On Fri, Nov 01, 2019 at 11:58:43AM -0500, Justin Pryzby wrote: > Attaching a partition acquires a <literal>SHARE UPDATE EXCLUSIVE</literal> > lock > on the parent table, in addition to <literal>ACCESS EXCLUSIVE</literal> locks > on the table to be attached and the <literal>DEFAULT</literal> partition (if > any). >
Sounds fine. So gathering everything I get the attached. Any thoughts from others? -- Michael
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index d7158c1b03..8e5592c106 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -3952,14 +3952,14 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
<para>
Before running the <command>ATTACH PARTITION</command> command, it is
recommended to create a <literal>CHECK</literal> constraint on the table to
- be attached describing the desired partition constraint. That way,
+ be attached matching the desired partition constraint. That way,
the system will be able to skip the scan to validate the implicit
- partition constraint. Without such a constraint, the table will be
+ partition constraint. Without the <literal>CHECK</literal> constraint, the table will be
scanned to validate the partition constraint while holding an
<literal>ACCESS EXCLUSIVE</literal> lock on that partition
and a <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the parent table.
- One may then drop the constraint after <command>ATTACH PARTITION</command>
- is finished, because it is no longer necessary.
+ It may be desired to drop the redundant <literal>CHECK</literal> constraint
+ after <command>ATTACH PARTITION</command> is finished.
</para>
<para>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 62542cd8a1..d3a37b4a6a 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -841,7 +841,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
or as a default partition by using <literal>DEFAULT</literal>.
For each index in the target table, a corresponding
one will be created in the attached table; or, if an equivalent
- index already exists, will be attached to the target table's index,
+ index already exists, it will be attached to the target table's index,
as if <command>ALTER INDEX ATTACH PARTITION</command> had been executed.
Note that if the existing table is a foreign table, it is currently not
allowed to attach the table as a partition of the target table if there
@@ -864,17 +864,17 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
already exist.
If any of the <literal>CHECK</literal> constraints of the table being
attached is marked <literal>NO INHERIT</literal>, the command will fail;
- such a constraint must be recreated without the <literal>NO INHERIT</literal>
+ such constraints must be recreated without the <literal>NO INHERIT</literal>
clause.
</para>
<para>
If the new partition is a regular table, a full table scan is performed
- to check that no existing row in the table violates the partition
+ to check that existing rows in the table do not violate the partition
constraint. It is possible to avoid this scan by adding a valid
- <literal>CHECK</literal> constraint to the table that would allow only
- the rows satisfying the desired partition constraint before running this
- command. It will be determined using such a constraint that the table
+ <literal>CHECK</literal> constraint to the table that allows only
+ rows satisfying the desired partition constraint before running this
+ command. The <literal>CHECK</literal> constraint will be used to determine that the table
need not be scanned to validate the partition constraint. This does not
work, however, if any of the partition keys is an expression and the
partition does not accept <literal>NULL</literal> values. If attaching
@@ -900,6 +900,14 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
the scan of the new partition, it is always skipped when the default
partition is a foreign table.
</para>
+
+ <para>
+ Attaching a partition acquires a
+ <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the parent table,
+ in addition to <literal>ACCESS EXCLUSIVE</literal> locks on the table
+ to be attached and the default partition (if any).
+ </para>
+
</listitem>
</varlistentry>
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