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Update FAQ.
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doc/FAQ
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doc/FAQ
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Features
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Features
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PostgreSQL has most features present in large commercial
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PostgreSQL has most features present in large commercial
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DBMS's, like transactions, subselects, triggers, views, and
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DBMS's, like transactions, subselects, triggers, views, foreign
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sophisticated locking. We have some features they don't have,
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key referential integrity, and sophisticated locking. We have
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like user-defined types, inheritance, rules, and multi-version
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some features they don't have, like user-defined types,
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concurrency control to reduce lock contention. We don't have
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inheritance, rules, and multi-version concurrency control to
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foreign key referential integrity or outer joins, but are
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reduce lock contention. We don't have outer joins, but are
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working on them for our next release.
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working on them for our next release.
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Performance
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Performance
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@ -396,10 +396,10 @@
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2.1) Are there ODBC drivers for PostgreSQL?
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2.1) Are there ODBC drivers for PostgreSQL?
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There are two ODBC drivers available, PostODBC and OpenLink ODBC.
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There are two ODBC drivers available, PsqlODBC and OpenLink ODBC.
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PostODBC is included in the distribution. More information about it
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PsqlODBC is included in the distribution. More information about it
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can be gotten from: http://www.insightdist.com/psqlodbc
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can be gotten from: ftp://ftp.postgresql.org/pub/odbc/index.html
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OpenLink ODBC can be gotten from http://www.openlinksw.com. It works
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OpenLink ODBC can be gotten from http://www.openlinksw.com. It works
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with their standard ODBC client software so you'll have PostgreSQL
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with their standard ODBC client software so you'll have PostgreSQL
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@ -410,6 +410,8 @@
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commercial-quality support, but a freeware version will always be
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commercial-quality support, but a freeware version will always be
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available. Questions to postgres95@openlink.co.uk.
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available. Questions to postgres95@openlink.co.uk.
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See also the ODBC chapter of the Programmer's Guide.
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2.2) What tools are available for hooking PostgreSQL to Web pages?
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2.2) What tools are available for hooking PostgreSQL to Web pages?
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A nice introduction to Database-backed Web pages can be seen at:
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A nice introduction to Database-backed Web pages can be seen at:
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@ -972,12 +974,9 @@ BYTEA bytea variable-length array of bytes
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4.22) How do I create a column that will default to the current time?
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4.22) How do I create a column that will default to the current time?
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This way always works:
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Use now():
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CREATE TABLE test (x int, modtime timestamp default now() );
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CREATE TABLE test (x int, modtime timestamp default now() );
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In releases 7.0 and later, you may use:
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create table test (x int, modtime timestamp default 'now');
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4.23) Why are my subqueries using IN so slow?
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4.23) Why are my subqueries using IN so slow?
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Currently, we join subqueries to outer queries by sequential scanning
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Currently, we join subqueries to outer queries by sequential scanning
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@ -434,10 +434,10 @@ reliability, support, and price.<P>
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<DD>
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<DD>
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PostgreSQL has most features present in large commercial DBMS's, like
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PostgreSQL has most features present in large commercial DBMS's, like
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transactions, subselects, triggers, views, and sophisticated locking.
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transactions, subselects, triggers, views, foreign key referential
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We have some features they don't have, like user-defined types,
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integrity, and sophisticated locking. We have some features they don't
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inheritance, rules, and multi-version concurrency control to reduce lock
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have, like user-defined types, inheritance, rules, and multi-version
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contention. We don't have foreign key referential integrity or outer
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concurrency control to reduce lock contention. We don't have outer
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joins, but are working on them for our next release.<BR><BR>
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joins, but are working on them for our next release.<BR><BR>
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<DT> <B>Performance</B>
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<DT> <B>Performance</B>
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@ -506,11 +506,11 @@ in our BSD-style license stated above.<BR><BR>
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<H4><A NAME="2.1">2.1</A>) Are there ODBC drivers for PostgreSQL?</H4><P>
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<H4><A NAME="2.1">2.1</A>) Are there ODBC drivers for PostgreSQL?</H4><P>
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There are two ODBC drivers available, PostODBC and OpenLink ODBC.<P>
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There are two ODBC drivers available, PsqlODBC and OpenLink ODBC.<P>
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PostODBC is included in the distribution. More information about it can
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PsqlODBC is included in the distribution. More information about it can
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be gotten from: <A HREF="http://www.insightdist.com/psqlodbc">
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be gotten from: <A HREF="ftp://ftp.postgresql.org/pub/odbc/index.html">
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http://www.insightdist.com/psqlodbc</A><P>
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ftp://ftp.postgresql.org/pub/odbc/index.html</A><P>
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OpenLink ODBC can be gotten from <A HREF="http://www.openlinksw.com/">
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OpenLink ODBC can be gotten from <A HREF="http://www.openlinksw.com/">
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http://www.openlinksw.com</A>. It works with their standard ODBC client
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http://www.openlinksw.com</A>. It works with their standard ODBC client
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@ -522,6 +522,8 @@ commercial-quality support, but a freeware version will always be
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available. Questions to <A
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available. Questions to <A
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HREF="mailto:postgres95@openlink.co.uk">postgres95@openlink.co.uk</A>.<P>
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HREF="mailto:postgres95@openlink.co.uk">postgres95@openlink.co.uk</A>.<P>
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See also the <A HREF="http://www.postgresql.org/docs/programmer/odbc.htm">
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ODBC chapter of the Programmer's Guide</A>.<P>
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<H4><A NAME="2.2">2.2</A>) What tools are available for hooking
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<H4><A NAME="2.2">2.2</A>) What tools are available for hooking
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@ -1054,7 +1056,7 @@ you need to dump and reload the database, you need to use <I>pg_dump's -o</I>
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option or <SMALL>COPY WITH OIDS</SMALL> option to preserve the oids.<P>
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option or <SMALL>COPY WITH OIDS</SMALL> option to preserve the oids.<P>
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For more details, see Bruce Momjian's chapter on
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For more details, see Bruce Momjian's chapter on
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<A HREF="http://www.postgresql.org/docs/aw_pgsql_book/node74.html">Numbering Rows.</A>
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<A HREF="http://www.postgresql.org/docs/aw_pgsql_book">Numbering Rows.</A>
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<H4><A NAME="4.16.2">4.16.2</A>) How do I get the back the generated SERIAL value after an insert?</H4><P>
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<H4><A NAME="4.16.2">4.16.2</A>) How do I get the back the generated SERIAL value after an insert?</H4><P>
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Probably the simplest approach is to to retrieve the next SERIAL value from the sequence object with the <I>nextval()</I> function <I>before</I> inserting and then insert it explicitly. Using the example table in <A HREF="#4.16.1">4.16.1</A>, that might look like this:
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Probably the simplest approach is to to retrieve the next SERIAL value from the sequence object with the <I>nextval()</I> function <I>before</I> inserting and then insert it explicitly. Using the example table in <A HREF="#4.16.1">4.16.1</A>, that might look like this:
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