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Update FAQ.

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Bruce Momjian 2002-02-12 17:14:55 +00:00
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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sat Feb 2 16:46:36 EST 2002
Last updated: Tue Feb 12 12:14:52 EST 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@ -80,6 +80,8 @@
4.15.2) How do I get the value of a SERIAL insert?
4.15.3) Don't currval() and nextval() lead to a race condition with
other users?
4.15.4) Why aren't my sequence numbers reused on transaction abort?
Why are there gaps in the numbers of my sequence/SERIAL column?
4.16) What is an OID? What is a TID?
4.17) What is the meaning of some of the terms used in PostgreSQL?
4.18) Why do I get the error "ERROR: Memory exhausted in
@ -863,6 +865,13 @@ BYTEA bytea variable-length byte array (null-byte safe)
No. Currval() returns the current value assigned by your backend, not
by all users.
4.15.4) Why aren't my sequence numbers reused on transaction abort? Why are
there gaps in the numbers of my sequence/SERIAL column?
To improve concurrency, sequence values are given out to running
transactions as needed and are now locked until the transaction
completes. This causes gaps in numbering from aborted transactions.
4.16) What is an OID? What is a TID?
OIDs are PostgreSQL's answer to unique row ids. Every row that is

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doc/src/FAQ/FAQ.html
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alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
<P>Last updated: Sat Feb 2 16:46:36 EST 2002</P>
<P>Last updated: Tue Feb 12 12:14:52 EST 2002</P>
<P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
@ -119,6 +119,9 @@
<SMALL>SERIAL</SMALL> insert?<BR>
<A href="#4.15.3">4.15.3</A>) Don't <I>currval()</I> and
<I>nextval()</I> lead to a race condition with other users?<BR>
<A href="#4.15.4">4.15.4</A>) Why aren't my sequence numbers reused
on transaction abort? Why are there gaps in the numbers of my
sequence/SERIAL column?<BR>
<A href="#4.16">4.16</A>) What is an <SMALL>OID</SMALL>? What is a
<SMALL>TID</SMALL>?<BR>
<A href="#4.17">4.17</A>) What is the meaning of some of the terms
@ -1092,6 +1095,15 @@ BYTEA bytea variable-length byte array (null-byte safe)
<P>No. Currval() returns the current value assigned by your
backend, not by all users.</P>
<H4><A name="4.15.4">4.15.4</A>) Why aren't my sequence numbers reused
on transaction abort? Why are there gaps in the numbers of my
sequence/SERIAL column?</H4>
<P>To improve concurrency, sequence values are given out to running
transactions as needed and are now <i>locked</i> until the
transaction completes. This causes gaps in numbering from aborted
transactions.
<H4><A name="4.16">4.16</A>) What is an <SMALL>OID</SMALL>? What is
a <SMALL>TID</SMALL>?</H4>