Re: Count of non-null values per table column - Mailing list pgsql-general

Hello list,<br><br>Apologies if this has been asked before. My search only turned up ways to list the total non-null values for all columns as a single number. I want the count for each column by column.<br><br>I have inherited a database consisting of two related huge monolithic tables that lack referential integrity between them, or even basic data constraints. One of the problems these tables have is every single non-PK column is NULLable. I am trying to understand the information that is actually stored and used so that I can implement a (hopefully) better design. Towards that end I would like to know the count of non-null values in each column per column. In other words I would like to get the following output from a table (the numbers are totally made up):<br><br>column_name | num_values<br>------------+-----------<br>col1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5787<br>------------+-----------<br>col2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17<br>------------+-----------<br>col3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 567<br>------------+-----------<br>col4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5787<br>------------+-----------<br>col5&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 143<br>------------+-----------<br>col6&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1<br>------------+-----------<br>...<br><br>Is this possible through one or more of the system views, or will I need to write a function to do this? Obviously I can just issue multiple SELECT COUNT(column)... statements, but I'd rather not.<br><br>Thanks,<br>David