Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
If I declare a bunch of fields that are not always necessary, is memory allocated for each record created or does it not allocate memory until the field is initialized?
Example: If I declare a table with an id field and a char(8) field, is memory allocated for the string each time an id is generated and entered into the table, or is it only allocated if the string is assigned a value?
The database will allocate a set memory for fields whose type size doesn’t change, such as numeric fields and
char(n). But for fields of typevarchar(n)(variable-length), for example, they will be as large as the data that is contained in them.In your example, a field type of
char(8)will allocate memory for all 8 chars. If you make the field type varchar (or nvarchar), then it will only allocate as much space as assigned to it.Can read more about mysql string types here.