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Add control knobs for plpgsql's variable resolution behavior, and make the

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default be "throw error on conflict", as per discussions.  The GUC variable
is plpgsql.variable_conflict, with values "error", "use_variable",
"use_column".  The behavior can also be specified per-function by inserting
one of
	#variable_conflict error
	#variable_conflict use_variable
	#variable_conflict use_column
at the start of the function body.

The 8.5 release notes will need to mention using "use_variable" to retain
backward-compatible behavior, although we should encourage people to migrate
to the much less mistake-prone "error" setting.

Update the plpgsql documentation to match this and other recent changes.
This commit is contained in:
Tom Lane
2009-11-13 22:43:42 +00:00
parent 01038d4ad7
commit 6317609986
9 changed files with 332 additions and 231 deletions
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6
doc/src/sgml/config.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.232 2009/10/21 20:38:58 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.233 2009/11/13 22:43:39 tgl Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@ -5162,8 +5162,8 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
when using custom variables:
<programlisting>
custom_variable_classes = 'plr,plperl'
plr.path = '/usr/lib/R'
custom_variable_classes = 'plpgsql,plperl'
plpgsql.variable_conflict = use_variable
plperl.use_strict = true
plruby.use_strict = true # generates error: unknown class name
</programlisting>

417
doc/src/sgml/plpgsql.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.146 2009/11/10 14:22:45 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.147 2009/11/13 22:43:39 tgl Exp $ -->
<chapter id="plpgsql">
<title><application>PL/pgSQL</application> - <acronym>SQL</acronym> Procedural Language</title>
@ -217,11 +217,11 @@ END <optional> <replaceable>label</replaceable> </optional>;
</para>
<para>
There are two types of comments in <application>PL/pgSQL</>. A double
dash (<literal>--</literal>) starts a comment that extends to the end of
the line. A <literal>/*</literal> starts a block comment that extends to
the next occurrence of <literal>*/</literal>. Block comments nest,
just as in ordinary SQL.
Comments work the same way in <application>PL/pgSQL</> code as in
ordinary SQL. A double dash (<literal>--</literal>) starts a comment
that extends to the end of the line. A <literal>/*</literal> starts a
block comment that extends to the matching occurrence of
<literal>*/</literal>. Block comments nest.
</para>
<para>
@ -327,8 +327,9 @@ arow RECORD;
to the variable when the block is entered. If the <literal>DEFAULT</> clause
is not given then the variable is initialized to the
<acronym>SQL</acronym> null value.
The <literal>CONSTANT</> option prevents the variable from being assigned to,
so that its value remains constant for the duration of the block.
The <literal>CONSTANT</> option prevents the variable from being
assigned to, so that its value will remain constant for the duration of
the block.
If <literal>NOT NULL</>
is specified, an assignment of a null value results in a run-time
error. All variables declared as <literal>NOT NULL</>
@ -727,7 +728,7 @@ SELECT <replaceable>expression</replaceable>
<programlisting>
IF x &lt; y THEN ...
</programlisting>
what happens behind the scenes is
what happens behind the scenes is equivalent to
<programlisting>
PREPARE <replaceable>statement_name</>(integer, integer) AS SELECT $1 &lt; $2;
</programlisting>
@ -761,13 +762,17 @@ PREPARE <replaceable>statement_name</>(integer, integer) AS SELECT $1 &lt; $2;
<para>
An assignment of a value to a <application>PL/pgSQL</application>
variable or row/record field is written as:
variable is written as:
<synopsis>
<replaceable>variable</replaceable> := <replaceable>expression</replaceable>;
</synopsis>
As explained above, the expression in such a statement is evaluated
As explained previously, the expression in such a statement is evaluated
by means of an SQL <command>SELECT</> command sent to the main
database engine. The expression must yield a single value.
database engine. The expression must yield a single value (possibly
a row value, if the variable is a row or record variable). The target
variable can be a simple variable (optionally qualified with a block
name), a field of a row or record variable, or an element of an array
that is a simple variable or field.
</para>
<para>
@ -802,38 +807,12 @@ my_record.user_id := 20;
<para>
Any <application>PL/pgSQL</application> variable name appearing
in the command text is replaced by a parameter symbol, and then the
in the command text is treated as a parameter, and then the
current value of the variable is provided as the parameter value
at run time. This is exactly like the processing described earlier
for expressions; for details see <xref linkend="plpgsql-var-subst">.
As an example, if you write:
<programlisting>
DECLARE
key TEXT;
delta INTEGER;
BEGIN
...
UPDATE mytab SET val = val + delta WHERE id = key;
</programlisting>
the command text seen by the main SQL engine will look like:
<programlisting>
UPDATE mytab SET val = val + $1 WHERE id = $2;
</programlisting>
Although you don't normally have to think about this, it's helpful
to know it when you need to make sense of syntax-error messages.
</para>
<caution>
<para>
<application>PL/pgSQL</application> will substitute for any identifier
matching one of the function's declared variables; it is not bright
enough to know whether that's what you meant! Thus, it is a bad idea
to use a variable name that is the same as any table, column, or
function name that you need to reference in commands within the
function. For more discussion see <xref linkend="plpgsql-var-subst">.
</para>
</caution>
<para>
When executing a SQL command in this way,
<application>PL/pgSQL</application> plans the command just once
@ -940,7 +919,7 @@ DELETE ... RETURNING <replaceable>expressions</replaceable> INTO <optional>STRIC
<para>
If a row or a variable list is used as target, the query's result columns
must exactly match the structure of the target as to number and data
types, or a run-time error
types, or else a run-time error
occurs. When a record variable is the target, it automatically
configures itself to the row type of the query result columns.
</para>
@ -1089,7 +1068,9 @@ EXECUTE 'SELECT count(*) FROM mytable WHERE inserted_by = $1 AND inserted &lt;=
INTO c
USING checked_user, checked_date;
</programlisting>
</para>
<para>
Note that parameter symbols can only be used for data values
&mdash; if you want to use dynamically determined table or column
names, you must insert them into the command string textually.
@ -1102,6 +1083,11 @@ EXECUTE 'SELECT count(*) FROM '
INTO c
USING checked_user, checked_date;
</programlisting>
Another restriction on parameter symbols is that they only work in
<command>SELECT</>, <command>INSERT</>, <command>UPDATE</>, and
<command>DELETE</> commands. In other statement
types (generically called utility statements), you must insert
values textually even if they are just data values.
</para>
<para>
@ -1303,6 +1289,7 @@ GET DIAGNOSTICS integer_var = ROW_COUNT;
type <type>boolean</type>. <literal>FOUND</literal> starts out
false within each <application>PL/pgSQL</application> function call.
It is set by each of the following types of statements:
<itemizedlist>
<listitem>
<para>
@ -1363,11 +1350,17 @@ GET DIAGNOSTICS integer_var = ROW_COUNT;
</listitem>
</itemizedlist>
Other <application>PL/pgSQL</application> statements do not change
the state of <literal>FOUND</literal>.
Note in particular that <command>EXECUTE</command>
changes the output of <command>GET DIAGNOSTICS</command>, but
does not change <literal>FOUND</literal>.
</para>
<para>
<literal>FOUND</literal> is a local variable within each
<application>PL/pgSQL</application> function; any changes to it
affect only the current function. <literal>EXECUTE</literal>
changes the output of <command>GET DIAGNOSTICS</command>, but
does not change the state of <literal>FOUND</literal>.
affect only the current function.
</para>
</sect2>
@ -1450,7 +1443,7 @@ RETURN <replaceable>expression</replaceable>;
<command>RETURN</command> with an expression terminates the
function and returns the value of
<replaceable>expression</replaceable> to the caller. This form
is to be used for <application>PL/pgSQL</> functions that do
is used for <application>PL/pgSQL</> functions that do
not return a set.
</para>
@ -2699,7 +2692,7 @@ DELETE FROM <replaceable>table</replaceable> WHERE CURRENT OF <replaceable>curso
or deleted using the cursor to identify the row. There are
restrictions on what the cursor's query can be (in particular,
no grouping) and it's best to use <literal>FOR UPDATE</> in the
cursor. For additional information see the
cursor. For more information see the
<xref linkend="sql-declare" endterm="sql-declare-title">
reference page.
</para>
@ -3173,9 +3166,10 @@ RAISE unique_violation USING MESSAGE = 'Duplicate user ID: ' || user_id;
<listitem>
<para>
Data type array of <type>text</type>; the arguments from
the <command>CREATE TRIGGER</command> statement.
the <command>CREATE TRIGGER</command> statement.
The index counts from 0. Invalid
indices (less than 0 or greater than or equal to <varname>tg_nargs</>) result in a null value.
indexes (less than 0 or greater than or equal to <varname>tg_nargs</>)
result in a null value.
</para>
</listitem>
</varlistentry>
@ -3485,139 +3479,170 @@ SELECT * FROM sales_summary_bytime;
<title>Variable Substitution</title>
<para>
When <application>PL/pgSQL</> prepares a SQL statement or expression
for execution, any <application>PL/pgSQL</application> variable name
appearing in the statement or expression is replaced by a parameter symbol,
<literal>$<replaceable>n</replaceable></literal>. The current value
of the variable is then provided as the value for the parameter whenever
the statement or expression is executed. As an example, consider the
function
SQL statements and expressions within a <application>PL/pgSQL</> function
can refer to variables and parameters of the function. Behind the scenes,
<application>PL/pgSQL</> substitutes query parameters for such references.
Parameters will only be substituted in places where a parameter or
column reference is syntactically allowed. As an extreme case, consider
this example of poor programming style:
<programlisting>
CREATE FUNCTION logfunc(logtxt text) RETURNS void AS $$
INSERT INTO foo (foo) VALUES (foo);
</programlisting>
The first occurrence of <literal>foo</> must syntactically be a table
name, so it will not be substituted, even if the function has a variable
named <literal>foo</>. The second occurrence must be the name of a
column of the table, so it will not be substituted either. Only the
third occurrence is a candidate to be a reference to the function's
variable.
</para>
<note>
<para>
<productname>PostgreSQL</productname> versions before 8.5 would try
to substitute the variable in all three cases, leading to syntax errors.
</para>
</note>
<para>
Since the names of variables are syntactically no different from the names
of table columns, there can be ambiguity in statements that also refer to
tables: is a given name meant to refer to a table column, or a variable?
Let's change the previous example to
<programlisting>
INSERT INTO dest (col) SELECT foo + bar FROM src;
</programlisting>
Here, <literal>dest</> and <literal>src</> must be table names, and
<literal>col</> must be a column of <literal>dest</>, but <literal>foo</>
and <literal>bar</> might reasonably be either variables of the function
or columns of <literal>src</>.
</para>
<para>
By default, <application>PL/pgSQL</> will report an error if a name
in a SQL statement could refer to either a variable or a table column.
You can fix such a problem by renaming the variable or column,
or by qualifying the ambiguous reference, or by telling
<application>PL/pgSQL</> which interpretation to prefer.
</para>
<para>
The simplest solution is to rename the variable or column.
A common coding rule is to use a
different naming convention for <application>PL/pgSQL</application>
variables than you use for column names. For example,
if you consistently name function variables
<literal>v_<replaceable>something</></literal> while none of your
column names start with <literal>v_</>, no conflicts will occur.
</para>
<para>
Alternatively you can qualify ambiguous references to make them clear.
In the above example, <literal>src.foo</> would be an unambiguous reference
to the table column. To create an unambiguous reference to a variable,
declare it in a labeled block and use the block's label
(see <xref linkend="plpgsql-structure">). For example,
<programlisting>
&lt;&lt;block&gt;&gt;
DECLARE
foo int;
BEGIN
foo := ...;
INSERT INTO dest (col) SELECT block.foo + bar FROM src;
</programlisting>
Here <literal>block.foo</> means the variable even if there is a column
<literal>foo</> in <literal>src</>. Function parameters, as well as
special variables such as <literal>FOUND</>, can be qualified by the
function's name, because they are implicitly declared in an outer block
labeled with the function's name.
</para>
<para>
Sometimes it is impractical to fix all the ambiguous references in a
large body of <application>PL/pgSQL</> code. In such cases you can
specify that <application>PL/pgSQL</> should resolve ambiguous references
as the variable (which is compatible with <application>PL/pgSQL</>'s
behavior before <productname>PostgreSQL</productname> 8.5), or as the
table column (which is compatible with some other systems such as
<productname>Oracle</productname>).
</para>
<indexterm>
<primary><varname>plpgsql.variable_conflict</> configuration parameter</primary>
</indexterm>
<para>
To change this behavior on a system-wide basis, set the configuration
parameter <literal>plpgsql.variable_conflict</> to one of
<literal>error</>, <literal>use_variable</>, or
<literal>use_column</> (where <literal>error</> is the factory default).
This parameter affects subsequent compilations
of statements in <application>PL/pgSQL</> functions, but not statements
already compiled in the current session. To set the parameter before
<application>PL/pgSQL</> has been loaded, it is necessary to have added
<quote><literal>plpgsql</></> to the <xref
linkend="guc-custom-variable-classes"> list in
<filename>postgresql.conf</filename>. Because changing this setting
can cause unexpected changes in the behavior of <application>PL/pgSQL</>
functions, it can only be changed by a superuser.
</para>
<para>
You can also set the behavior on a function-by-function basis, by
inserting one of these special commands at the start of the function
text:
<programlisting>
#variable_conflict error
#variable_conflict use_variable
#variable_conflict use_column
</programlisting>
These commands affect only the function they are written in, and override
the setting of <literal>plpgsql.variable_conflict</>. An example is
<programlisting>
CREATE FUNCTION stamp_user(id int, comment text) RETURNS void AS $$
#variable_conflict use_variable
DECLARE
curtime timestamp := now();
BEGIN
INSERT INTO logtable VALUES (logtxt, curtime);
UPDATE users SET last_modified = curtime, comment = comment
WHERE users.id = id;
END;
$$ LANGUAGE plpgsql;
</programlisting>
The <command>INSERT</> statement will effectively be processed as
<programlisting>
PREPARE <replaceable>statement_name</>(text, timestamp) AS
INSERT INTO logtable VALUES ($1, $2);
</programlisting>
followed on each execution by <command>EXECUTE</> with the current
actual values of the two variables. (Note: here we are speaking of
the main SQL engine's
<xref linkend="sql-execute" endterm="sql-execute-title"> command,
not <application>PL/pgSQL</application>'s <command>EXECUTE</>.)
</para>
<para>
<emphasis>The substitution mechanism will replace any token that matches a
known variable's name.</> This poses various traps for the unwary.
For example, it is a bad idea
to use a variable name that is the same as any table or column name
that you need to reference in queries within the function, because
what you think is a table or column name will still get replaced.
In the above example, suppose that <structname>logtable</> has
column names <structfield>logtxt</> and <structfield>logtime</>,
and we try to write the <command>INSERT</> as
<programlisting>
INSERT INTO logtable (logtxt, logtime) VALUES (logtxt, curtime);
</programlisting>
This will be fed to the main SQL parser as
<programlisting>
INSERT INTO logtable ($1, logtime) VALUES ($1, $2);
</programlisting>
resulting in a syntax error like this:
<screen>
ERROR: syntax error at or near "$1"
LINE 1: INSERT INTO logtable ( $1 , logtime) VALUES ( $1 , $2 )
^
QUERY: INSERT INTO logtable ( $1 , logtime) VALUES ( $1 , $2 )
CONTEXT: SQL statement in PL/PgSQL function "logfunc2" near line 5
</screen>
</para>
<para>
This example is fairly easy to diagnose, since it leads to an
obvious syntax error. Much nastier are cases where the substitution
is syntactically permissible, since the only symptom may be misbehavior
of the function. In one case, a user wrote something like this:
In the <literal>UPDATE</> command, <literal>curtime</>, <literal>comment</>,
and <literal>id</> will refer to the function's variable and parameters
whether or not <literal>users</> has columns of those names. Notice
that we had to qualify the reference to <literal>users.id</> in the
<literal>WHERE</> clause to make it refer to the table column.
But we did not have to qualify the reference to <literal>comment</>
as a target in the <literal>UPDATE</> list, because syntactically
that must be a column of <literal>users</>. We could write the same
function without depending on the <literal>variable_conflict</> setting
in this way:
<programlisting>
CREATE FUNCTION stamp_user(id int, comment text) RETURNS void AS $$
&lt;&lt;fn&gt;&gt;
DECLARE
val text;
search_key integer;
curtime timestamp := now();
BEGIN
...
FOR val IN SELECT val FROM table WHERE key = search_key LOOP ...
UPDATE users SET last_modified = fn.curtime, comment = stamp_user.comment
WHERE users.id = stamp_user.id;
END;
$$ LANGUAGE plpgsql;
</programlisting>
and wondered why all his table entries seemed to be NULL. Of course
what happened here was that the query became
<programlisting>
SELECT $1 FROM table WHERE key = $2
</programlisting>
and thus it was just an expensive way of assigning <literal>val</>'s
current value back to itself for each row.
</para>
<para>
A commonly used coding rule for avoiding such traps is to use a
different naming convention for <application>PL/pgSQL</application>
variables than you use for table and column names. For example,
if all your variables are named
<literal>v_<replaceable>something</></literal> while none of your
table or column names start with <literal>v_</>, you're pretty safe.
</para>
<para>
Another workaround is to use qualified (dotted) names for SQL entities.
For instance we could safely have written the above example as
<programlisting>
FOR val IN SELECT table.val FROM table WHERE key = search_key LOOP ...
</programlisting>
because <application>PL/pgSQL</application> will not substitute a
variable for a trailing component of a qualified name.
However this solution does not work in every case &mdash; you can't
qualify a name in an <command>INSERT</>'s column name list, for instance.
Another point is that record and row variable names will be matched to
the first components of qualified names, so a qualified SQL name is
still vulnerable in some cases.
In such cases choosing a non-conflicting variable name is the only way.
</para>
<para>
Another technique you can use is to attach a label to the block in
which your variables are declared, and then qualify the variable names
in your SQL commands (see <xref linkend="plpgsql-structure">).
For example,
<programlisting>
&lt;&lt;pl&gt;&gt;
DECLARE
val text;
BEGIN
...
UPDATE table SET col = pl.val WHERE ...
</programlisting>
This is not in itself a solution to the problem of conflicts,
since an unqualified name in a SQL command is still at risk of being
interpreted the <quote>wrong</> way. But it is useful for clarifying
the intent of potentially-ambiguous code.
</para>
<para>
Variable substitution does not happen in the command string given
to <command>EXECUTE</> or one of its variants. If you need to
insert a varying value into such a command, do so as part of
constructing the string value, as illustrated in
constructing the string value, or use <literal>USING</>, as illustrated in
<xref linkend="plpgsql-statements-executing-dyn">.
</para>
<para>
Variable substitution currently works only in <command>SELECT</>,
<command>INSERT</>, <command>UPDATE</>, and <command>DELETE</> commands,
because the main SQL engine allows parameter symbols only in these
because the main SQL engine allows query parameters only in these
commands. To use a non-constant name or value in other statement
types (generically called utility statements), you must construct
the utility statement as a string and <command>EXECUTE</> it.
@ -3660,47 +3685,17 @@ CONTEXT: SQL statement in PL/PgSQL function "logfunc2" near line 5
</para>
<para>
Once <application>PL/pgSQL</> has made an execution plan for a particular
command in a function, it will reuse that plan for the life of the
database connection. This is usually a win for performance, but it
can cause some problems if you dynamically
alter your database schema. For example:
<programlisting>
CREATE FUNCTION populate() RETURNS integer AS $$
DECLARE
-- declarations
BEGIN
PERFORM my_function();
END;
$$ LANGUAGE plpgsql;
</programlisting>
If you execute the above function, it will reference the OID for
<function>my_function()</function> in the execution plan produced for
the <command>PERFORM</command> statement. Later, if you
drop and recreate <function>my_function()</function>, then
<function>populate()</function> will not be able to find
<function>my_function()</function> anymore. You would then have to
start a new database session so that <function>populate()</function>
will be compiled afresh, before it will work again. You can avoid
this problem by using <command>CREATE OR REPLACE FUNCTION</command>
when updating the definition of
<function>my_function</function>, since when a function is
<quote>replaced</quote>, its OID is not changed.
A saved plan will be re-planned automatically if there is any schema
change to any table used in the query, or if any user-defined function
used in the query is redefined. This makes the re-use of prepared plans
transparent in most cases, but there are corner cases where a stale plan
might be re-used. An example is that dropping and re-creating a
user-defined operator won't affect already-cached plans; they'll continue
to call the original operator's underlying function, if that has not been
changed. When necessary, the cache can be flushed by starting a fresh
database session.
</para>
<note>
<para>
In <productname>PostgreSQL</productname> 8.3 and later, saved plans
will be replaced whenever any schema changes have occurred to any
tables they reference. This eliminates one of the major disadvantages
of saved plans. However, there is no such mechanism for function
references, and thus the above example involving a reference to a
deleted function is still valid.
</para>
</note>
<para>
Because <application>PL/pgSQL</application> saves execution plans
in this way, SQL commands that appear directly in a
@ -4046,28 +4041,19 @@ a_output := a_output || $$ if v_$$ || referrer_keys.kind || $$ like '$$
<application>PL/pgSQL</application> are:
<itemizedlist>
<listitem>
<para>
There are no default values for parameters in <productname>PostgreSQL</>.
</para>
</listitem>
<listitem>
<para>
You can overload function names in <productname>PostgreSQL</>. This is
often used to work around the lack of default parameters.
</para>
</listitem>
<listitem>
<para>
If a name used in a SQL command could be either a column name of a
table or a reference to a variable of the function,
<application>PL/SQL</> treats it as a column name, while
<application>PL/pgSQL</> treats it as a variable name. It's best
to avoid such ambiguities in the first place, but if necessary you
can fix them by properly qualifying the ambiguous name.
(See <xref linkend="plpgsql-var-subst">.)
<application>PL/SQL</> treats it as a column name. This corresponds
to <application>PL/pgSQL</>'s
<literal>plpgsql.variable_conflict</> = <literal>use_column</>
behavior, which is not the default,
as explained in <xref linkend="plpgsql-var-subst">.
It's often best to avoid such ambiguities in the first place,
but if you have to port a large amount of code that depends on
this behavior, setting <literal>variable_conflict</> may be the
best solution.
</para>
</listitem>
@ -4537,7 +4523,8 @@ $$ LANGUAGE plpgsql;
The exception names supported by <application>PL/pgSQL</> are
different from Oracle's. The set of built-in exception names
is much larger (see <xref linkend="errcodes-appendix">). There
is not currently a way to declare user-defined exception names.
is not currently a way to declare user-defined exception names,
although you can throw user-chosen SQLSTATE values instead.
</para>
</callout>
</calloutlist>

22
src/pl/plpgsql/src/gram.y
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.135 2009/11/12 00:13:00 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.136 2009/11/13 22:43:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -256,6 +256,7 @@ static List *read_raise_options(void);
%token <keyword> K_ELSIF
%token <keyword> K_END
%token <keyword> K_ERRCODE
%token <keyword> K_ERROR
%token <keyword> K_EXCEPTION
%token <keyword> K_EXECUTE
%token <keyword> K_EXIT
@ -301,7 +302,10 @@ static List *read_raise_options(void);
%token <keyword> K_THEN
%token <keyword> K_TO
%token <keyword> K_TYPE
%token <keyword> K_USE_COLUMN
%token <keyword> K_USE_VARIABLE
%token <keyword> K_USING
%token <keyword> K_VARIABLE_CONFLICT
%token <keyword> K_WARNING
%token <keyword> K_WHEN
%token <keyword> K_WHILE
@ -322,6 +326,18 @@ comp_option : '#' K_OPTION K_DUMP
{
plpgsql_DumpExecTree = true;
}
| '#' K_VARIABLE_CONFLICT K_ERROR
{
plpgsql_curr_compile->resolve_option = PLPGSQL_RESOLVE_ERROR;
}
| '#' K_VARIABLE_CONFLICT K_USE_VARIABLE
{
plpgsql_curr_compile->resolve_option = PLPGSQL_RESOLVE_VARIABLE;
}
| '#' K_VARIABLE_CONFLICT K_USE_COLUMN
{
plpgsql_curr_compile->resolve_option = PLPGSQL_RESOLVE_COLUMN;
}
;
opt_semi :
@ -1969,6 +1985,7 @@ unreserved_keyword :
| K_DETAIL
| K_DUMP
| K_ERRCODE
| K_ERROR
| K_FIRST
| K_FORWARD
| K_HINT
@ -1991,6 +2008,9 @@ unreserved_keyword :
| K_SCROLL
| K_SQLSTATE
| K_TYPE
| K_USE_COLUMN
| K_USE_VARIABLE
| K_VARIABLE_CONFLICT
| K_WARNING
;

12
src/pl/plpgsql/src/pl_comp.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.145 2009/11/12 00:13:00 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.146 2009/11/13 22:43:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -351,7 +351,7 @@ do_compile(FunctionCallInfo fcinfo,
function->fn_is_trigger = is_trigger;
function->fn_cxt = func_cxt;
function->out_param_varno = -1; /* set up for no OUT param */
function->resolve_option = PLPGSQL_RESOLVE_BEFORE;
function->resolve_option = plpgsql_variable_conflict;
/*
* Initialize the compiler, particularly the namespace stack. The
@ -782,7 +782,7 @@ plpgsql_compile_inline(char *proc_source)
function->fn_is_trigger = false;
function->fn_cxt = func_cxt;
function->out_param_varno = -1; /* set up for no OUT param */
function->resolve_option = PLPGSQL_RESOLVE_BEFORE;
function->resolve_option = plpgsql_variable_conflict;
plpgsql_ns_init();
plpgsql_ns_push(func_name);
@ -948,7 +948,7 @@ plpgsql_pre_column_ref(ParseState *pstate, ColumnRef *cref)
{
PLpgSQL_expr *expr = (PLpgSQL_expr *) pstate->p_ref_hook_state;
if (expr->func->resolve_option == PLPGSQL_RESOLVE_BEFORE)
if (expr->func->resolve_option == PLPGSQL_RESOLVE_VARIABLE)
return resolve_column_ref(expr, cref);
else
return NULL;
@ -963,10 +963,10 @@ plpgsql_post_column_ref(ParseState *pstate, ColumnRef *cref, Node *var)
PLpgSQL_expr *expr = (PLpgSQL_expr *) pstate->p_ref_hook_state;
Node *myvar;
if (expr->func->resolve_option == PLPGSQL_RESOLVE_BEFORE)
if (expr->func->resolve_option == PLPGSQL_RESOLVE_VARIABLE)
return NULL; /* we already found there's no match */
if (expr->func->resolve_option == PLPGSQL_RESOLVE_AFTER && var != NULL)
if (expr->func->resolve_option == PLPGSQL_RESOLVE_COLUMN && var != NULL)
return NULL; /* there's a table column, prefer that */
myvar = resolve_column_ref(expr, cref);

24
src/pl/plpgsql/src/pl_handler.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_handler.c,v 1.47 2009/11/04 22:26:07 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_handler.c,v 1.48 2009/11/13 22:43:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -26,6 +26,17 @@
PG_MODULE_MAGIC;
/* Custom GUC variable */
static const struct config_enum_entry variable_conflict_options[] = {
{"error", PLPGSQL_RESOLVE_ERROR, false},
{"use_variable", PLPGSQL_RESOLVE_VARIABLE, false},
{"use_column", PLPGSQL_RESOLVE_COLUMN, false},
{NULL, 0, false}
};
int plpgsql_variable_conflict = PLPGSQL_RESOLVE_ERROR;
/* Hook for plugins */
PLpgSQL_plugin **plugin_ptr = NULL;
@ -45,6 +56,17 @@ _PG_init(void)
pg_bindtextdomain(TEXTDOMAIN);
DefineCustomEnumVariable("plpgsql.variable_conflict",
gettext_noop("Sets handling of conflicts between PL/pgSQL variable names and table column names."),
NULL,
&plpgsql_variable_conflict,
PLPGSQL_RESOLVE_ERROR,
variable_conflict_options,
PGC_SUSET, 0,
NULL, NULL);
EmitWarningsOnPlaceholders("plpgsql");
plpgsql_HashTableInit();
RegisterXactCallback(plpgsql_xact_cb, NULL);
RegisterSubXactCallback(plpgsql_subxact_cb, NULL);

6
src/pl/plpgsql/src/pl_scanner.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_scanner.c,v 1.1 2009/11/12 00:13:00 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_scanner.c,v 1.2 2009/11/13 22:43:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -113,6 +113,7 @@ static const ScanKeyword unreserved_keywords[] = {
PG_KEYWORD("detail", K_DETAIL, UNRESERVED_KEYWORD)
PG_KEYWORD("dump", K_DUMP, UNRESERVED_KEYWORD)
PG_KEYWORD("errcode", K_ERRCODE, UNRESERVED_KEYWORD)
PG_KEYWORD("error", K_ERROR, UNRESERVED_KEYWORD)
PG_KEYWORD("first", K_FIRST, UNRESERVED_KEYWORD)
PG_KEYWORD("forward", K_FORWARD, UNRESERVED_KEYWORD)
PG_KEYWORD("hint", K_HINT, UNRESERVED_KEYWORD)
@ -135,6 +136,9 @@ static const ScanKeyword unreserved_keywords[] = {
PG_KEYWORD("scroll", K_SCROLL, UNRESERVED_KEYWORD)
PG_KEYWORD("sqlstate", K_SQLSTATE, UNRESERVED_KEYWORD)
PG_KEYWORD("type", K_TYPE, UNRESERVED_KEYWORD)
PG_KEYWORD("use_column", K_USE_COLUMN, UNRESERVED_KEYWORD)
PG_KEYWORD("use_variable", K_USE_VARIABLE, UNRESERVED_KEYWORD)
PG_KEYWORD("variable_conflict", K_VARIABLE_CONFLICT, UNRESERVED_KEYWORD)
PG_KEYWORD("warning", K_WARNING, UNRESERVED_KEYWORD)
};

10
src/pl/plpgsql/src/plpgsql.h
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.124 2009/11/12 00:13:00 tgl Exp $
* $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.125 2009/11/13 22:43:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -147,9 +147,9 @@ enum
*/
typedef enum
{
PLPGSQL_RESOLVE_BEFORE, /* prefer plpgsql var to table column */
PLPGSQL_RESOLVE_AFTER, /* prefer table column to plpgsql var */
PLPGSQL_RESOLVE_ERROR /* throw error if ambiguous */
PLPGSQL_RESOLVE_ERROR, /* throw error if ambiguous */
PLPGSQL_RESOLVE_VARIABLE, /* prefer plpgsql var to table column */
PLPGSQL_RESOLVE_COLUMN /* prefer table column to plpgsql var */
} PLpgSQL_resolve_option;
@ -794,6 +794,8 @@ typedef struct
* Global variable declarations
**********************************************************************/
extern int plpgsql_variable_conflict;
extern bool plpgsql_check_syntax;
extern bool plpgsql_DumpExecTree;
extern bool plpgsql_LookupIdentifiers;

38
src/test/regress/expected/plpgsql.out
View File

@ -4004,6 +4004,7 @@ select scope_test();
drop function scope_test();
-- Check handling of conflicts between plpgsql vars and table columns.
set plpgsql.variable_conflict = error;
create function conflict_test() returns setof int8_tbl as $$
declare r record;
q1 bigint := 42;
@ -4013,6 +4014,23 @@ begin
end loop;
end;
$$ language plpgsql;
select * from conflict_test();
ERROR: column reference "q1" is ambiguous
LINE 1: select q1,q2 from int8_tbl
^
DETAIL: It could refer to either a PL/pgSQL variable or a table column.
QUERY: select q1,q2 from int8_tbl
CONTEXT: PL/pgSQL function "conflict_test" line 4 at FOR over SELECT rows
create or replace function conflict_test() returns setof int8_tbl as $$
#variable_conflict use_variable
declare r record;
q1 bigint := 42;
begin
for r in select q1,q2 from int8_tbl loop
return next r;
end loop;
end;
$$ language plpgsql;
select * from conflict_test();
q1 | q2
----+-------------------
@ -4023,6 +4041,26 @@ select * from conflict_test();
42 | -4567890123456789
(5 rows)
create or replace function conflict_test() returns setof int8_tbl as $$
#variable_conflict use_column
declare r record;
q1 bigint := 42;
begin
for r in select q1,q2 from int8_tbl loop
return next r;
end loop;
end;
$$ language plpgsql;
select * from conflict_test();
q1 | q2
------------------+-------------------
123 | 456
123 | 4567890123456789
4567890123456789 | 123
4567890123456789 | 4567890123456789
4567890123456789 | -4567890123456789
(5 rows)
drop function conflict_test();
-- Check that an unreserved keyword can be used as a variable name
create function unreserved_test() returns int as $$

28
src/test/regress/sql/plpgsql.sql
View File

@ -3176,6 +3176,8 @@ drop function scope_test();
-- Check handling of conflicts between plpgsql vars and table columns.
set plpgsql.variable_conflict = error;
create function conflict_test() returns setof int8_tbl as $$
declare r record;
q1 bigint := 42;
@ -3188,6 +3190,32 @@ $$ language plpgsql;
select * from conflict_test();
create or replace function conflict_test() returns setof int8_tbl as $$
#variable_conflict use_variable
declare r record;
q1 bigint := 42;
begin
for r in select q1,q2 from int8_tbl loop
return next r;
end loop;
end;
$$ language plpgsql;
select * from conflict_test();
create or replace function conflict_test() returns setof int8_tbl as $$
#variable_conflict use_column
declare r record;
q1 bigint := 42;
begin
for r in select q1,q2 from int8_tbl loop
return next r;
end loop;
end;
$$ language plpgsql;
select * from conflict_test();
drop function conflict_test();
-- Check that an unreserved keyword can be used as a variable name