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Fix INSERT OVERRIDING USER VALUE behavior 

The original implementation disallowed using OVERRIDING USER VALUE on
identity columns defined as GENERATED ALWAYS, which is not per
standard.  So allow that now.

Expand documentation and tests around this.

Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Discussion: https://www.postgresql.org/message-id/flat/CAEZATCVrh2ufCwmzzM%3Dk_OfuLhTTPBJCdFkimst2kry4oHepuQ%40mail.gmail.com
This commit is contained in:
Peter Eisentraut 2020-03-31 08:40:32 +02:00
parent 616ae3d2b0
commit de3bbfcc96
6 changed files with 102 additions and 36 deletions
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30
doc/src/sgml/ref/create_table.sgml
View File

@ -842,15 +842,27 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
<para>
The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
determine how the sequence value is given precedence over a
user-specified value in an <command>INSERT</command> statement.
If <literal>ALWAYS</literal> is specified, a user-specified value is
only accepted if the <command>INSERT</command> statement
specifies <literal>OVERRIDING SYSTEM VALUE</literal>. If <literal>BY
DEFAULT</literal> is specified, then the user-specified value takes
precedence. See <xref linkend="sql-insert"/> for details. (In
the <command>COPY</command> command, user-specified values are always
used regardless of this setting.)
determine how explicitly user-specified values are handled in
<command>INSERT</command> and <command>UPDATE</command> commands.
</para>
<para>
In an <command>INSERT</command> command, if <literal>ALWAYS</literal> is
selected, a user-specified value is only accepted if the
<command>INSERT</command> statement specifies <literal>OVERRIDING SYSTEM
VALUE</literal>. If <literal>BY DEFAULT</literal> is selected, then the
user-specified value takes precedence. See <xref linkend="sql-insert"/>
for details. (In the <command>COPY</command> command, user-specified
values are always used regardless of this setting.)
</para>
<para>
In an <command>UPDATE</command> command, if <literal>ALWAYS</literal> is
selected, any update of the column to any value other than
<literal>DEFAULT</literal> will be rejected. If <literal>BY
DEFAULT</literal> is selected, the column can be updated normally.
(There is no <literal>OVERRIDING</literal> clause for the
<command>UPDATE</command> command.)
</para>
<para>

31
doc/src/sgml/ref/insert.sgml
View File

@ -206,10 +206,19 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
<term><literal>OVERRIDING SYSTEM VALUE</literal></term>
<listitem>
<para>
Without this clause, it is an error to specify an explicit value
(other than <literal>DEFAULT</literal>) for an identity column defined
as <literal>GENERATED ALWAYS</literal>. This clause overrides that
restriction.
If this clause is specified, then any values supplied for identity
columns will override the default sequence-generated values.
</para>
<para>
For an identity column defined as <literal>GENERATED ALWAYS</literal>,
it is an error to insert an explicit value (other than
<literal>DEFAULT</literal>) without specifying either
<literal>OVERRIDING SYSTEM VALUE</literal> or <literal>OVERRIDING USER
VALUE</literal>. (For an identity column defined as
<literal>GENERATED BY DEFAULT</literal>, <literal>OVERRIDING SYSTEM
VALUE</literal> is the normal behavior and specifying it does nothing,
but <productname>PostgreSQL</productname> allows it as an extension.)
</para>
</listitem>
</varlistentry>
@ -219,8 +228,8 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
<listitem>
<para>
If this clause is specified, then any values supplied for identity
columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
and the default sequence-generated values are applied.
columns are ignored and the default sequence-generated values are
applied.
</para>
<para>
@ -238,7 +247,8 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
<term><literal>DEFAULT VALUES</literal></term>
<listitem>
<para>
All columns will be filled with their default values.
All columns will be filled with their default values, as if
<literal>DEFAULT</literal> were explicitly specified for each column.
(An <literal>OVERRIDING</literal> clause is not permitted in this
form.)
</para>
@ -258,8 +268,11 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
<term><literal>DEFAULT</literal></term>
<listitem>
<para>
The corresponding column will be filled with
its default value.
The corresponding column will be filled with its default value. An
identity column will be filled with a new value generated by the
associated sequence. For a generated column, specifying this is
permitted but merely specifies the normal behavior of computing the
column from its generation expression.
</para>
</listitem>
</varlistentry>

7
doc/src/sgml/ref/update.sgml
View File

@ -142,8 +142,11 @@ UPDATE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [
<term><literal>DEFAULT</literal></term>
<listitem>
<para>
Set the column to its default value (which will be NULL if no
specific default expression has been assigned to it).
Set the column to its default value (which will be NULL if no specific
default expression has been assigned to it). An identity column will be
set to a new value generated by the associated sequence. For a
generated column, specifying this is permitted but merely specifies the
normal behavior of computing the column from its generation expression.
</para>
</listitem>
</varlistentry>

4
src/backend/rewrite/rewriteHandler.c
View File

@ -808,7 +808,9 @@ rewriteTargetListIU(List *targetList,
{
if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
{
if (override != OVERRIDING_SYSTEM_VALUE)
if (override == OVERRIDING_USER_VALUE)
apply_default = true;
else if (override != OVERRIDING_SYSTEM_VALUE)
ereport(ERROR,
(errcode(ERRCODE_GENERATED_ALWAYS),
errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),

41
src/test/regress/expected/identity.out
View File

@ -118,53 +118,72 @@ SELECT * FROM itest3;
(5 rows)
-- OVERRIDING tests
-- GENERATED BY DEFAULT
-- This inserts the row as presented:
INSERT INTO itest1 VALUES (10, 'xyz');
INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
-- With GENERATED BY DEFAULT, OVERRIDING SYSTEM VALUE is not allowed
-- by the standard, but we allow it as a no-op, since it is of use if
-- there are multiple identity columns in a table, which is also an
-- extension.
INSERT INTO itest1 OVERRIDING SYSTEM VALUE VALUES (20, 'xyz');
-- This ignores the 30 and uses the sequence value instead:
INSERT INTO itest1 OVERRIDING USER VALUE VALUES (30, 'xyz');
SELECT * FROM itest1;
a | b
----+-----
1 |
2 |
10 | xyz
20 | xyz
3 | xyz
(4 rows)
(5 rows)
-- GENERATED ALWAYS
-- This is an error:
INSERT INTO itest2 VALUES (10, 'xyz');
ERROR: cannot insert into column "a"
DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS.
HINT: Use OVERRIDING SYSTEM VALUE to override.
INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
-- This inserts the row as presented:
INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (20, 'xyz');
-- This ignores the 30 and uses the sequence value instead:
INSERT INTO itest2 OVERRIDING USER VALUE VALUES (30, 'xyz');
SELECT * FROM itest2;
a | b
----+-----
1 |
2 |
10 | xyz
(3 rows)
20 | xyz
3 | xyz
(4 rows)
-- UPDATE tests
-- GENERATED BY DEFAULT is not restricted.
UPDATE itest1 SET a = 101 WHERE a = 1;
UPDATE itest1 SET a = DEFAULT WHERE a = 2;
SELECT * FROM itest1;
a | b
-----+-----
10 | xyz
20 | xyz
3 | xyz
101 |
4 |
(4 rows)
(5 rows)
UPDATE itest2 SET a = 101 WHERE a = 1;
-- GENERATED ALWAYS allows only DEFAULT.
UPDATE itest2 SET a = 101 WHERE a = 1; -- error
ERROR: column "a" can only be updated to DEFAULT
DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS.
UPDATE itest2 SET a = DEFAULT WHERE a = 2;
UPDATE itest2 SET a = DEFAULT WHERE a = 2; -- ok
SELECT * FROM itest2;
a | b
----+-----
1 |
10 | xyz
3 |
(3 rows)
20 | xyz
3 | xyz
4 |
(4 rows)
-- COPY tests
CREATE TABLE itest9 (a int GENERATED ALWAYS AS IDENTITY, b text, c bigint);

25
src/test/regress/sql/identity.sql
View File

@ -64,25 +64,42 @@ SELECT * FROM itest3;
-- OVERRIDING tests
-- GENERATED BY DEFAULT
-- This inserts the row as presented:
INSERT INTO itest1 VALUES (10, 'xyz');
INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
-- With GENERATED BY DEFAULT, OVERRIDING SYSTEM VALUE is not allowed
-- by the standard, but we allow it as a no-op, since it is of use if
-- there are multiple identity columns in a table, which is also an
-- extension.
INSERT INTO itest1 OVERRIDING SYSTEM VALUE VALUES (20, 'xyz');
-- This ignores the 30 and uses the sequence value instead:
INSERT INTO itest1 OVERRIDING USER VALUE VALUES (30, 'xyz');
SELECT * FROM itest1;
-- GENERATED ALWAYS
-- This is an error:
INSERT INTO itest2 VALUES (10, 'xyz');
INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
-- This inserts the row as presented:
INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (20, 'xyz');
-- This ignores the 30 and uses the sequence value instead:
INSERT INTO itest2 OVERRIDING USER VALUE VALUES (30, 'xyz');
SELECT * FROM itest2;
-- UPDATE tests
-- GENERATED BY DEFAULT is not restricted.
UPDATE itest1 SET a = 101 WHERE a = 1;
UPDATE itest1 SET a = DEFAULT WHERE a = 2;
SELECT * FROM itest1;
UPDATE itest2 SET a = 101 WHERE a = 1;
UPDATE itest2 SET a = DEFAULT WHERE a = 2;
-- GENERATED ALWAYS allows only DEFAULT.
UPDATE itest2 SET a = 101 WHERE a = 1; -- error
UPDATE itest2 SET a = DEFAULT WHERE a = 2; -- ok
SELECT * FROM itest2;