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Allow foreign tables to participate in inheritance.

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Foreign tables can now be inheritance children, or parents.  Much of the
system was already ready for this, but we had to fix a few things of
course, mostly in the area of planner and executor handling of row locks.

As side effects of this, allow foreign tables to have NOT VALID CHECK
constraints (and hence to accept ALTER ... VALIDATE CONSTRAINT), and to
accept ALTER SET STORAGE and ALTER SET WITH/WITHOUT OIDS.  Continuing to
disallow these things would've required bizarre and inconsistent special
cases in inheritance behavior.  Since foreign tables don't enforce CHECK
constraints anyway, a NOT VALID one is a complete no-op, but that doesn't
mean we shouldn't allow it.  And it's possible that some FDWs might have
use for SET STORAGE or SET WITH OIDS, though doubtless they will be no-ops
for most.

An additional change in support of this is that when a ModifyTable node
has multiple target tables, they will all now be explicitly identified
in EXPLAIN output, for example:

 Update on pt1  (cost=0.00..321.05 rows=3541 width=46)
   Update on pt1
   Foreign Update on ft1
   Foreign Update on ft2
   Update on child3
   ->  Seq Scan on pt1  (cost=0.00..0.00 rows=1 width=46)
   ->  Foreign Scan on ft1  (cost=100.00..148.03 rows=1170 width=46)
   ->  Foreign Scan on ft2  (cost=100.00..148.03 rows=1170 width=46)
   ->  Seq Scan on child3  (cost=0.00..25.00 rows=1200 width=46)

This was done mainly to provide an unambiguous place to attach "Remote SQL"
fields, but it is useful for inherited updates even when no foreign tables
are involved.

Shigeru Hanada and Etsuro Fujita, reviewed by Ashutosh Bapat and Kyotaro
Horiguchi, some additional hacking by me
This commit is contained in:
Tom Lane
2015-03-22 13:53:11 -04:00
parent 8ac356cde3
commit cb1ca4d800
29 changed files with 1764 additions and 188 deletions
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123
doc/src/sgml/ref/alter_foreign_table.sgml
View File

@@ -21,9 +21,9 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
<replaceable class="PARAMETER">action</replaceable> [, ... ]
ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
ALTER FOREIGN TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
RENAME [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> TO <replaceable class="PARAMETER">new_column_name</replaceable>
ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
@@ -34,20 +34,26 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
ADD [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable class="PARAMETER">collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column_name</replaceable> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">data_type</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable class="PARAMETER">collation</replaceable> ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ])
ADD <replaceable class="PARAMETER">table_constraint</replaceable>
ADD <replaceable class="PARAMETER">table_constraint</replaceable> [ NOT VALID ]
VALIDATE CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable>
DROP CONSTRAINT [ IF EXISTS ] <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
DISABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE REPLICA TRIGGER <replaceable class="PARAMETER">trigger_name</replaceable>
ENABLE ALWAYS TRIGGER <replaceable class="PARAMETER">trigger_name</replaceable>
SET WITH OIDS
SET WITHOUT OIDS
INHERIT <replaceable class="PARAMETER">parent_table</replaceable>
NO INHERIT <replaceable class="PARAMETER">parent_table</replaceable>
OWNER TO { <replaceable class="PARAMETER">new_owner</replaceable> | CURRENT_USER | SESSION_USER }
OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ])
</synopsis>
@@ -94,6 +100,9 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
<listitem>
<para>
This form changes the type of a column of a foreign table.
Again, this has no effect on any underlying storage: this action simply
changes the type that <productname>PostgreSQL</> believes the column to
have.
</para>
</listitem>
</varlistentry>
@@ -145,7 +154,22 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
</varlistentry>
<varlistentry>
<term><literal>ADD <replaceable class="PARAMETER">table_constraint</replaceable></literal></term>
<term>
<literal>SET STORAGE</literal>
</term>
<listitem>
<para>
This form sets the storage mode for a column.
See the similar form of <xref linkend="sql-altertable">
for more details.
Note that the storage mode has no effect unless the table's
foreign-data wrapper chooses to pay attention to it.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ADD <replaceable class="PARAMETER">table_constraint</replaceable></literal> [ NOT VALID ]</term>
<listitem>
<para>
This form adds a new constraint to a foreign table, using the same
@@ -156,10 +180,22 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
<para>
Unlike the case when adding a constraint to a regular table, nothing is
done to verify the constraint is correct; rather, this action simply
declares that some new condition holds for all rows in the foreign
table. (See the discussion in <xref linkend="SQL-CREATEFOREIGNTABLE">.)
Note that constraints on foreign tables cannot be marked
<literal>NOT VALID</> since such constraints are simply declarative.
declares that some new condition should be assumed to hold for all rows
in the foreign table. (See the discussion
in <xref linkend="SQL-CREATEFOREIGNTABLE">.)
If the constraint is marked <literal>NOT VALID</>, then it isn't
assumed to hold, but is only recorded for possible future use.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>VALIDATE CONSTRAINT</literal></term>
<listitem>
<para>
This form marks as valid a constraint that was previously marked
as <literal>NOT VALID</literal>. No action is taken to verify the
constraint, but future queries will assume that it holds.
</para>
</listitem>
</varlistentry>
@@ -187,6 +223,60 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET WITH OIDS</literal></term>
<listitem>
<para>
This form adds an <literal>oid</literal> system column to the
table (see <xref linkend="ddl-system-columns">).
It does nothing if the table already has OIDs.
Unless the table's foreign-data wrapper supports OIDs, this column
will simply read as zeroes.
</para>
<para>
Note that this is not equivalent to <literal>ADD COLUMN oid oid</>;
that would add a normal column that happened to be named
<literal>oid</>, not a system column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET WITHOUT OIDS</literal></term>
<listitem>
<para>
This form removes the <literal>oid</literal> system column from the
table. This is exactly equivalent to
<literal>DROP COLUMN oid RESTRICT</literal>,
except that it will not complain if there is already no
<literal>oid</literal> column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>INHERIT <replaceable class="PARAMETER">parent_table</replaceable></literal></term>
<listitem>
<para>
This form adds the target foreign table as a new child of the specified
parent table.
See the similar form of <xref linkend="sql-altertable">
for more details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>NO INHERIT <replaceable class="PARAMETER">parent_table</replaceable></literal></term>
<listitem>
<para>
This form removes the target foreign table from the list of children of
the specified parent table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>OWNER</literal></term>
<listitem>
@@ -272,7 +362,11 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
<listitem>
<para>
The name (possibly schema-qualified) of an existing foreign table to
alter.
alter. If <literal>ONLY</> is specified before the table name, only
that table is altered. If <literal>ONLY</> is not specified, the table
and all its descendant tables (if any) are altered. Optionally,
<literal>*</> can be specified after the table name to explicitly
indicate that descendant tables are included.
</para>
</listitem>
</varlistentry>
@@ -383,6 +477,15 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">parent_table</replaceable></term>
<listitem>
<para>
A parent table to associate or de-associate with this foreign table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_owner</replaceable></term>
<listitem>