11
22 Frequently Asked Questions (FAQ) for PostgreSQL
33
4- Last updated:Wed Oct9 23:14:53 EDT 2002
4+ Last updated:Fri Oct11 00:59:31 EDT 2002
55
66 Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
77
9696 4.25) How do I return multiple rows or columns from a function?
9797 4.26) Why can't I reliably create/drop temporary tables in PL/PgSQL
9898 functions?
99+ 4.27) What replication options are available?
100+ 4.28) What encryption options are available?
99101
100102 Extending PostgreSQL
101103
@@ -1046,12 +1048,13 @@ SELECT *
10461048
10471049 4.24) How do I perform queries using multiple databases?
10481050
1049- There is no way to queryany databaseexcept the current one. Because
1050- PostgreSQL loads database-specific system catalogs, it is uncertain
1051- how a cross-database query should even behave.
1051+ There is no way to querya databaseother than the current one.
1052+ Because PostgreSQL loads database-specific system catalogs, it is
1053+ uncertain how a cross-database query should even behave.
10521054
1053- Of course, a client can make simultaneous connections to different
1054- databases and merge the information that way.
1055+ /contrib/dblink allows cross-database queries using function calls. Of
1056+ course, a client can make simultaneous connections to different
1057+ databases and merge the results on the client side.
10551058
10561059 4.25) How do I return multiple rows or columns from a function?
10571060
@@ -1070,6 +1073,25 @@ SELECT *
10701073 the old temporary table. The solution is to use EXECUTE for temporary
10711074 table access in PL/PgSQL. This will cause the query to be reparsed
10721075 every time.
1076+
1077+ 4.27) What replication options are available?
1078+
1079+ There are several master/slave replication solutions available. These
1080+ allow only the master to make database changes and the slave can only
1081+ do database reads. The bottom of
1082+ http://gborg.postgresql.org/genpage?replication_research lists them. A
1083+ multi-master replication solution is being worked on at
1084+ http://gborg.postgresql.org/project/pgreplication/projdisplay.php.
1085+
1086+ 4.27) What encryption options are available?
1087+
1088+ * /contrib/pgcrypto contains many encryption functions for use in
1089+ SQL queries.
1090+ * The only way to encrypt transmission from the client to the server
1091+ is by using hostssl in pg_hba.conf.
1092+ * Database user passwords are automatically encrypted when stored in
1093+ version 7.3. In previous versions, you must enable
1094+ password_encryption in postgresql.conf.
10731095 _________________________________________________________________
10741096
10751097 Extending PostgreSQL