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Allow SQL-language functions to return the output of an INSERT/UPDATE/DELETE

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RETURNING clause, not just a SELECT as formerly.

A side effect of this patch is that when a set-returning SQL function is used
in a FROM clause, performance is improved because the output is collected into
a tuplestore within the function, rather than using the less efficient
value-per-call mechanism.
REL8_5_ALPHA1_BRANCH
Tom Lane 17 years ago
parent cd97f98844
commit 9b46abb7c4
11 changed files with 830 additions and 309 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 51
      doc/src/sgml/xfunc.sgml
  2. 60
      src/backend/executor/execQual.c
  3. 676
      src/backend/executor/functions.c
  4. 9
      src/backend/tcop/dest.c
  5. 6
      src/backend/utils/fmgr/README
  6. 5
      src/include/executor/functions.h
  7. 8
      src/include/nodes/execnodes.h
  8. 5
      src/include/tcop/dest.h
  9. 176
      src/test/regress/expected/rangefuncs.out
  10. 2
      src/test/regress/output/create_function_1.source
  11. 59
      src/test/regress/sql/rangefuncs.sql

51
doc/src/sgml/xfunc.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.132 2008/07/18 03:32:52 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.133 2008/10/31 19:37:56 tgl Exp $ -->
<sect1 id="xfunc">
<title>User-Defined Functions</title>
@ -106,7 +106,9 @@
The body of an SQL function must be a list of SQL
statements separated by semicolons. A semicolon after the last
statement is optional. Unless the function is declared to return
<type>void</>, the last statement must be a <command>SELECT</>.
<type>void</>, the last statement must be a <command>SELECT</>,
or an <command>INSERT</>, <command>UPDATE</>, or <command>DELETE</>
that has a <literal>RETURNING</> clause.
</para>
<para>
@ -119,11 +121,11 @@
<command>BEGIN</>, <command>COMMIT</>, <command>ROLLBACK</>, or
<command>SAVEPOINT</> commands into a <acronym>SQL</acronym> function.)
However, the final command
must be a <command>SELECT</command> that returns whatever is
must be a <command>SELECT</command> or have a <literal>RETURNING</>
clause that returns whatever is
specified as the function's return type. Alternatively, if you
want to define a SQL function that performs actions but has no
useful value to return, you can define it as returning <type>void</>.
In that case, the function body must not end with a <command>SELECT</command>.
For example, this function removes rows with negative salaries from
the <literal>emp</> table:
@ -257,6 +259,16 @@ $$ LANGUAGE SQL;
</programlisting>
which adjusts the balance and returns the new balance.
The same thing could be done in one command using <literal>RETURNING</>:
<programlisting>
CREATE FUNCTION tf1 (integer, numeric) RETURNS numeric AS $$
UPDATE bank
SET balance = balance - $2
WHERE accountno = $1
RETURNING balance;
$$ LANGUAGE SQL;
</programlisting>
</para>
</sect2>
@ -422,7 +434,7 @@ SELECT (new_emp()).name;
<screen>
SELECT new_emp().name;
ERROR: syntax error at or near "." at character 17
ERROR: syntax error at or near "."
LINE 1: SELECT new_emp().name;
^
</screen>
@ -705,7 +717,7 @@ SELECT *, upper(fooname) FROM getfoo(1) AS t1;
<para>
When an SQL function is declared as returning <literal>SETOF
<replaceable>sometype</></literal>, the function's final
<command>SELECT</> query is executed to completion, and each row it
query is executed to completion, and each row it
outputs is returned as an element of the result set.
</para>
@ -798,6 +810,18 @@ SELECT name, listchildren(name) FROM nodes;
This happens because <function>listchildren</function> returns an empty set
for those arguments, so no result rows are generated.
</para>
<note>
<para>
If a function's last command is <command>INSERT</>, <command>UPDATE</>,
or <command>DELETE</> with <literal>RETURNING</>, that command will
always be executed to completion, even if the function is not declared
with <literal>SETOF</> or the calling query does not fetch all the
result rows. Any extra rows produced by the <literal>RETURNING</>
clause are silently dropped, but the commanded table modifications
still happen (and are all completed before returning from the function).
</para>
</note>
</sect2>
<sect2 id="xfunc-sql-functions-returning-table">
@ -1459,15 +1483,12 @@ PG_MODULE_MAGIC;
<para>
By-value types can only be 1, 2, or 4 bytes in length
(also 8 bytes, if <literal>sizeof(Datum)</literal> is 8 on your machine).
You should be careful
to define your types such that they will be the same
size (in bytes) on all architectures. For example, the
<literal>long</literal> type is dangerous because it
is 4 bytes on some machines and 8 bytes on others, whereas
<type>int</type> type is 4 bytes on most
Unix machines. A reasonable implementation of
the <type>int4</type> type on Unix
machines might be:
You should be careful to define your types such that they will be the
same size (in bytes) on all architectures. For example, the
<literal>long</literal> type is dangerous because it is 4 bytes on some
machines and 8 bytes on others, whereas <type>int</type> type is 4 bytes
on most Unix machines. A reasonable implementation of the
<type>int4</type> type on Unix machines might be:
<programlisting>
/* 4-byte integer, passed by value */

60
src/backend/executor/execQual.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.235 2008/10/29 00:00:38 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.236 2008/10/31 19:37:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1334,7 +1334,8 @@ ExecMakeFunctionResult(FuncExprState *fcache,
{
List *arguments;
Datum result;
FunctionCallInfoData fcinfo;
FunctionCallInfoData fcinfo_data;
FunctionCallInfo fcinfo;
PgStat_FunctionCallUsage fcusage;
ReturnSetInfo rsinfo; /* for functions returning sets */
ExprDoneCond argDone;
@ -1384,6 +1385,20 @@ restart:
Assert(!fcache->setArgsValid);
}
/*
* For non-set-returning functions, we just use a local-variable
* FunctionCallInfoData. For set-returning functions we keep the callinfo
* record in fcache->setArgs so that it can survive across multiple
* value-per-call invocations. (The reason we don't just do the latter
* all the time is that plpgsql expects to be able to use simple expression
* trees re-entrantly. Which might not be a good idea, but the penalty
* for not doing so is high.)
*/
if (fcache->func.fn_retset)
fcinfo = &fcache->setArgs;
else
fcinfo = &fcinfo_data;
/*
* arguments is a list of expressions to evaluate before passing to the
* function manager. We skip the evaluation if it was already done in the
@ -1394,8 +1409,8 @@ restart:
if (!fcache->setArgsValid)
{
/* Need to prep callinfo structure */
InitFunctionCallInfoData(fcinfo, &(fcache->func), 0, NULL, NULL);
argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);
InitFunctionCallInfoData(*fcinfo, &(fcache->func), 0, NULL, NULL);
argDone = ExecEvalFuncArgs(fcinfo, arguments, econtext);
if (argDone == ExprEndResult)
{
/* input is an empty set, so return an empty set. */
@ -1412,8 +1427,7 @@ restart:
}
else
{
/* Copy callinfo from previous evaluation */
memcpy(&fcinfo, &fcache->setArgs, sizeof(fcinfo));
/* Re-use callinfo from previous evaluation */
hasSetArg = fcache->setHasSetArg;
/* Reset flag (we may set it again below) */
fcache->setArgsValid = false;
@ -1424,12 +1438,12 @@ restart:
*/
if (fcache->func.fn_retset)
{
fcinfo.resultinfo = (Node *) &rsinfo;
fcinfo->resultinfo = (Node *) &rsinfo;
rsinfo.type = T_ReturnSetInfo;
rsinfo.econtext = econtext;
rsinfo.expectedDesc = fcache->funcResultDesc;
rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize);
/* note we do not set SFRM_Materialize_Random */
/* note we do not set SFRM_Materialize_Random or _Preferred */
rsinfo.returnMode = SFRM_ValuePerCall;
/* isDone is filled below */
rsinfo.setResult = NULL;
@ -1468,9 +1482,9 @@ restart:
if (fcache->func.fn_strict)
{
for (i = 0; i < fcinfo.nargs; i++)
for (i = 0; i < fcinfo->nargs; i++)
{
if (fcinfo.argnull[i])
if (fcinfo->argnull[i])
{
callit = false;
break;
@ -1480,12 +1494,12 @@ restart:
if (callit)
{
pgstat_init_function_usage(&fcinfo, &fcusage);
pgstat_init_function_usage(fcinfo, &fcusage);
fcinfo.isnull = false;
fcinfo->isnull = false;
rsinfo.isDone = ExprSingleResult;
result = FunctionCallInvoke(&fcinfo);
*isNull = fcinfo.isnull;
result = FunctionCallInvoke(fcinfo);
*isNull = fcinfo->isnull;
*isDone = rsinfo.isDone;
pgstat_end_function_usage(&fcusage,
@ -1511,7 +1525,7 @@ restart:
if (fcache->func.fn_retset &&
*isDone == ExprMultipleResult)
{
memcpy(&fcache->setArgs, &fcinfo, sizeof(fcinfo));
Assert(fcinfo == &fcache->setArgs);
fcache->setHasSetArg = hasSetArg;
fcache->setArgsValid = true;
/* Register cleanup callback if we didn't already */
@ -1567,7 +1581,7 @@ restart:
break; /* input not a set, so done */
/* Re-eval args to get the next element of the input set */
argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);
argDone = ExecEvalFuncArgs(fcinfo, arguments, econtext);
if (argDone != ExprMultipleResult)
{
@ -1605,9 +1619,9 @@ restart:
*/
if (fcache->func.fn_strict)
{
for (i = 0; i < fcinfo.nargs; i++)
for (i = 0; i < fcinfo->nargs; i++)
{
if (fcinfo.argnull[i])
if (fcinfo->argnull[i])
{
*isNull = true;
return (Datum) 0;
@ -1615,11 +1629,11 @@ restart:
}
}
pgstat_init_function_usage(&fcinfo, &fcusage);
pgstat_init_function_usage(fcinfo, &fcusage);
fcinfo.isnull = false;
result = FunctionCallInvoke(&fcinfo);
*isNull = fcinfo.isnull;
fcinfo->isnull = false;
result = FunctionCallInvoke(fcinfo);
*isNull = fcinfo->isnull;
pgstat_end_function_usage(&fcusage, true);
}
@ -1737,7 +1751,7 @@ ExecMakeTableFunctionResult(ExprState *funcexpr,
rsinfo.type = T_ReturnSetInfo;
rsinfo.econtext = econtext;
rsinfo.expectedDesc = expectedDesc;
rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize);
rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize | SFRM_Materialize_Preferred);
if (randomAccess)
rsinfo.allowedModes |= (int) SFRM_Materialize_Random;
rsinfo.returnMode = SFRM_ValuePerCall;

676
src/backend/executor/functions.c
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File diff suppressed because it is too large Load Diff

9
src/backend/tcop/dest.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/dest.c,v 1.72 2008/01/01 19:45:52 momjian Exp $
* $PostgreSQL: pgsql/src/backend/tcop/dest.c,v 1.73 2008/10/31 19:37:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -32,6 +32,7 @@
#include "access/xact.h"
#include "commands/copy.h"
#include "executor/executor.h"
#include "executor/functions.h"
#include "executor/tstoreReceiver.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
@ -132,6 +133,9 @@ CreateDestReceiver(CommandDest dest, Portal portal)
case DestCopyOut:
return CreateCopyDestReceiver();
case DestSQLFunction:
return CreateSQLFunctionDestReceiver();
}
/* should never get here */
@ -158,6 +162,7 @@ EndCommand(const char *commandTag, CommandDest dest)
case DestTuplestore:
case DestIntoRel:
case DestCopyOut:
case DestSQLFunction:
break;
}
}
@ -198,6 +203,7 @@ NullCommand(CommandDest dest)
case DestTuplestore:
case DestIntoRel:
case DestCopyOut:
case DestSQLFunction:
break;
}
}
@ -240,6 +246,7 @@ ReadyForQuery(CommandDest dest)
case DestTuplestore:
case DestIntoRel:
case DestCopyOut:
case DestSQLFunction:
break;
}
}

6
src/backend/utils/fmgr/README
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@ -1,4 +1,4 @@
$PostgreSQL: pgsql/src/backend/utils/fmgr/README,v 1.15 2008/10/29 00:00:38 tgl Exp $
$PostgreSQL: pgsql/src/backend/utils/fmgr/README,v 1.16 2008/10/31 19:37:56 tgl Exp $
Function Manager
================
@ -434,7 +434,9 @@ and returns null. isDone is not used and should be left at ExprSingleResult.
The Tuplestore must be created with randomAccess = true if
SFRM_Materialize_Random is set in allowedModes, but it can (and preferably
should) be created with randomAccess = false if not.
should) be created with randomAccess = false if not. Callers that can support
both ValuePerCall and Materialize mode will set SFRM_Materialize_Preferred,
or not, depending on which mode they prefer.
If available, the expected tuple descriptor is passed in ReturnSetInfo;
in other contexts the expectedDesc field will be NULL. The function need

5
src/include/executor/functions.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/executor/functions.h,v 1.31 2008/03/18 22:04:14 tgl Exp $
* $PostgreSQL: pgsql/src/include/executor/functions.h,v 1.32 2008/10/31 19:37:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -15,6 +15,7 @@
#define FUNCTIONS_H
#include "nodes/execnodes.h"
#include "tcop/dest.h"
extern Datum fmgr_sql(PG_FUNCTION_ARGS);
@ -24,4 +25,6 @@ extern bool check_sql_fn_retval(Oid func_id, Oid rettype,
bool insertRelabels,
JunkFilter **junkFilter);
extern DestReceiver *CreateSQLFunctionDestReceiver(void);
#endif /* FUNCTIONS_H */

8
src/include/nodes/execnodes.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.193 2008/10/29 00:00:39 tgl Exp $
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.194 2008/10/31 19:37:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -151,13 +151,15 @@ typedef enum
/*
* Return modes for functions returning sets. Note values must be chosen
* as separate bits so that a bitmask can be formed to indicate supported
* modes.
* modes. SFRM_Materialize_Random and SFRM_Materialize_Preferred are
* auxiliary flags about SFRM_Materialize mode, rather than separate modes.
*/
typedef enum
{
SFRM_ValuePerCall = 0x01, /* one value returned per call */
SFRM_Materialize = 0x02, /* result set instantiated in Tuplestore */
SFRM_Materialize_Random = 0x04 /* Tuplestore needs randomAccess */
SFRM_Materialize_Random = 0x04, /* Tuplestore needs randomAccess */
SFRM_Materialize_Preferred = 0x08 /* caller prefers Tuplestore */
} SetFunctionReturnMode;
/*

5
src/include/tcop/dest.h
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@ -54,7 +54,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/tcop/dest.h,v 1.54 2008/01/01 19:45:59 momjian Exp $
* $PostgreSQL: pgsql/src/include/tcop/dest.h,v 1.55 2008/10/31 19:37:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -86,7 +86,8 @@ typedef enum
DestSPI, /* results sent to SPI manager */
DestTuplestore, /* results sent to Tuplestore */
DestIntoRel, /* results sent to relation (SELECT INTO) */
DestCopyOut /* results sent to COPY TO code */
DestCopyOut, /* results sent to COPY TO code */
DestSQLFunction /* results sent to SQL-language func mgr */
} CommandDest;
/* ----------------

176
src/test/regress/expected/rangefuncs.out
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@ -567,3 +567,179 @@ SELECT * FROM foo(3);
(9 rows)
DROP FUNCTION foo(int);
--
-- some tests on SQL functions with RETURNING
--
create temp table tt(f1 serial, data text);
NOTICE: CREATE TABLE will create implicit sequence "tt_f1_seq" for serial column "tt.f1"
create function insert_tt(text) returns int as
$$ insert into tt(data) values($1) returning f1 $$
language sql;
select insert_tt('foo');
insert_tt
-----------
1
(1 row)
select insert_tt('bar');
insert_tt
-----------
2
(1 row)
select * from tt;
f1 | data
----+------
1 | foo
2 | bar
(2 rows)
-- insert will execute to completion even if function needs just 1 row
create or replace function insert_tt(text) returns int as
$$ insert into tt(data) values($1),($1||$1) returning f1 $$
language sql;
select insert_tt('fool');
insert_tt
-----------
3
(1 row)
select * from tt;
f1 | data
----+----------
1 | foo
2 | bar
3 | fool
4 | foolfool
(4 rows)
-- setof does what's expected
create or replace function insert_tt2(text,text) returns setof int as
$$ insert into tt(data) values($1),($2) returning f1 $$
language sql;
select insert_tt2('foolish','barrish');
insert_tt2
------------
5
6
(2 rows)
select * from insert_tt2('baz','quux');
insert_tt2
------------
7
8
(2 rows)
select * from tt;
f1 | data
----+----------
1 | foo
2 | bar
3 | fool
4 | foolfool
5 | foolish
6 | barrish
7 | baz
8 | quux
(8 rows)
-- limit doesn't prevent execution to completion
select insert_tt2('foolish','barrish') limit 1;
insert_tt2
------------
9
(1 row)
select * from tt;
f1 | data
----+----------
1 | foo
2 | bar
3 | fool
4 | foolfool
5 | foolish
6 | barrish
7 | baz
8 | quux
9 | foolish
10 | barrish
(10 rows)
-- triggers will fire, too
create function noticetrigger() returns trigger as $$
begin
raise notice 'noticetrigger % %', new.f1, new.data;
return null;
end $$ language plpgsql;
create trigger tnoticetrigger after insert on tt for each row
execute procedure noticetrigger();
select insert_tt2('foolme','barme') limit 1;
NOTICE: noticetrigger 11 foolme
CONTEXT: SQL function "insert_tt2" statement 1
NOTICE: noticetrigger 12 barme
CONTEXT: SQL function "insert_tt2" statement 1
insert_tt2
------------
11
(1 row)
select * from tt;
f1 | data
----+----------
1 | foo
2 | bar
3 | fool
4 | foolfool
5 | foolish
6 | barrish
7 | baz
8 | quux
9 | foolish
10 | barrish
11 | foolme
12 | barme
(12 rows)
-- and rules work
create temp table tt_log(f1 int, data text);
create rule insert_tt_rule as on insert to tt do also
insert into tt_log values(new.*);
select insert_tt2('foollog','barlog') limit 1;
NOTICE: noticetrigger 13 foollog
CONTEXT: SQL function "insert_tt2" statement 1
NOTICE: noticetrigger 14 barlog
CONTEXT: SQL function "insert_tt2" statement 1
insert_tt2
------------
13
(1 row)
select * from tt;
f1 | data
----+----------
1 | foo
2 | bar
3 | fool
4 | foolfool
5 | foolish
6 | barrish
7 | baz
8 | quux
9 | foolish
10 | barrish
11 | foolme
12 | barme
13 | foollog
14 | barlog
(14 rows)
-- note that nextval() gets executed a second time in the rule expansion,
-- which is expected.
select * from tt_log;
f1 | data
----+---------
15 | foollog
16 | barlog
(2 rows)

2
src/test/regress/output/create_function_1.source
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@ -61,7 +61,7 @@ LINE 2: AS 'not even SQL';
CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
AS 'SELECT 1, 2, 3;';
ERROR: return type mismatch in function declared to return integer
DETAIL: Final SELECT must return exactly one column.
DETAIL: Final statement must return exactly one column.
CONTEXT: SQL function "test1"
CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
AS 'SELECT $2;';

59
src/test/regress/sql/rangefuncs.sql
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@ -279,3 +279,62 @@ AS $$ SELECT a, b
generate_series(1,$1) b(b) $$ LANGUAGE sql;
SELECT * FROM foo(3);
DROP FUNCTION foo(int);
--
-- some tests on SQL functions with RETURNING
--
create temp table tt(f1 serial, data text);
create function insert_tt(text) returns int as
$$ insert into tt(data) values($1) returning f1 $$
language sql;
select insert_tt('foo');
select insert_tt('bar');
select * from tt;
-- insert will execute to completion even if function needs just 1 row
create or replace function insert_tt(text) returns int as
$$ insert into tt(data) values($1),($1||$1) returning f1 $$
language sql;
select insert_tt('fool');
select * from tt;
-- setof does what's expected
create or replace function insert_tt2(text,text) returns setof int as
$$ insert into tt(data) values($1),($2) returning f1 $$
language sql;
select insert_tt2('foolish','barrish');
select * from insert_tt2('baz','quux');
select * from tt;
-- limit doesn't prevent execution to completion
select insert_tt2('foolish','barrish') limit 1;
select * from tt;
-- triggers will fire, too
create function noticetrigger() returns trigger as $$
begin
raise notice 'noticetrigger % %', new.f1, new.data;
return null;
end $$ language plpgsql;
create trigger tnoticetrigger after insert on tt for each row
execute procedure noticetrigger();
select insert_tt2('foolme','barme') limit 1;
select * from tt;
-- and rules work
create temp table tt_log(f1 int, data text);
create rule insert_tt_rule as on insert to tt do also
insert into tt_log values(new.*);
select insert_tt2('foollog','barlog') limit 1;
select * from tt;
-- note that nextval() gets executed a second time in the rule expansion,
-- which is expected.
select * from tt_log;

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