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From:terry jones Date:May 7 1999 1:20pm
Subject:Sparse tables in MySQL
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Can someone tell me how to do the following in MySQL, or if it is even
possible? Bear in mind that I know nothing about databases! If it
can't be done with MySQL, can it be done with other databases?

I want to create a table that is very sparse (in the sense of a sparse
matrix). Entries should be either 1 or 0, and the vast majority will
be zero. I'm wondering if there is a way to make such a table, so as
to avoid the cost various operations (adding a column is my primary
concern), without losing simplicity of access via a single SELECT.

I know I can say 'default NULL' for a column. Does this actually
allocate storage when a column or row is added? In other words, Does
it do what I want? If so, can I say SELECT ... WHERE col = 'NULL' or
something like that?

Is this a standard problem that database packages address? If not, how
would people solve it? If there's not an already-supported method, do
I have any options other than:

  - Choosing a different table design using multiple tables and break
    my single SELECT statement into something more complicated that
    joins up the appropriate tables as needed.

  - Implement sparse tables within MySQL.

Thanks for any help.

Sparse tables in MySQLterry jones7 May
  • Re: Sparse tables in MySQLMarco Becchio7 May
  • Re: Sparse tables in MySQLterry jones7 May
  • Re: Sparse tables in MySQLChristian Mack7 May
  • Re: Sparse tables in MySQLterry jones8 May
  • Re: Sparse tables in MySQLSasha Pachev8 May
  • Re: Sparse tables in MySQLterry jones10 May