rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Improvements to Ian Barwick patch.

This commit is contained in:
Bruce Momjian 2002-10-14 03:15:33 +00:00
parent 0896707ef6
commit daaf999fcb
2 changed files with 49 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
doc/FAQ
View File

@ -1,7 +1,7 @@
Frequently Asked Questions (FAQ) for PostgreSQL Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sun Oct 13 22:49:56 EDT 2002 Last updated: Sun Oct 13 23:15:09 EDT 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@ -52,7 +52,7 @@
3.6) How do I tune the database engine for better performance? 3.6) How do I tune the database engine for better performance?
3.7) What debugging features are available? 3.7) What debugging features are available?
3.8) Why do I get "Sorry, too many clients" when trying to connect? 3.8) Why do I get "Sorry, too many clients" when trying to connect?
3.9) What are the pg_sorttempNNN.NN files in my database directory? 3.9) What is in the pgsql_tmp directory?
3.10) Why do I need to do a dump and restore to upgrade PostgreSQL 3.10) Why do I need to do a dump and restore to upgrade PostgreSQL
releases? releases?
@ -197,8 +197,7 @@
distribution or the MS Windows FAQ at distribution or the MS Windows FAQ at
http://www.PostgreSQL.org/docs/faq-mswin.html. http://www.PostgreSQL.org/docs/faq-mswin.html.
A native port to some Microsoft platforms is currently being worked A native port to MS Win NT/2000/XP is currently being worked on.
upon.
1.5) Where can I get PostgreSQL? 1.5) Where can I get PostgreSQL?
@ -368,7 +367,7 @@
1.15) How can I financially assist PostgreSQL? 1.15) How can I financially assist PostgreSQL?
PostgreSQL has had a first-class infrastructure since we started in PostgreSQL has had a first-class infrastructure since we started in
1994. This is all thanks to Marc Fournier, who has created and managed 1996. This is all thanks to Marc Fournier, who has created and managed
this infrastructure over the years. this infrastructure over the years.
Quality infrastructure is very important to an open-source project. It Quality infrastructure is very important to an open-source project. It
@ -419,9 +418,9 @@
2.3) Does PostgreSQL have a graphical user interface? A report generator? 2.3) Does PostgreSQL have a graphical user interface? A report generator?
An embedded query language interface? An embedded query language interface?
We have a nice graphical user interface called PgAccess, which is We have a nice graphical user interface called PgAccess which can also
shipped as part of the distribution. PgAccess also has a report be used as a report generator. The Web page is
generator. The Web page is http://www.pgaccess.org/. http://www.pgaccess.org/.
We also include ecpg, which is an embedded SQL query language We also include ecpg, which is an embedded SQL query language
interface for C. interface for C.
@ -433,7 +432,7 @@
* C++ (libpq++) * C++ (libpq++)
* Embedded C (ecpg) * Embedded C (ecpg)
* Java (jdbc) * Java (jdbc)
* Perl (DBD::Pg) * Perl (DBD::Pg and perl5)
* ODBC (odbc) * ODBC (odbc)
* Python (PyGreSQL) * Python (PyGreSQL)
* TCL (libpgtcl) * TCL (libpgtcl)
@ -441,7 +440,8 @@
* PHP ('pg_' functions, Pear::DB) * PHP ('pg_' functions, Pear::DB)
Additional interfaces are available at Additional interfaces are available at
http://www.PostgreSQL.org/interfaces.html. http://www.PostgreSQL.org/interfaces.html and
http://gborg.PostgreSQL.org.
_________________________________________________________________ _________________________________________________________________
Administrative Questions Administrative Questions
@ -596,16 +596,16 @@
was 64, and changing it required a rebuild after altering the was 64, and changing it required a rebuild after altering the
MaxBackendId constant in include/storage/sinvaladt.h. MaxBackendId constant in include/storage/sinvaladt.h.
3.9) What are the pg_tempNNN.NN files in my database directory? 3.9) What are the pgsql_tmp directory?
They are temporary files generated by the query executor. For example, They are temporary files generated by the query executor. For example,
if a sort needs to be done to satisfy an ORDER BY, and the sort if a sort needs to be done to satisfy an ORDER BY, and the sort
requires more space than the backend's -S parameter allows, then requires more space than the backend's -S parameter allows, then
temporary files are created to hold the extra data. temporary files are created to hold the extra data.
The temporary files should be deleted automatically, but might not if The temporary files are usually deleted automatically, but might
a backend crashes during a sort. If you have no backends running at remain if a backend crashes during a sort. A stop and restart of the
the time, it is safe to delete the pg_tempNNN.NN files. postmaster will remove files from those directories.
3.10) Why do I need to do a dump and restore to upgrade between major 3.10) Why do I need to do a dump and restore to upgrade between major
PostgreSQL releases? PostgreSQL releases?
@ -649,8 +649,8 @@
4.4) How do you remove a column from a table? 4.4) How do you remove a column from a table?
Prior to version 7.3, ALTER TABLE DROP COLUMN is not supported. You This functionality was added in release 7.3 with ALTER TABLE DROP
can do this instead: COLUMN. In earlier versions, you can do this:
BEGIN; BEGIN;
LOCK TABLE old_table; LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove SELECT ... -- select all columns but the one you want to remove
@ -815,11 +815,11 @@
Case-insensitive equality comparisons are normally expressed as: Case-insensitive equality comparisons are normally expressed as:
SELECT * SELECT *
FROM tab FROM tab
WHERE LOWER(col) = 'abc'; WHERE lower(col) = 'abc';
This will not use an standard index. However, if you create a This will not use an standard index. However, if you create a
functional index, it will be used: functional index, it will be used:
CREATE INDEX tabindex ON tab (LOWER(col)); CREATE INDEX tabindex ON tab (lower(col));
4.13) In a query, how do I detect if a field is NULL? 4.13) In a query, how do I detect if a field is NULL?

59
doc/src/FAQ/FAQ.html
View File

@ -14,7 +14,7 @@
alink="#0000ff"> alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
<P>Last updated: Sun Oct 13 22:49:56 EDT 2002</P> <P>Last updated: Sun Oct 13 23:15:09 EDT 2002</P>
<P>Current maintainer: Bruce Momjian (<A href= <P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR> "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
@ -78,8 +78,8 @@
<A href="#3.7">3.7</A>) What debugging features are available?<BR> <A href="#3.7">3.7</A>) What debugging features are available?<BR>
<A href="#3.8">3.8</A>) Why do I get <I>"Sorry, too many <A href="#3.8">3.8</A>) Why do I get <I>"Sorry, too many
clients"</I> when trying to connect?<BR> clients"</I> when trying to connect?<BR>
<A href="#3.9">3.9</A>) What are the <I>pg_sorttempNNN.NN</I> <A href="#3.9">3.9</A>) What is in the <I>pgsql_tmp</I>
files in my database directory?<BR> directory?<BR>
<A href="#3.10">3.10</A>) Why do I need to do a dump and restore <A href="#3.10">3.10</A>) Why do I need to do a dump and restore
to upgrade PostgreSQL releases?<BR> to upgrade PostgreSQL releases?<BR>
@ -250,10 +250,11 @@
<P>The database server can run on Windows NT and Win2k using <P>The database server can run on Windows NT and Win2k using
Cygwin, the Cygnus Unix/NT porting library. See Cygwin, the Cygnus Unix/NT porting library. See
<I>pgsql/doc/FAQ_MSWIN</I> in the distribution or the MS Windows FAQ <I>pgsql/doc/FAQ_MSWIN</I> in the distribution or the MS Windows FAQ
at <A href="http://www.PostgreSQL.org/docs/faq-mswin.html">http://www.PostgreSQL.org/docs/faq-mswin.html</A>.</P> at <A href="http://www.PostgreSQL.org/docs/faq-mswin.html">
http://www.PostgreSQL.org/docs/faq-mswin.html</A>.</P>
<p>A native port to some Microsoft platforms is currently being worked <p>A native port to MS Win NT/2000/XP is currently being worked
upon.</p> on.</p>
<H4><A name="1.5">1.5</A>) Where can I get PostgreSQL?</H4> <H4><A name="1.5">1.5</A>) Where can I get PostgreSQL?</H4>
@ -484,7 +485,7 @@
PostgreSQL?</H4> PostgreSQL?</H4>
<P>PostgreSQL has had a first-class infrastructure since we started <P>PostgreSQL has had a first-class infrastructure since we started
in 1994. This is all thanks to Marc Fournier, who has created in 1996. This is all thanks to Marc Fournier, who has created
and managed this infrastructure over the years.</P> and managed this infrastructure over the years.</P>
<P>Quality infrastructure is very important to an open-source <P>Quality infrastructure is very important to an open-source
@ -545,9 +546,9 @@
interface? A report generator? An embedded query language interface? A report generator? An embedded query language
interface?</H4> interface?</H4>
<P>We have a nice graphical user interface called PgAccess, which is <P>We have a nice graphical user interface called PgAccess which can
shipped as part of the distribution. PgAccess also has a report also be used as a report generator. The Web page is
generator. The Web page is <A href="http://www.pgaccess.org/">http://www.pgaccess.org/</A>.</P> <A href="http://www.pgaccess.org/">http://www.pgaccess.org/</A>.</P>
<P>We also include <I>ecpg</I>, which is an embedded SQL query <P>We also include <I>ecpg</I>, which is an embedded SQL query
language interface for C.</P> language interface for C.</P>
@ -565,7 +566,7 @@
<LI>Java (jdbc)</LI> <LI>Java (jdbc)</LI>
<LI>Perl (DBD::Pg)</LI> <LI>Perl (DBD::Pg and perl5)</LI>
<LI>ODBC (odbc)</LI> <LI>ODBC (odbc)</LI>
@ -578,7 +579,9 @@
<LI>PHP ('pg_' functions, Pear::DB)</LI> <LI>PHP ('pg_' functions, Pear::DB)</LI>
</UL> </UL>
<P>Additional interfaces are available at <P>Additional interfaces are available at
<a href="http://www.PostgreSQL.org/interfaces.html">http://www.PostgreSQL.org/interfaces.html</A>. <a href="http://www.PostgreSQL.org/interfaces.html">http://www.PostgreSQL.org/interfaces.html</A>
and
<a href="http://gborg.PostgreSQL.org">http://gborg.PostgreSQL.org</A>.
</P> </P>
<HR> <HR>
@ -765,8 +768,8 @@
the MaxBackendId constant in the MaxBackendId constant in
<I>include/storage/sinvaladt.h</I>.</P> <I>include/storage/sinvaladt.h</I>.</P>
<H4><A name="3.9">3.9</A>) What are the <I>pg_tempNNN.NN</I> <H4><A name="3.9">3.9</A>) What are the <I>pgsql_tmp</I>
files in my database directory?</H4> directory?</H4>
<P>They are temporary files generated by the query executor. For <P>They are temporary files generated by the query executor. For
example, if a sort needs to be done to satisfy an <SMALL>ORDER example, if a sort needs to be done to satisfy an <SMALL>ORDER
@ -774,10 +777,9 @@
<I>-S</I> parameter allows, then temporary files are created to <I>-S</I> parameter allows, then temporary files are created to
hold the extra data.</P> hold the extra data.</P>
<P>The temporary files should be deleted automatically, but might <P>The temporary files are usually deleted automatically, but might
not if a backend crashes during a sort. If you have no backends remain if a backend crashes during a sort. A stop and restart of the
running at the time, it is safe to delete the pg_tempNNN.NN <I>postmaster</I> will remove files from those directories.</P>
files.</P>
<H4><A name="3.10">3.10</A>) Why do I need to do a dump and restore <H4><A name="3.10">3.10</A>) Why do I need to do a dump and restore
to upgrade between major PostgreSQL releases?</H4> to upgrade between major PostgreSQL releases?</H4>
@ -790,10 +792,10 @@
data in a generic format that can then be loaded in using the new internal data in a generic format that can then be loaded in using the new internal
format.</P> format.</P>
<p>In releases where the on-disk format does not change, the <P>In releases where the on-disk format does not change, the
<i>pg_upgrade</i> script can be used to upgrade without a dump/restore. <I>pg_upgrade</I> script can be used to upgrade without a dump/restore.
The release notes mention whether <i>pg_upgrade</i> is available for the The release notes mention whether <I>pg_upgrade</I> is available for the
release.</p> release.</P>
<HR> <HR>
@ -831,8 +833,9 @@
<H4><A name="4.4">4.4</A>) How do you remove a column from a <H4><A name="4.4">4.4</A>) How do you remove a column from a
table?</H4> table?</H4>
<P>Prior to version 7.3, <SMALL>ALTER TABLE DROP COLUMN</SMALL> is not supported. <P>This functionality was added in release 7.3 with
You can do this instead:</P> <SMALL>ALTER TABLE DROP COLUMN</SMALL>. In earlier versions,
you can do this:</P>
<PRE> <PRE>
BEGIN; BEGIN;
LOCK TABLE old_table; LOCK TABLE old_table;
@ -1023,13 +1026,13 @@
<PRE> <PRE>
SELECT * SELECT *
FROM tab FROM tab
WHERE LOWER(col) = 'abc'; WHERE lower(col) = 'abc';
</PRE> </PRE>
This will not use an standard index. However, if you create a This will not use an standard index. However, if you create a
functional index, it will be used: functional index, it will be used:
<PRE> <PRE>
CREATE INDEX tabindex ON tab (LOWER(col)); CREATE INDEX tabindex ON tab (lower(col));
</PRE> </PRE>
<H4><A name="4.13">4.13</A>) In a query, how do I detect if a field <H4><A name="4.13">4.13</A>) In a query, how do I detect if a field
@ -1118,7 +1121,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
and your <SMALL>SERIAL</SMALL> column, respectively. and your <SMALL>SERIAL</SMALL> column, respectively.
<P>Alternatively, you could retrieve the assigned <P>Alternatively, you could retrieve the assigned
<SMALL>SERIAL</SMALL> value with the <I>currval</I>() function <SMALL>SERIAL</SMALL> value with the <I>currval()</I> function
<I>after</I> it was inserted by default, e.g.,</P> <I>after</I> it was inserted by default, e.g.,</P>
<PRE> <PRE>
execute("INSERT INTO person (name) VALUES ('Blaise Pascal')"); execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
@ -1135,7 +1138,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
<H4><A name="4.15.3">4.15.3</A>) Don't <I>currval()</I> and <H4><A name="4.15.3">4.15.3</A>) Don't <I>currval()</I> and
<I>nextval()</I> lead to a race condition with other users?</H4> <I>nextval()</I> lead to a race condition with other users?</H4>
<P>No. <i>currval</i>() returns the current value assigned by your <P>No. <I>currval()</I> returns the current value assigned by your
backend, not by all users.</P> backend, not by all users.</P>
<H4><A name="4.15.4">4.15.4</A>) Why aren't my sequence numbers <H4><A name="4.15.4">4.15.4</A>) Why aren't my sequence numbers