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Add support for invoking parser callback hooks via SPI and in cached plans.
As proof of concept, modify plpgsql to use the hooks. plpgsql is still inserting $n symbols textually, but the "back end" of the parsing process now goes through the ParamRef hook instead of using a fixed parameter-type array, and then execution only fetches actually-referenced parameters, using a hook added to ParamListInfo. Although there's a lot left to be done in plpgsql, this already cures the "if (TG_OP = 'INSERT' and NEW.foo ...)" problem, as illustrated by the changed regression test.
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‎doc/src/sgml/spi.sgml

Lines changed: 281 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.65 2009/08/05 19:31:50 alvherre Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.66 2009/11/04 22:26:04 tgl Exp $ -->
22

33
<chapter id="spi">
44
<title>Server Programming Interface</title>
@@ -861,7 +861,7 @@ SPIPlanPtr SPI_prepare(const char * <parameter>command</parameter>, int <paramet
861861

862862
<para>
863863
<function>SPI_prepare</function> creates and returns an execution
864-
plan for the specified command but doesn't execute the command.
864+
plan for the specified command, but doesn't execute the command.
865865
This function should only be called from a connected procedure.
866866
</para>
867867

@@ -990,7 +990,7 @@ SPIPlanPtr SPI_prepare_cursor(const char * <parameter>command</parameter>, int <
990990
of the planner's <quote>cursor options</> parameter. This is a bitmask
991991
having the values shown in <filename>nodes/parsenodes.h</filename>
992992
for the <structfield>options</> field of <structname>DeclareCursorStmt</>.
993-
<function>SPI_prepare</function> always takes these options as zero.
993+
<function>SPI_prepare</function> always takes the cursor options as zero.
994994
</para>
995995
</refsect1>
996996

@@ -1061,6 +1061,94 @@ SPIPlanPtr SPI_prepare_cursor(const char * <parameter>command</parameter>, int <
10611061

10621062
<!-- *********************************************** -->
10631063

1064+
<refentry id="spi-spi-prepare-params">
1065+
<refmeta>
1066+
<refentrytitle>SPI_prepare_params</refentrytitle>
1067+
<manvolnum>3</manvolnum>
1068+
</refmeta>
1069+
1070+
<refnamediv>
1071+
<refname>SPI_prepare_params</refname>
1072+
<refpurpose>prepare a plan for a command, without executing it yet</refpurpose>
1073+
</refnamediv>
1074+
1075+
<indexterm><primary>SPI_prepare_params</primary></indexterm>
1076+
1077+
<refsynopsisdiv>
1078+
<synopsis>
1079+
SPIPlanPtr SPI_prepare_params(const char * <parameter>command</parameter>,
1080+
ParserSetupHook <parameter>parserSetup</parameter>,
1081+
void * <parameter>parserSetupArg</parameter>,
1082+
int <parameter>cursorOptions</parameter>)
1083+
</synopsis>
1084+
</refsynopsisdiv>
1085+
1086+
<refsect1>
1087+
<title>Description</title>
1088+
1089+
<para>
1090+
<function>SPI_prepare_params</function> creates and returns an execution
1091+
plan for the specified command, but doesn't execute the command.
1092+
This function is equivalent to <function>SPI_prepare_cursor</function>,
1093+
with the addition that the caller can specify parser hook functions
1094+
to control the parsing of external parameter references.
1095+
</para>
1096+
</refsect1>
1097+
1098+
<refsect1>
1099+
<title>Arguments</title>
1100+
1101+
<variablelist>
1102+
<varlistentry>
1103+
<term><literal>const char * <parameter>command</parameter></literal></term>
1104+
<listitem>
1105+
<para>
1106+
command string
1107+
</para>
1108+
</listitem>
1109+
</varlistentry>
1110+
1111+
<varlistentry>
1112+
<term><literal>ParserSetupHook <parameter>parserSetup</parameter></literal></term>
1113+
<listitem>
1114+
<para>
1115+
Parser hook setup function
1116+
</para>
1117+
</listitem>
1118+
</varlistentry>
1119+
1120+
<varlistentry>
1121+
<term><literal>void * <parameter>parserSetupArg</parameter></literal></term>
1122+
<listitem>
1123+
<para>
1124+
passthrough argument for <parameter>parserSetup</parameter>
1125+
</para>
1126+
</listitem>
1127+
</varlistentry>
1128+
1129+
<varlistentry>
1130+
<term><literal>int <parameter>cursorOptions</parameter></literal></term>
1131+
<listitem>
1132+
<para>
1133+
integer bitmask of cursor options; zero produces default behavior
1134+
</para>
1135+
</listitem>
1136+
</varlistentry>
1137+
</variablelist>
1138+
</refsect1>
1139+
1140+
<refsect1>
1141+
<title>Return Value</title>
1142+
1143+
<para>
1144+
<function>SPI_prepare_params</function> has the same return conventions as
1145+
<function>SPI_prepare</function>.
1146+
</para>
1147+
</refsect1>
1148+
</refentry>
1149+
1150+
<!-- *********************************************** -->
1151+
10641152
<refentry id="spi-spi-getargcount">
10651153
<refmeta>
10661154
<refentrytitle>SPI_getargcount</refentrytitle>
@@ -1386,14 +1474,100 @@ int SPI_execute_plan(SPIPlanPtr <parameter>plan</parameter>, Datum * <parameter>
13861474
<function>SPI_execute</function> if successful.
13871475
</para>
13881476
</refsect1>
1477+
</refentry>
1478+
1479+
<!-- *********************************************** -->
1480+
1481+
<refentry id="spi-spi-execute-plan-with-paramlist">
1482+
<refmeta>
1483+
<refentrytitle>SPI_execute_plan_with_paramlist</refentrytitle>
1484+
<manvolnum>3</manvolnum>
1485+
</refmeta>
1486+
1487+
<refnamediv>
1488+
<refname>SPI_execute_plan_with_paramlist</refname>
1489+
<refpurpose>execute a plan prepared by <function>SPI_prepare</function></refpurpose>
1490+
</refnamediv>
1491+
1492+
<indexterm><primary>SPI_execute_plan_with_paramlist</primary></indexterm>
1493+
1494+
<refsynopsisdiv>
1495+
<synopsis>
1496+
int SPI_execute_plan_with_paramlist(SPIPlanPtr <parameter>plan</parameter>,
1497+
ParamListInfo <parameter>params</parameter>,
1498+
bool <parameter>read_only</parameter>,
1499+
long <parameter>count</parameter>)
1500+
</synopsis>
1501+
</refsynopsisdiv>
13891502

13901503
<refsect1>
1391-
<title>Notes</title>
1504+
<title>Description</title>
13921505

13931506
<para>
1394-
If one of the objects (a table, function, etc.) referenced by the
1395-
prepared plan is dropped during the session then the result of
1396-
<function>SPI_execute_plan</function> for this plan will be unpredictable.
1507+
<function>SPI_execute_plan_with_paramlist</function> executes a plan
1508+
prepared by <function>SPI_prepare</function>.
1509+
This function is equivalent to <function>SPI_execute_plan</function>
1510+
except that information about the parameter values to be passed to the
1511+
query is presented differently. The <literal>ParamListInfo</>
1512+
representation can be convenient for passing down values that are
1513+
already available in that format. It also supports use of dynamic
1514+
parameter sets via hook functions specified in <literal>ParamListInfo</>.
1515+
</para>
1516+
</refsect1>
1517+
1518+
<refsect1>
1519+
<title>Arguments</title>
1520+
1521+
<variablelist>
1522+
<varlistentry>
1523+
<term><literal>SPIPlanPtr <parameter>plan</parameter></literal></term>
1524+
<listitem>
1525+
<para>
1526+
execution plan (returned by <function>SPI_prepare</function>)
1527+
</para>
1528+
</listitem>
1529+
</varlistentry>
1530+
1531+
<varlistentry>
1532+
<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
1533+
<listitem>
1534+
<para>
1535+
data structure containing parameter types and values; NULL if none
1536+
</para>
1537+
</listitem>
1538+
</varlistentry>
1539+
1540+
<varlistentry>
1541+
<term><literal>bool <parameter>read_only</parameter></literal></term>
1542+
<listitem>
1543+
<para>
1544+
<literal>true</> for read-only execution
1545+
</para>
1546+
</listitem>
1547+
</varlistentry>
1548+
1549+
<varlistentry>
1550+
<term><literal>long <parameter>count</parameter></literal></term>
1551+
<listitem>
1552+
<para>
1553+
maximum number of rows to process or return
1554+
</para>
1555+
</listitem>
1556+
</varlistentry>
1557+
</variablelist>
1558+
</refsect1>
1559+
1560+
<refsect1>
1561+
<title>Return Value</title>
1562+
1563+
<para>
1564+
The return value is the same as for <function>SPI_execute_plan</function>.
1565+
</para>
1566+
1567+
<para>
1568+
<varname>SPI_processed</varname> and
1569+
<varname>SPI_tuptable</varname> are set as in
1570+
<function>SPI_execute_plan</function> if successful.
13971571
</para>
13981572
</refsect1>
13991573
</refentry>
@@ -1543,7 +1717,7 @@ Portal SPI_cursor_open(const char * <parameter>name</parameter>, SPIPlanPtr <par
15431717
</para>
15441718

15451719
<para>
1546-
The passed-in data will be copied into the cursor's portal, so it
1720+
The passed-in parameter data will be copied into the cursor's portal, so it
15471721
can be freed while the cursor still exists.
15481722
</para>
15491723
</refsect1>
@@ -1667,7 +1841,7 @@ Portal SPI_cursor_open_with_args(const char *<parameter>name</parameter>,
16671841
</para>
16681842

16691843
<para>
1670-
The passed-in data will be copied into the cursor's portal, so it
1844+
The passed-in parameter data will be copied into the cursor's portal, so it
16711845
can be freed while the cursor still exists.
16721846
</para>
16731847
</refsect1>
@@ -1770,6 +1944,104 @@ Portal SPI_cursor_open_with_args(const char *<parameter>name</parameter>,
17701944

17711945
<!-- *********************************************** -->
17721946

1947+
<refentry id="spi-spi-cursor-open-with-paramlist">
1948+
<refmeta>
1949+
<refentrytitle>SPI_cursor_open_with_paramlist</refentrytitle>
1950+
<manvolnum>3</manvolnum>
1951+
</refmeta>
1952+
1953+
<refnamediv>
1954+
<refname>SPI_cursor_open_with_paramlist</refname>
1955+
<refpurpose>set up a cursor using parameters</refpurpose>
1956+
</refnamediv>
1957+
1958+
<indexterm><primary>SPI_cursor_open_with_paramlist</primary></indexterm>
1959+
1960+
<refsynopsisdiv>
1961+
<synopsis>
1962+
Portal SPI_cursor_open_with_paramlist(const char *<parameter>name</parameter>,
1963+
SPIPlanPtr <parameter>plan</parameter>,
1964+
ParamListInfo <parameter>params</parameter>,
1965+
bool <parameter>read_only</parameter>)
1966+
</synopsis>
1967+
</refsynopsisdiv>
1968+
1969+
<refsect1>
1970+
<title>Description</title>
1971+
1972+
<para>
1973+
<function>SPI_cursor_open_with_paramlist</function> sets up a cursor
1974+
(internally, a portal) that will execute a plan prepared by
1975+
<function>SPI_prepare</function>.
1976+
This function is equivalent to <function>SPI_cursor_open</function>
1977+
except that information about the parameter values to be passed to the
1978+
query is presented differently. The <literal>ParamListInfo</>
1979+
representation can be convenient for passing down values that are
1980+
already available in that format. It also supports use of dynamic
1981+
parameter sets via hook functions specified in <literal>ParamListInfo</>.
1982+
</para>
1983+
1984+
<para>
1985+
The passed-in parameter data will be copied into the cursor's portal, so it
1986+
can be freed while the cursor still exists.
1987+
</para>
1988+
</refsect1>
1989+
1990+
<refsect1>
1991+
<title>Arguments</title>
1992+
1993+
<variablelist>
1994+
<varlistentry>
1995+
<term><literal>const char * <parameter>name</parameter></literal></term>
1996+
<listitem>
1997+
<para>
1998+
name for portal, or <symbol>NULL</symbol> to let the system
1999+
select a name
2000+
</para>
2001+
</listitem>
2002+
</varlistentry>
2003+
2004+
<varlistentry>
2005+
<term><literal>SPIPlanPtr <parameter>plan</parameter></literal></term>
2006+
<listitem>
2007+
<para>
2008+
execution plan (returned by <function>SPI_prepare</function>)
2009+
</para>
2010+
</listitem>
2011+
</varlistentry>
2012+
2013+
<varlistentry>
2014+
<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
2015+
<listitem>
2016+
<para>
2017+
data structure containing parameter types and values; NULL if none
2018+
</para>
2019+
</listitem>
2020+
</varlistentry>
2021+
2022+
<varlistentry>
2023+
<term><literal>bool <parameter>read_only</parameter></literal></term>
2024+
<listitem>
2025+
<para>
2026+
<literal>true</> for read-only execution
2027+
</para>
2028+
</listitem>
2029+
</varlistentry>
2030+
</variablelist>
2031+
</refsect1>
2032+
2033+
<refsect1>
2034+
<title>Return Value</title>
2035+
2036+
<para>
2037+
Pointer to portal containing the cursor. Note there is no error
2038+
return convention; any error will be reported via <function>elog</>.
2039+
</para>
2040+
</refsect1>
2041+
</refentry>
2042+
2043+
<!-- *********************************************** -->
2044+
17732045
<refentry id="spi-spi-cursor-find">
17742046
<refmeta>
17752047
<refentrytitle>SPI_cursor_find</refentrytitle>

‎src/backend/commands/explain.c

Lines changed: 5 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994-5, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.192 2009/10/12 18:10:41 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.193 2009/11/04 22:26:04 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -107,8 +107,6 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
107107
ParamListInfo params, DestReceiver *dest)
108108
{
109109
ExplainState es;
110-
Oid *param_types;
111-
int num_params;
112110
TupOutputState *tstate;
113111
List *rewritten;
114112
ListCell *lc;
@@ -150,9 +148,6 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
150148
opt->defname)));
151149
}
152150

153-
/* Convert parameter type data to the form parser wants */
154-
getParamListTypes(params, &param_types, &num_params);
155-
156151
/*
157152
* Run parse analysis and rewrite. Note this also acquires sufficient
158153
* locks on the source table(s).
@@ -163,8 +158,10 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
163158
* executed repeatedly. (See also the same hack in DECLARE CURSOR and
164159
* PREPARE.) XXX FIXME someday.
165160
*/
166-
rewritten = pg_analyze_and_rewrite((Node *) copyObject(stmt->query),
167-
queryString, param_types, num_params);
161+
rewritten = pg_analyze_and_rewrite_params((Node *) copyObject(stmt->query),
162+
queryString,
163+
(ParserSetupHook) setupParserWithParamList,
164+
params);
168165

169166
/* emit opening boilerplate */
170167
ExplainBeginOutput(&es);

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