+NAME="1.1">1.1) What is PostgreSQL?
PostgreSQL is an enhancement of the POSTGRES database management system, a next-generation DBMS research prototype. While PostgreSQL retains the @@ -183,7 +183,7 @@ name was changed at the end of 1996 to PostgreSQL.
It is pronounced Post-Gres-Q-L. -
PostgreSQL is subject to the following COPYRIGHT.
@@ -215,7 +215,7 @@ MODIFICATIONS.
-
The authors have compiled and tested PostgreSQL on the following @@ -243,7 +243,7 @@ platforms (some of these compiles require gcc):
-
+
It is possible to compile the libpq C library, psql, and other interfaces and binaries to run on MS Windows platforms. In this case, @@ -263,14 +263,14 @@ There is another port using U/Win at http://surya.wipro.com/uwin/ported.html. -
+
The primary anonymous ftp site for PostgreSQL is ftp://ftp.postgreSQL.org/pub
For mirror sites, see our main web site. -
+
There is no official support for PostgreSQL from the University of California, Berkeley. It is maintained through volunteer effort.
@@ -336,14 +336,14 @@ Commercial support for PostgreSQL is available at http://www.pgsql.com/
-
+
The latest release of PostgreSQL is version 7.0.
We plan to have major releases every four months.
-
+
Several manuals, manual pages, and some small test examples are included in the distribution. See the /doc directory. You can also @@ -358,14 +358,14 @@ operators, functions, aggregates, etc.
The web site contains even more documentation.
-
PostgreSQL supports an extended subset of SQL-92. See our TODO for a list of known bugs, missing features, and future plans.
-
+
There is a nice tutorial at
@@ -382,12 +382,12 @@ Addison Wesley. Others like Lan Times Guide to SQL, Groff et al.,
Osborne McGraw-Hill.
-
+
Yes, we easily handle dates past the year 2000AD, and before 2000BC.
-
+
First, download the latest sources and read the PostgreSQL Developers
documentation on our web site, or in the distribution.
@@ -400,7 +400,7 @@ high-quality patches that it was a pain for the existing
committers to keep up, and we had confidence that patches they
committed were likely to be of high quality.
-
+
Fill out the "bug-template" file and send it to: bugs@postgreSQL.org
@@ -410,7 +410,7 @@ HREF="ftp://ftp.postgreSQL.org/pub">ftp://ftp.postgreSQL.org/pub1.11) Is PostgreSQL Y2K compliant?
1.11) Is PostgreSQL Y2K compliant?
1.12) How do I join the development team?
1.12) How do I join the development team?
1.13) How do I submit a bug report?
1.13) How do I submit a bug report?
-
There are several ways of measuring software: features, performance,
@@ -484,6 +484,19 @@ add our code to your product with no limitations, except those outlined
in our BSD-style license stated above.
+
+ +These are the limits: + +
+Maximum size for a database? unlimited (60GB databases exist) +Maximum size for a table? unlimited on all operating systems +Maximum size for a row? 8k, configurable to 32k +Maximum number of rows in a table? unlimited +Maximum number of columns table? unlimited +Maximun number of indexes on a table? unlimited ++The row length limit will be removed in 7.1.
+
There are two ODBC drivers available, PostODBC and OpenLink ODBC.
@@ -512,7 +525,7 @@ HREF="mailto:postgres95@openlink.co.uk">postgres95@openlink.co.uk.
-
A nice introduction to Database-backed Web pages can be seen at: A WWW gateway based on WDB using perl can be downloaded from http://www.eol.ists.ca/~dunlop/wdb-p95 -
We have a nice graphical user interface called pgaccess, which is
@@ -541,7 +554,7 @@ generator. The web page is ecpg, which is an embedded SQL query language interface for
C.
-
We have:
@@ -563,7 +576,7 @@ We have:
-
+
-
The simplest way is to specify the --prefix option when running configure.
@@ -582,7 +595,7 @@ If you forgot to do that, you can edit Makefile.global and change POSTGRESDIR
accordingly, or create a Makefile.custom and define POSTGRESDIR there.
-
It could be a variety of problems, but first check to see that you
@@ -590,7 +603,7 @@ have system V extensions installed in your kernel. PostgreSQL requires
kernel support for shared memory and semaphores.
-
You either do not have shared memory configured properly in kernel or
@@ -600,7 +613,7 @@ and backend processes you configure postmaster to run with.
For most systems, with default numbers of buffers and processes, you
need a minimum of ~1MB.
-
If the error message is IpcSemaphoreCreate: semget failed (No space
@@ -615,7 +628,7 @@ If the error message is something else, you might not have semaphore
support configured in your kernel at all.
-
By default, PostgreSQL only allows connections from the local machine
@@ -625,7 +638,7 @@ unless you add the -i flag to the postmaster,
$PGDATA/pg_hba.conf accordingly. This will allow TCP/IP connections.
-
The default configuration allows only unix domain socket connections
@@ -635,7 +648,7 @@ appropriate host entry to the file
pgsql/data/pg_hba.conf. See the pg_hba.conf manual page.
-
You should not create database users with user id 0 (root). They will be
@@ -644,14 +657,14 @@ of the ability of any user to dynamically link object modules into the
database engine.
-
This problem can be caused by a kernel that is not configured to support
semaphores.
-
Certainly, indices can speed up queries. The EXPLAIN command
@@ -685,7 +698,7 @@ You can also use the CLUSTER command to group data in base tables
match an index. See the cluster(l) manual page for more details.
-
PostgreSQL has several features that report status information that can
@@ -763,7 +776,7 @@ In Postgres versions prior to 6.5, the maximum number of backends was
64, and changing it required a rebuild after altering the MaxBackendId
constant in include/storage/sinvaladt.h.
-
They are temporary files generated by the query executor. For
@@ -775,38 +788,12 @@ The temp files should go away automatically, but might not if a backend
crashes during a sort. If you have no transactions running at the time,
it is safe to delete the pg_tempNNN.NN files.
-
-
-Currently, there is no easy interface to set up user groups. You have to
-explicitly insert/update the pg_group table. For example:
-
-
-
- The fields in pg_group are:
-
-
-
-
Check your locale configuration. PostgreSQL uses the locale settings of
@@ -815,12 +802,12 @@ SET commands to control the date format. Set those accordingly for
your operating environment.
-
See the DECLARE manual page for a description.
-
See the FETCH manual page, or use SELECT ... LIMIT....
@@ -842,7 +829,7 @@ with the -E option so that it will print out the queries it uses
to execute the commands you give.
-
We do not support ALTER TABLE DROP COLUMN, but do
@@ -858,7 +845,7 @@ this:
-
Rows are limited to 8K bytes, but this can be changed by editing
@@ -904,7 +891,7 @@ this data can be estimated at 14MB:
Indexes do not contain as much overhead, but do contain the data that is
being indexed, so they can be large also.
-
psql has a variety of backslash commands to show such information. Use
@@ -915,7 +902,7 @@ illustrates many of the SELECTs needed to get information from
the database system tables.
-
PostgreSQL does not automatically maintain statistics. One has to make
@@ -943,12 +930,12 @@ the string. So, to use indices, LIKE searches should not
begin with %, and ~(regular expression searches) should
start with ^.
-
See the EXPLAIN manual page.
-
+
An r-tree index is used for indexing spatial data. A hash index can't
handle range searches. A B-tree index only handles range searches in a
@@ -971,7 +958,7 @@ extending R-trees require a bit of work and we don't currently have any
documentation on how to do it.
-
The GEQO module in PostgreSQL is intended to solve the query
@@ -983,7 +970,7 @@ For further information see the documentation.
-
The ~ operator does regular-expression matching, and ~*
@@ -994,13 +981,13 @@ effect of case-insensitive LIKE with this:
WHERE lower(textfield) LIKE lower(pattern)
-
You test the column with IS NULL and IS NOT NULL.
-
-
PostgreSQL supports SERIAL data type. It auto-creates a
@@ -1054,7 +1041,7 @@ option or COPY WITH OIDS option to preserve the oids.
For more details, see Bruce Momjian's chapter on
Numbering Rows.
-
+
Probably the simplest approach is to to retrieve the next SERIAL value from the sequence object with the nextval() function before inserting and then insert it explicitly. Using the example table in 4.16.1, that might look like this:
+
No. That has been handled by the backends.
-
+
Oids are PostgreSQL's answer to unique row ids. Every row that is
created in PostgreSQL gets a unique oid. All oids generated during
@@ -1111,7 +1098,7 @@ values. Tids change after rows are modified or reloaded. They are used
by index entries to point to physical rows.
-
Some of the source code and older documentation use terms that have more
@@ -1206,20 +1193,20 @@ We hope to fix this limitation in a future release.
-
The problem could be a number of things. Try testing your user-defined
function in a stand alone test program first.
-
You are pfree'ing something that was not palloc'ed.
Beware of mixing malloc/free and palloc/pfree.
-
@@ -1227,13 +1214,13 @@ Send your extensions to the pgsql-hackers mailing list, and they will
eventually end up in the contrib/ subdirectory.
-
This requires wizardry so extreme that the authors have never
tried it, though in principle it can be done.
-
The Makefiles do not have the proper dependencies for include files. You
--
cgit v1.2.3
2.4) What languages are available to
+
2.4) What languages are available to
communicate with PostgreSQL?
3.1) Why does initdb fail?
3.1) Why does initdb fail?
WARN:heap_modifytuple: repl is
3.2) How do I install PostgreSQL somewhere
+
3.2) How do I install PostgreSQL somewhere
other than /usr/local/pgsql?
3.3) When I start the postmaster, I get a Bad
+
3.3) When I start the postmaster, I get a Bad
System Call or core dumped message. Why?
3.4) When I try to start the postmaster, I
+
3.4) When I try to start the postmaster, I
get IpcMemoryCreate errors. Why?
3.5) When I try to start the postmaster, I
+
3.5) When I try to start the postmaster, I
get IpcSemaphoreCreate errors. Why?
3.6) How do I prevent other hosts from
+
3.6) How do I prevent other hosts from
accessing my PostgreSQL database?
3.7) Why can't I connect to my database from
+
3.7) Why can't I connect to my database from
another machine?
3.8) Why can't I access the database as the root
+
3.8) Why can't I access the database as the root
user?
3.9) All my servers crash under concurrent
+
3.9) All my servers crash under concurrent
table access. Why?
3.10) How do I tune the database engine for
+
3.10) How do I tune the database engine for
better performance?
3.11) What debugging features are available in
+
3.11) What debugging features are available in
PostgreSQL?
3.13) What are the pg_tempNNN.NN files in my
+
3.13) What are the pg_tempNNN.NN files in my
database directory?
3.14) How do I set up a pg_group?
- jolly=> insert into pg_group (groname, grosysid, grolist)
- jolly=> values ('posthackers', '1234', '{5443, 8261}');
- INSERT 548224
- jolly=> grant insert on foo to group posthackers;
- CHANGE
- jolly=>
-
-
4.1) The system seems to be confused about
+
4.1) The system seems to be confused about
commas, decimal points, and date formats.
4.2) What is the exact difference between
+
4.2) What is the exact difference between
binary cursors and normal cursors?
4.3) How do I SELECT only the first few
+
4.3) How do I SELECT only the first few
rows of a query?
4.5) How do you remove a column from a
+
4.5) How do you remove a column from a
table?
4.6) What is the maximum size for a
+
4.6) What is the maximum size for a
row, table, database?
4.8) How do I find out what indices or
+
4.8) How do I find out what indices or
operations are defined in the database?
4.9) My queries are slow or don't make
+
4.9) My queries are slow or don't make
use of the indexes. Why?
4.10) How do I see how the query optimizer is
+
4.10) How do I see how the query optimizer is
evaluating my query?
4.11) What is an R-tree index?
4.11) What is an R-tree index?
4.12) What is Genetic Query
+
4.12) What is Genetic Query
Optimization?
4.13) How do I do regular expression searches and
+
4.13) How do I do regular expression searches and
case-insensitive regexp searching?
4.14) In a query, how do I detect if a field
+
4.14) In a query, how do I detect if a field
is NULL?
4.15) What is the difference between the
+
4.15) What is the difference between the
various character types?
@@ -1025,7 +1012,7 @@ them. Specifically, the penalty is for access to all columns after the
first column of this type.
4.16.1) How do I create a
+
4.16.1) How do I create a
serial/auto-incrementing field?
4.16.2) How do I get the back the generated SERIAL value after an insert?
4.16.2) How do I get the back the generated SERIAL value after an insert?
$newSerialID = nextval('person_id_seq');
@@ -1069,12 +1056,12 @@ Similarly, you could retrieve the just-assigned SERIAL value with the currval
Finally, you could use the oid returned from the INSERT statement to lookup the default value, though this is probably the least portable approach. In perl, using DBI with Edmund Mergl's DBD::Pg module, the oid value is made available via $sth->{pg_oid_status} after $sth->execute().
-4.16.3) Wouldn't use of currval() and nextval() lead to a race condition with other concurrent backend processes?
4.16.3) Wouldn't use of currval() and nextval() lead to a race condition with other concurrent backend processes?
4.17) What is an oid? What is a tid?
4.17) What is an oid? What is a tid?
4.18) What is the meaning of some of the terms
+
4.18) What is the meaning of some of the terms
used in PostgreSQL?
5.1) I wrote a user-defined function. When
+
5.1) I wrote a user-defined function. When
I run it in psql, why does it dump core?
5.2) What does the message:
+
5.2) What does the message:
NOTICE:PortalHeapMemoryFree: 0x402251d0 not in alloc set! mean?
5.3) How can I contribute some nifty new types and
+
5.3) How can I contribute some nifty new types and
functions for PostgreSQL?
5.4) How do I write a C function to return a
+
5.4) How do I write a C function to return a
tuple?
5.5) I have changed a source file. Why does the
+
5.5) I have changed a source file. Why does the
recompile does not see the change?