On Wed, Sep 30, 2020 at 7:41 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > If you really really need to do this, I'd counsel using EXECUTE to > ensure no caching happens. But I concur with Michael that it's > fundamentally a bad idea. >
Agreed, though the documentation seems a bit loose here. The fact that the temp table hides the permanent one is a side-effect of pg_temp being placed first in the default search_path. If it is explicitly placed last the permanent table would be found again. Adding a reminder that search_path searching happens only during new plan creation (even if we don't generally cover caching implementation in detail, though I didn't look around for this one) seems like a good value. I propose the following: diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index 087cad184c..a400334092 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -171,8 +171,9 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM If specified, the table is created as a temporary table. Temporary tables are automatically dropped at the end of a session, or optionally at the end of the current transaction - (see <literal>ON COMMIT</literal> below). Existing permanent - tables with the same name are not visible to the current session + (see <literal>ON COMMIT</literal> below). The default + search_path includes the temporary schema first and so identically + named existing permanent tables are not chosen for new plans while the temporary table exists, unless they are referenced with schema-qualified names. Any indexes created on a temporary table are automatically temporary as well. David J.