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Remove WITH OIDS support, change oid catalog column visibility.
Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
This commit is contained in:
Andres Freund
@@ -29,7 +29,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
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] )
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[ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]
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[ PARTITION BY { RANGE | LIST | HASH } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITHOUT OIDS ]
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[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
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[ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
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@@ -40,7 +40,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
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[, ... ]
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) ]
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[ PARTITION BY { RANGE | LIST | HASH } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITHOUT OIDS ]
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[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
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[ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
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@@ -51,7 +51,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
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[, ... ]
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) ] { FOR VALUES <replaceable class="parameter">partition_bound_spec</replaceable> | DEFAULT }
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[ PARTITION BY { RANGE | LIST | HASH } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
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[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) | WITHOUT OIDS ]
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[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
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[ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
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@@ -531,17 +531,13 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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<para>
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A partition must have the same column names and types as the partitioned
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table to which it belongs. If the parent is specified <literal>WITH
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OIDS</literal> then all partitions must have OIDs; the parent's OID
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column will be inherited by all partitions just like any other column.
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Modifications to the column names or types of a partitioned table, or
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the addition or removal of an OID column, will automatically propagate
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to all partitions. <literal>CHECK</literal> constraints will be inherited
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automatically by every partition, but an individual partition may specify
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additional <literal>CHECK</literal> constraints; additional constraints with
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the same name and condition as in the parent will be merged with the
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parent constraint. Defaults may be specified separately for each
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partition.
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table to which it belongs. Modifications to the column names or types of
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a partitioned table will automatically propagate to all partitions.
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<literal>CHECK</literal> constraints will be inherited automatically by
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every partition, but an individual partition may specify additional
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<literal>CHECK</literal> constraints; additional constraints with the
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same name and condition as in the parent will be merged with the parent
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constraint. Defaults may be specified separately for each partition.
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</para>
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<para>
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@@ -1145,46 +1141,21 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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This clause specifies optional storage parameters for a table or index;
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see <xref linkend="sql-createtable-storage-parameters"
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endterm="sql-createtable-storage-parameters-title"/> for more
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information. The <literal>WITH</literal> clause for a
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table can also include <literal>OIDS=TRUE</literal> (or just <literal>OIDS</literal>)
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to specify that rows of the new table
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should have OIDs (object identifiers) assigned to them, or
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<literal>OIDS=FALSE</literal> to specify that the rows should not have OIDs.
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If <literal>OIDS</literal> is not specified, the default setting depends upon
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the <xref linkend="guc-default-with-oids"/> configuration parameter.
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(If the new table inherits from any tables that have OIDs, then
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<literal>OIDS=TRUE</literal> is forced even if the command says
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<literal>OIDS=FALSE</literal>.)
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</para>
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<para>
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If <literal>OIDS=FALSE</literal> is specified or implied, the new
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table does not store OIDs and no OID will be assigned for a row inserted
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into it. This is generally considered worthwhile, since it
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will reduce OID consumption and thereby postpone the wraparound
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of the 32-bit OID counter. Once the counter wraps around, OIDs
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can no longer be assumed to be unique, which makes them
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considerably less useful. In addition, excluding OIDs from a
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table reduces the space required to store the table on disk by
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4 bytes per row (on most machines), slightly improving performance.
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</para>
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<para>
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To remove OIDs from a table after it has been created, use <xref
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linkend="sql-altertable"/>.
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information. For backward-compatibility the <literal>WITH</literal>
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clause for a table can also include <literal>OIDS=FALSE</literal> to
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specify that rows of the new table should not contain OIDs (object
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identifiers), <literal>OIDS=TRUE</literal> is not supported anymore.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>WITH OIDS</literal></term>
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<term><literal>WITHOUT OIDS</literal></term>
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<listitem>
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<para>
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These are obsolescent syntaxes equivalent to <literal>WITH (OIDS)</literal>
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and <literal>WITH (OIDS=FALSE)</literal>, respectively. If you wish to give
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both an <literal>OIDS</literal> setting and storage parameters, you must use
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the <literal>WITH ( ... )</literal> syntax; see above.
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This is backward-compatible syntax for declaring a table
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<literal>WITHOUT OIDS</literal>, creating a table <literal>WITH
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OIDS</literal> is not supported anymore.
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</para>
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</listitem>
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</varlistentry>
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@@ -1528,29 +1499,6 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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<refsect1 id="sql-createtable-notes">
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<title>Notes</title>
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<para>
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Using OIDs in new applications is not recommended: where
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possible, using an identity column or other sequence
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generator as the table's primary key is preferred. However, if
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your application does make use of OIDs to identify specific
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rows of a table, it is recommended to create a unique constraint
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on the <structfield>oid</structfield> column of that table, to ensure that
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OIDs in the table will indeed uniquely identify rows even after
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counter wraparound. Avoid assuming that OIDs are unique across
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tables; if you need a database-wide unique identifier, use the
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combination of <structfield>tableoid</structfield> and row OID for the
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purpose.
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</para>
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<tip>
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<para>
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The use of <literal>OIDS=FALSE</literal> is not recommended
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for tables with no primary key, since without either an OID or a
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unique data key, it is difficult to identify specific rows.
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</para>
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</tip>
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<para>
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<productname>PostgreSQL</productname> automatically creates an
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index for each unique constraint and primary key constraint to
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@@ -2089,7 +2037,7 @@ CREATE TABLE cities_partdef
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<para>
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The <literal>WITH</literal> clause is a <productname>PostgreSQL</productname>
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extension; neither storage parameters nor OIDs are in the standard.
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extension; storage parameters are not in the standard.
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</para>
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</refsect2>
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