From 9aac62305b13a5cf7e8ded2020ffca25f9d666be Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Mon, 10 Jun 2002 19:47:57 +0000
Subject: [PATCH] Add item for plpgsql temp table access.
---
doc/FAQ | 15 ++++++++++++++-
doc/src/FAQ/FAQ.html | 41 ++++++++++++++++++++++++++---------------
2 files changed, 40 insertions(+), 16 deletions(-)
diff --git a/doc/FAQ b/doc/FAQ
index 2c4193a833d..c8889819495 100644
--- a/doc/FAQ
+++ b/doc/FAQ
@@ -1,7 +1,7 @@
Frequently Asked Questions (FAQ) for PostgreSQL
- Last updated: Fri Apr 26 23:03:46 EDT 2002
+ Last updated: Mon Jun 10 15:47:38 EDT 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@@ -92,6 +92,8 @@
4.23) How do I perform an outer join?
4.24) How do I perform queries using multiple databases?
4.25) How do I return multiple rows or columns from a function?
+ 4.26) Why can't I reliably create/drop temporary tables in PL/PgSQL
+ functions?
Extending PostgreSQL
@@ -1031,6 +1033,17 @@ SELECT *
http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html,
section 23.7.3.3.
+ 4.26) Why can't I reliably create/drop temporary tables in PL/PgSQL
+ functions?
+
+ PL/PgSQL caches function contents, and an unfortunate side effect is
+ that if a PL/PgSQL function accesses a temporary table, and that table
+ is later dropped and recreated, and the function called again, the
+ function will fail because the cached function contents still point to
+ the old temporary table. The solution is to use EXECUTE for temporary
+ table access in PL/PgSQL. This will cause the query to be reparsed
+ every time.
+
Extending PostgreSQL
5.1) I wrote a user-defined function. When I run it in psql, why does it
diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html
index 988aa3f968f..8ca6cd9c454 100644
--- a/doc/src/FAQ/FAQ.html
+++ b/doc/src/FAQ/FAQ.html
@@ -14,7 +14,7 @@
alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
- <P>Last updated: Fri Apr 26 23:03:46 EDT 2002</P>
+ <P>Last updated: Mon Jun 10 15:47:38 EDT 2002</P>
<P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
@@ -138,7 +138,9 @@
<A href="#4.24">4.24</A>) How do I perform queries using multiple
databases?<BR>
<A href="#4.25">4.25</A>) How do I return multiple rows or columns
- from a function?<BR>
+ from a function?<BR>
+ <A href="#4.26">4.26</A>) Why can't I reliably create/drop
+ temporary tables in PL/PgSQL functions?<BR>
<H2 align="center">Extending PostgreSQL</H2>
@@ -742,7 +744,7 @@
<P>You can also compile with profiling to see what functions are
taking execution time. The backend profile files will be deposited
in the <I>pgsql/data/base/dbname</I> directory. The client profile
- file will be put in the client's current directory. Linux requires
+ file will be put in the client's current directory. Linux requires
a compile with <I>-DLINUX_PROFILE</I> for proper profiling.</P>
<H4><A name="3.8">3.8</A>) Why do I get <I>"Sorry, too many
@@ -900,9 +902,9 @@
databases, and users are defined?</H4>
<P><I>psql</I> has a variety of backslash commands to show such
- information. Use \? to see them. There are also system tables
- beginning with <i>pg_</i> that describe these too. Also, <i>psql
- -l</i> will list all databases.</P>
+ information. Use \? to see them. There are also system tables
+ beginning with <I>pg_</I> that describe these too. Also, <I>psql
+ -l</I> will list all databases.</P>
<P>Also try the file <I>pgsql/src/tutorial/syscat.source</I>. It
illustrates many of the <SMALL>SELECT</SMALL>s needed to get
@@ -1307,16 +1309,25 @@ BYTEA bytea variable-length byte array (null-byte safe)
different databases and merge the information that way.</P>
<HR>
- <H4><A name="4.25">4.25</A>) How do I return multiple rows or columns
- from a function?</H4>
+ <H4><A name="4.25">4.25</A>) How do I return multiple rows or
+ columns from a function?</H4>
+
+ <P>You can return result sets from PL/pgSQL functions using
+ <I>refcursors</I>. See <A href=
+ "http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html">
+ http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html,</A>
+ section 23.7.3.3.</P>
+
+ <H4><A href="#4.26">4.26</A>) Why can't I reliably create/drop
+ temporary tables in PL/PgSQL functions?</H4>
+ PL/PgSQL caches function contents, and an unfortunate side effect
+ is that if a PL/PgSQL function accesses a temporary table, and that
+ table is later dropped and recreated, and the function called
+ again, the function will fail because the cached function contents
+ still point to the old temporary table. The solution is to use
+ <SMALL>EXECUTE</SMALL> for temporary table access in PL/PgSQL. This
+ will cause the query to be reparsed every time.
- <P>You can return result sets from PL/pgSQL functions using
- <i>refcursors</i>. See <a
- href="http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html">
- http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html,</a>
- section 23.7.3.3.</P>
-
-
<H2 align="center">Extending PostgreSQL</H2>
<H4><A name="5.1">5.1</A>) I wrote a user-defined function. When I
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