other users?
4.17) What is an OID? What is a TID?
4.18) What is the meaning of some of the terms used in PostgreSQL?
- 4.19) How do I tell what PostgreSQL version I am running?
- 4.20) My large-object operations get invalid large obj descriptor.
+ 4.19) Why do I get the error "ERROR: Memory exhausted in
+ AllocSetAlloc()?"
+ 4.20) How do I tell what PostgreSQL version I am running?
+ 4.21) My large-object operations get invalid large obj descriptor.
Why?
- 4.21) How do I create a column that will default to the current time?
- 4.22) Why are my subqueries using IN so slow?
- 4.23) How do I perform an outer join?
+ 4.22) How do I create a column that will default to the current time?
+ 4.23) Why are my subqueries using IN so slow?
+ 4.24) How do I perform an outer join?
Extending PostgreSQL
5.2) How can I contribute some nifty new types and functions to
PostgreSQL?
5.3) How do I write a C function to return a tuple?
- 5.4) I have changed a source file. Why does the recompile not see the
+ 5.3) I have changed a source file. Why does the recompile not see the
change?
_________________________________________________________________
A list of general database terms can be found at:
http://www.comptechnews.com/~reaster/dbdesign.html
- 4.19) How do I tell what PostgreSQL version I am running?
+ 4.19) Why do I get the error "ERROR: Memory exhausted in AllocSetAlloc()?"
+
+ It is possible you have run out of virtual memory on your system, or
+ your kernel has a low limit for certain resources. Try this before
+ starting the postmaster:
+ ulimit -d 262144
+ limit datasize 256m
+
+ Depending on your shell, only one of these may succeed, but it will
+ set your process data segment limit much higher and perhaps allow the
+ query to complete. This command applies to the current process, and
+ all subprocesses created after the command is run. If you are having a
+ problem with the SQL client because the backend is returning too much
+ data, try it before starting the client.
+
+ 4.20) How do I tell what PostgreSQL version I am running?
From psql, type select version();
- 4.20) My large-object operations get invalid large obj descriptor. Why?
+ 4.21) My large-object operations get invalid large obj descriptor. Why?
You need to put BEGIN WORK and COMMIT around any use of a large object
handle, that is, surrounding lo_open ... lo_close.
If you are using a client interface like ODBC you may need to set
auto-commit off.
- 4.21) How do I create a column that will default to the current time?
+ 4.22) How do I create a column that will default to the current time?
Use now():
CREATE TABLE test (x int, modtime timestamp DEFAULT now() );
- 4.22) Why are my subqueries using IN so slow?
+ 4.23) Why are my subqueries using IN so slow?
Currently, we join subqueries to outer queries by sequentially
scanning the result of the subquery for each row of the outer query. A
We hope to fix this limitation in a future release.
- 4.23) How do I perform an outer join?
+ 4.24) How do I perform an outer join?
PostgreSQL 7.1 and later supports outer joins using the SQL standard
syntax. Here are two examples:
<SMALL>TID</SMALL>?<BR>
<A href="#4.18">4.18</A>) What is the meaning of some of the terms
used in PostgreSQL?<BR>
- <A href="#4.19">4.19</A>) How do I tell what PostgreSQL version I
+ <A href="#4.19">4.19</A>) Why do I get the error <I>"ERROR:
+ Memory exhausted in AllocSetAlloc()?"</I><BR>
+ <A href="#4.20">4.20</A>) How do I tell what PostgreSQL version I
am running? <BR>
- <A href="#4.20">4.20</A>) My large-object operations get
+ <A href="#4.21">4.21</A>) My large-object operations get
<I>invalid large obj descriptor.</I> Why?<BR>
- <A href="#4.21">4.21</A>) How do I create a column that will
+ <A href="#4.22">4.22</A>) How do I create a column that will
default to the current time?<BR>
- <A href="#4.22">4.22</A>) Why are my subqueries using
+ <A href="#4.23">4.23</A>) Why are my subqueries using
<CODE><SMALL>IN</SMALL></CODE> so slow?<BR>
- <A href="#4.23">4.23</A>) How do I perform an outer join?<BR>
+ <A href="#4.24">4.24</A>) How do I perform an outer join?<BR>
<CENTER>
and functions to PostgreSQL?<BR>
<A href="#5.3">5.3</A>) How do I write a C function to return a
tuple?<BR>
- <A href="#5.4">5.4</A>) I have changed a source file. Why does the
+ <A href="#5.4">5.3</A>) I have changed a source file. Why does the
recompile not see the change?<BR>
<HR>
<P>A list of general database terms can be found at: <A href=
"http://www.comptechnews.com/~reaster/dbdesign.html">http://www.comptechnews.com/~reaster/dbdesign.html</A></P>
- <H4><A name="4.19">4.19</A>) How do I tell what PostgreSQL version
+ <H4><A name="4.19">4.19</A>) Why do I get the error <I>"ERROR:
+ Memory exhausted in AllocSetAlloc()?"</I><BR>
+ </H4>
+
+ <P>It is possible you have run out of virtual memory on your
+ system, or your kernel has a low limit for certain resources. Try
+ this before starting the <I>postmaster:</I></P>
+<PRE>
+ ulimit -d 262144
+ limit datasize 256m
+</PRE>
+ Depending on your shell, only one of these may succeed, but it will
+ set your process data segment limit much higher and perhaps allow
+ the query to complete. This command applies to the current process,
+ and all subprocesses created after the command is run. If you are
+ having a problem with the <SMALL>SQL</SMALL> client because the
+ backend is returning too much data, try it before starting the
+ client.
+
+ <H4><A name="4.20">4.20</A>) How do I tell what PostgreSQL version
I am running?<BR>
</H4>
<P>From <I>psql,</I> type <CODE>select version();</CODE></P>
- <H4><A name="4.20">4.20</A>) My large-object operations get
+ <H4><A name="4.21">4.21</A>) My large-object operations get
<I>invalid large obj descriptor.</I> Why?<BR>
</H4>
<P>If you are using a client interface like <SMALL>ODBC</SMALL> you
may need to set <CODE>auto-commit off.</CODE></P>
- <H4><A name="4.21">4.21</A>) How do I create a column that will
+ <H4><A name="4.22">4.22</A>) How do I create a column that will
default to the current time?<BR>
</H4>
</CODE>
</PRE>
- <H4><A name="4.22">4.22</A>) Why are my subqueries using
+ <H4><A name="4.23">4.23</A>) Why are my subqueries using
<CODE><SMALL>IN</SMALL></CODE> so slow?<BR>
</H4>
</PRE>
We hope to fix this limitation in a future release.
- <H4><A name="4.23">4.23</A>) How do I perform an outer join?<BR>
+ <H4><A name="4.24">4.24</A>) How do I perform an outer join?<BR>
</H4>
<P>PostgreSQL 7.1 and later supports outer joins using the SQL
projects / postgresql / commitdiff