Investigating a psql error

Error messages can sometimes be cryptic, and you may be left wondering, Why did this error happen at all?

For this purpose, psql recognizes two variables, VERBOSITY and CONTEXT; valid values are terse, default, or verbose for the former, and never, errors, or always for the latter. A more verbose error message will hopefully specify extra detail, and the context information will be included. Here is an example to show the difference:

postgres=# \set VERBOSITY terse
postgres=# \set CONTEXT never
postgres=# select * from missingtable;
ERROR:  relation "missingtable" does not exist at character 15

This is quite a simple error, so we don't actually need the extra detail, but it is nevertheless useful for illustrating the extra detail you get when raising verbosity and enabling context information:

postgres=# \set VERBOSITY verbose
postgres=# \set CONTEXT errors
postgres=# select * from missingtable;
ERROR:  42P01: relation "missingtable" does not exist
LINE 1: select ...