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Solve the problem of OID collisions by probing for duplicate OIDs

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whenever we generate a new OID.  This prevents occasional duplicate-OID
errors that can otherwise occur once the OID counter has wrapped around.
Duplicate relfilenode values are also checked for when creating new
physical files.  Per my recent proposal.
This commit is contained in:
Tom Lane
2005-08-12 01:36:05 +00:00
parent 9e4a2de844
commit 721e53785d
20 changed files with 416 additions and 268 deletions
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17
doc/src/sgml/ddl.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.42 2005/07/14 06:17:35 neilc Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.43 2005/08/12 01:35:53 tgl Exp $ -->
<chapter id="ddl">
<title>Data Definition</title>
@ -871,7 +871,7 @@ CREATE TABLE order_items (
The object identifier (object ID) of a row. This column is only
present if the table was created using <literal>WITH
OIDS</literal>, or if the <xref linkend="guc-default-with-oids">
configuration variable was enabled. This column is of type
configuration variable was set. This column is of type
<type>oid</type> (same name as the column); see <xref
linkend="datatype-oid"> for more information about the type.
</para>
@ -992,7 +992,13 @@ CREATE TABLE order_items (
<listitem>
<para>
A unique constraint should be created on the OID column of each
table for which the OID will be used to identify rows.
table for which the OID will be used to identify rows. When such
a unique constraint (or unique index) exists, the system takes
care not to generate an OID matching an already-existing row.
(Of course, this is only possible if the table contains fewer
than 2<superscript>32</> (4 billion) rows, and in practice the
table size had better be much less than that, or performance
may suffer.)
</para>
</listitem>
<listitem>
@ -1005,9 +1011,8 @@ CREATE TABLE order_items (
<listitem>
<para>
The tables in question should be created using <literal>WITH
OIDS</literal> to ensure forward compatibility with future
releases of <productname>PostgreSQL</productname>. It is
planned that <literal>WITHOUT OIDS</> will become the default.
OIDS</literal>. As of <productname>PostgreSQL</productname> 8.1,
<literal>WITHOUT OIDS</> is the default.
</para>
</listitem>
</itemizedlist>