1010alink ="#0000ff ">
1111< H1 > Frequently Asked Questions (FAQ) for PostgreSQL</ H1 >
1212
13- < P > Last updated: ThuDec 5 00:47:26 EST2002 </ P >
13+ < P > Last updated: ThuFeb 13 23:07:35 EST2003 </ P >
1414
1515< P > Current maintainer: Bruce Momjian (< A href =
1616 "mailto:pgman@candle.pha.pa.us "> pgman@candle.pha.pa.us</ A > )< BR >
@@ -318,7 +318,7 @@ <H4><A name="1.6">1.6</A>) Where can I get support?</H4>
318318
319319< H4 > < A name ="1.7 "> 1.7</ A > ) What is the latest release?</ H4 >
320320
321- < P > The latest release of PostgreSQL is version 7.2.3 .</ P >
321+ < P > The latest release of PostgreSQL is version 7.3.1 .</ P >
322322
323323< P > We plan to have major releases every four months.</ P >
324324
@@ -536,8 +536,8 @@ <H4><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
536536 interface?</ H4 >
537537
538538 Yes, there are several graphical interfaces to PostgreSQL available.
539- These include PgAccess< a href ="http://www.pgaccess.com ">
540- http://www.pgaccess.com </ a > ), PgAdmin II (< a
539+ These include PgAccess< a href ="http://www.pgaccess.org ">
540+ http://www.pgaccess.org </ a > ), PgAdmin II (< a
541541href ="http://www.pgadmin.org "> http://www.pgadmin.org</ a > ,
542542 Win32-only), RHDB Admin (< a
543543href ="http://sources.redhat.com/rhdb/ "> http://sources.redhat.com/rhdb/
@@ -547,10 +547,6 @@ <H4><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
547547 http://phppgadmin.sourceforge.net/</ a > ), a web-based interface to
548548 PostgreSQL.
549549
550- < P > We have a nice graphical user interface called PgAccess which can
551- also be used as a report generator. The Web page is
552- < A href ="http://www.pgaccess.org/ "> http://www.pgaccess.org/</ A > .</ P >
553-
554550< H4 > < A name ="2.4 "> 2.4</ A > ) What languages are able to communicate with
555551 PostgreSQL?</ H4 >
556552
@@ -757,11 +753,6 @@ <H4><A name="3.8">3.8</A>) Why do I get <I>"Sorry, too many
757753 the number of allowed backend processes is so your system won't run
758754 out of resources.</ P >
759755
760- < P > In PostgreSQL versions prior to 6.5, the maximum number of
761- backends was 64, and changing it required a rebuild after altering
762- the MaxBackendId constant in
763- < I > include/storage/sinvaladt.h</ I > .</ P >
764-
765756< H4 > < A name ="3.9 "> 3.9</ A > ) What is in the< I > pgsql_tmp</ I > directory?</ H4 >
766757
767758< P > This directory contains temporary files generated by the query
@@ -947,6 +938,10 @@ <H4><A name="4.8">4.8</A>) My queries are slow or don't make use of
947938 LIMIT 1;
948939</ PRE >
949940
941+ < P > If you believe the optimizer is incorrect in choosing a
942+ sequential scan, use< CODE > SET enable_seqscan TO 'off'</ CODE > and
943+ run tests to see if an index scan is indeed faster.</ P >
944+
950945< P > When using wild-card operators such as< SMALL > LIKE</ SMALL > or
951946< I > ~</ I > , indexes can only be used in certain circumstances:</ P >
952947< UL >
@@ -1039,10 +1034,10 @@ <H4><A name="4.14">4.14</A>) What is the difference between the
10391034< PRE >
10401035Type Internal Name Notes
10411036--------------------------------------------------
1042- "char" char 1 character
1043- CHAR(n) bpchar blank padded to the specified fixed length
10441037VARCHAR(n) varchar size specifies maximum length, no padding
1038+ CHAR(n) bpchar blank padded to the specified fixed length
10451039TEXT text no specific upper limit on length
1040+ "char" char one character
10461041BYTEA bytea variable-length byte array (null-byte safe)
10471042</ PRE >
10481043
@@ -1056,11 +1051,13 @@ <H4><A name="4.14">4.14</A>) What is the difference between the
10561051 stored out-of-line by< SMALL > TOAST</ SMALL > , so the space on disk
10571052 might also be less than expected.</ P >
10581053
1059- < P > < SMALL > CHAR(n)</ SMALL > is best when storing strings that are
1060- usually the same length.< SMALL > VARCHAR(n)</ SMALL > is best when
1061- storing variable-length strings but it limits how long a string can
1062- be.< SMALL > TEXT</ SMALL > is for strings of unlimited length, maximum
1063- 1 gigabyte.< SMALL > BYTEA</ SMALL > is for storing binary data,
1054+ < SMALL > VARCHAR(n)</ SMALL > is best when storing variable-length
1055+ strings and it limits how long a string can be.< SMALL > TEXT</ SMALL >
1056+ is for strings of unlimited length, with a maximum of one gigabyte.
1057+ < P > < SMALL > CHAR(n)</ SMALL > is for storing strings that are all the
1058+ same length.< SMALL > CHAR(n)</ SMALL > pads with blanks to the specified
1059+ length, while< SMALL > VARCHAR(n)</ SMALL > only stores the characters
1060+ supplied.< SMALL > BYTEA</ SMALL > is for storing binary data,
10641061 particularly values that include< SMALL > NULL</ SMALL > bytes. These
10651062 types have similar performance characteristics.</ P >
10661063
@@ -1286,7 +1283,7 @@ <H4><A name="4.22">4.22</A>) Why are my subqueries using
12861283</ PRE >
12871284
12881285 For this to be fast,< CODE > subcol</ CODE > should be an indexed column.
1289- We hope to fix this limitation ina future release .
1286+ This preformance problem will be fixed in7.4 .
12901287
12911288< H4 > < A name ="4.23 "> 4.23</ A > ) How do I perform an outer join?</ H4 >
12921289