diff --git a/doc/FAQ b/doc/FAQ index 9cb429dd40c993325da0d3a2e35ca4d8152e71d6..aa4a1f1ea6c56f3da506dd2811bdef1670f7ca3c 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -1,7 +1,7 @@ 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 diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index af0cb7b8b4fc51f79004803da7b7e94ff776da55..8b7add79e768a77e79a4bafc6d92d22e738cde5d 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -14,7 +14,7 @@ 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>