Still, it could be improved in a lot of ways, and the stored procedure below is a starting point. It makes use of procedure analyse (though with ‘SELECT * FROM’), and modifies it’s output to include the actual column datatype and the total number of rows of the table.

The actual datatype is a piece of information I’ve seen a lot of people request, and the number of rows is, I think, a critical piece of information to determine if the output of procedure analyse is credible or not. It’s not the same thing to take suggestions from mysql on a table with 7 or 20 rows than from a table with 1000000 rows. Of course, remember than numbers alone mean nothing, you might just have 7 rows in a table that represent the entire universe of possible values for your problem domain. In any case, a smart human being with a good toolset is the best way to solve problems!

So here’s the procedure, which can also be downloaded from this link:

/*

extended procedure analyse
(C) 2009 Fernando Ipar
mail(at)fernandoipar.com

GPLv2

*/
drop procedure if exists extended_procedure_analyse;
delimiter //
create procedure extended_procedure_analyse(databaseName varchar(64), tableName varchar(64))
begin

	create temporary table procedure_analyse_output
	(
	Field_name varchar(64),
	Min_value int,
	Max_value int,
	Min_length int,
	Max_length int,
	Empties_or_zeros int,
	Nulls int,
	Avg_value_or_avg_length float,
	Std float,
	Optimal_fieldtype text,
	Actual_fieldtype text
	);	

	set @table = concat(databaseName,'.',tableName);
	set @dbName = databaseName;
	set @tbName = tableName;

	set @qry = concat('insert into procedure_analyse_output (Field_name,Min_value,Max_value,Min_length,Max_length,Empties_or_zeros,Nulls,Avg_Value_or_avg_length,Std,Optimal_fieldtype) select * from ', @table,' procedure analyse()');
	prepare myStmt from @qry;
	execute myStmt;

	update procedure_analyse_output set Field_name = replace(Field_name,  CONCAT(databaseName,'.',tableName,'.'),'');

	prepare myStmt from 'update procedure_analyse_output pao, information_schema.columns c set pao.Actual_Fieldtype = c.column_type where table_schema = ? and table_name = ? and column_name = pao.Field_name';
	execute myStmt using @dbName,@tbName;

	set @qry = concat('select count(*) as `Total_number_of_rows` from ',@table);
	prepare myStmt from @qry;

	execute myStmt;

	select * from procedure_analyse_output;

	drop temporary table procedure_analyse_output;

end;
//
delimiter ;

Here are a couple of sample outputs:

mysql> call extended_procedure_analyse('test','City')\G
*************************** 1. row ***************************
Total_number_of_rows: 30000
1 row in set (0.11 sec)

*************************** 1. row ***************************
             Field_name: ID
              Min_value: 925001
              Max_value: 955000
             Min_length: 6
             Max_length: 6
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 940000
                    Std: 938839
      Optimal_fieldtype: MEDIUMINT(6) UNSIGNED NOT NULL
       Actual_fieldtype: int(11) unsigned
*************************** 2. row ***************************
             Field_name: CountryCode
              Min_value: 0
              Max_value: 29
             Min_length: 1
             Max_length: 2
       Empties_or_zeros: 1000
                  Nulls: 0
Avg_value_or_avg_length: 14.5
                    Std: 8.6554
      Optimal_fieldtype: ENUM('0','1','2','3','4','5','6','7','8','9','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29') NOT NULL
       Actual_fieldtype: int(11) unsigned
*************************** 3. row ***************************
             Field_name: Name
              Min_value: 1
              Max_value: 9999
             Min_length: 1
             Max_length: 5
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 4.6605
                    Std: NULL
      Optimal_fieldtype: CHAR(5) NOT NULL
       Actual_fieldtype: varchar(40)
*************************** 4. row ***************************
             Field_name: District
              Min_value: 1
              Max_value: 9999
             Min_length: 1
             Max_length: 5
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 4.6603
                    Std: NULL
      Optimal_fieldtype: CHAR(5) NOT NULL
       Actual_fieldtype: varchar(40)
*************************** 5. row ***************************
             Field_name: Population
              Min_value: 0
              Max_value: 9999
             Min_length: 1
             Max_length: 5
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 4.6647
                    Std: NULL
      Optimal_fieldtype: CHAR(5) NOT NULL
       Actual_fieldtype: varchar(40)
5 rows in set (0.12 sec)

Query OK, 0 rows affected (0.12 sec)

mysql> call extended_procedure_analyse('test','projects_innodb')\G
*************************** 1. row ***************************
Total_number_of_rows: 1007366
1 row in set (14.80 sec)

*************************** 1. row ***************************
             Field_name: id
              Min_value: 1
              Max_value: 1007366
             Min_length: 1
             Max_length: 7
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 503684
                    Std: 581599
      Optimal_fieldtype: MEDIUMINT(7) UNSIGNED NOT NULL
       Actual_fieldtype: int(10) unsigned
*************************** 2. row ***************************
             Field_name: name
              Min_value: 0
              Max_value: 9999
             Min_length: 1
             Max_length: 10
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 4.6958
                    Std: NULL
      Optimal_fieldtype: VARCHAR(10) NOT NULL
       Actual_fieldtype: char(10)
2 rows in set (14.80 sec)

Query OK, 0 rows affected (14.80 sec)

mysql> call extended_procedure_analyse('test','projects_isam')\G
*************************** 1. row ***************************
Total_number_of_rows: 1000000
1 row in set (0.56 sec)

*************************** 1. row ***************************
             Field_name: id
              Min_value: 1
              Max_value: 1000000
             Min_length: 1
             Max_length: 7
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 500000
                    Std: 577358
      Optimal_fieldtype: MEDIUMINT(7) UNSIGNED NOT NULL
       Actual_fieldtype: int(10) unsigned
*************************** 2. row ***************************
             Field_name: name
              Min_value: 0
              Max_value: 9999
             Min_length: 1
             Max_length: 5
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 4.6605
                    Std: NULL
      Optimal_fieldtype: CHAR(5) NOT NULL
       Actual_fieldtype: char(10)
2 rows in set (0.56 sec)

Query OK, 0 rows affected (0.56 sec)

Notice the difference in response time between the Innodb and MyISAM (yes, I wrongly used the ‘isam’ name …) tables, that’s because Innodb has to calculate the number of rows for a count(*) query, while MyISAM stores a row count in the table.

I plan to extend this procedure to include index information, with useful data such as overindexed columns (columns that are included as a leftmost prefix in more than one index) and unindexed columns that are queried. The first question is easily answered from information_schema.statistics, using the seq_in_index column, I’m working on the second one.

Still, if you have the time and interest, play with this early version and let me know what’s wrong and/or could be improved with it.

Related posts:

1. Extending procedure_analyse My previous post explored a stored procedure that extended procedure_analyse...
2. Indexing text columns in MySQL This time, I’m talking about indexes for string typed columns....
3. SOUNDEX(), triggers, and stored procedures MySQL provides a SOUNDEX() function, which returns the soundex of...

Related posts brought to you by Yet Another Related Posts Plugin.