a boolean field? ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |