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Avoid using a cursor in plpgsql's RETURN QUERY statement.

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plpgsql has always executed the query given in a RETURN QUERY command
by opening it as a cursor and then fetching a few rows at a time,
which it turns around and dumps into the function's result tuplestore.
The point of this was to keep from blowing out memory with an oversized
SPITupleTable result (note that while a tuplestore can spill tuples
to disk, SPITupleTable cannot).  However, it's rather inefficient, both
because of extra data copying and because of executor entry/exit
overhead.  In recent versions, a new performance problem has emerged:
use of a cursor prevents use of a parallel plan for the executed query.

We can improve matters by skipping use of a cursor and having the
executor push result tuples directly into the function's result
tuplestore.  However, a moderate amount of new infrastructure is needed
to make that idea work:

* We can use the existing tstoreReceiver.c DestReceiver code to funnel
executor output to the tuplestore, but it has to be extended to support
plpgsql's requirement for possibly applying a tuple conversion map.

* SPI needs to be extended to allow use of a caller-supplied
DestReceiver instead of its usual receiver that puts tuples into
a SPITupleTable.  Two new API calls are needed to handle both the
RETURN QUERY and RETURN QUERY EXECUTE cases.

I also felt that I didn't want these new API calls to use the legacy
method of specifying query parameter values with "char" null flags
(the old ' '/'n' convention); rather they should accept ParamListInfo
objects containing the parameter type and value info.  This required
a bit of additional new infrastructure since we didn't yet have any
parse analysis callback that would interpret $N parameter symbols
according to type data supplied in a ParamListInfo.  There seems to be
no harm in letting makeParamList install that callback by default,
rather than leaving a new ParamListInfo's parserSetup hook as NULL.
(Indeed, as of HEAD, I couldn't find anyplace that was using the
parserSetup field at all; plpgsql was using parserSetupArg for its
own purposes, but parserSetup seemed to be write-only.)

We can actually get plpgsql out of the business of using legacy null
flags altogether, and using ParamListInfo instead of its ad-hoc
PreparedParamsData structure; but this requires inventing one more
SPI API call that can replace SPI_cursor_open_with_args.  That seems
worth doing, though.

SPI_execute_with_args and SPI_cursor_open_with_args are now unused
anywhere in the core PG distribution.  Perhaps someday we could
deprecate/remove them.  But cleaning up the crufty bits of the SPI
API is a task for a different patch.

Per bug #16040 from Jeremy Smith.  This is unfortunately too invasive to
consider back-patching.  Patch by me; thanks to Hamid Akhtar for review.

Discussion: https://postgr.es/m/16040-eaacad11fecfb198@postgresql.org
This commit is contained in:
Tom Lane 2020-06-12 12:14:32 -04:00
parent aaf8c99050
commit 2f48ede080
9 changed files with 800 additions and 151 deletions
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349
doc/src/sgml/spi.sgml
View File

@ -785,6 +785,133 @@ int SPI_execute_with_args(const char *<parameter>command</parameter>,
<!-- *********************************************** -->
<refentry id="spi-spi-execute-with-receiver">
<indexterm><primary>SPI_execute_with_receiver</primary></indexterm>
<refmeta>
<refentrytitle>SPI_execute_with_receiver</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>SPI_execute_with_receiver</refname>
<refpurpose>execute a command with out-of-line parameters</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
int SPI_execute_with_receiver(const char *<parameter>command</parameter>,
ParamListInfo <parameter>params</parameter>,
bool <parameter>read_only</parameter>,
long <parameter>count</parameter>,
DestReceiver *<parameter>dest</parameter>)
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<function>SPI_execute_with_receiver</function> executes a command that might
include references to externally supplied parameters. The command text
refers to a parameter as <literal>$<replaceable>n</replaceable></literal>,
and the <parameter>params</parameter> object provides values and type
information for each such symbol.
<parameter>read_only</parameter> and <parameter>count</parameter> have
the same interpretation as in <function>SPI_execute</function>.
</para>
<para>
If <parameter>dest</parameter> is not NULL, then result tuples are passed
to that object as they are generated by the executor, instead of being
accumulated in <varname>SPI_tuptable</varname>. Using a
caller-supplied <literal>DestReceiver</literal> object is particularly
helpful for queries that might generate many tuples, since the data can
be processed on-the-fly instead of being accumulated in memory.
</para>
<para>
The <parameter>params</parameter> object should normally mark each
parameter with the <literal>PARAM_FLAG_CONST</literal> flag, since
a one-shot plan is always used for the query.
</para>
</refsect1>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><literal>const char * <parameter>command</parameter></literal></term>
<listitem>
<para>
command string
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
<listitem>
<para>
data structure containing parameter types and values; NULL if none
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>bool <parameter>read_only</parameter></literal></term>
<listitem>
<para><literal>true</literal> for read-only execution</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>long <parameter>count</parameter></literal></term>
<listitem>
<para>
maximum number of rows to return,
or <literal>0</literal> for no limit
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DestReceiver * <parameter>dest</parameter></literal></term>
<listitem>
<para>
<literal>DestReceiver</literal> object that will receive any tuples
emitted by the query; if NULL, tuples are returned
in <varname>SPI_tuptable</varname>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
The return value is the same as for <function>SPI_execute</function>.
</para>
<para>
When <parameter>dest</parameter> is NULL,
<varname>SPI_processed</varname> and
<varname>SPI_tuptable</varname> are set as in
<function>SPI_execute</function>.
When <parameter>dest</parameter> is not NULL,
<varname>SPI_processed</varname> is set to zero and
<varname>SPI_tuptable</varname> is set to NULL. If a tuple count
is required, the caller's <literal>DestReceiver</literal> object must
calculate it.
</para>
</refsect1>
</refentry>
<!-- *********************************************** -->
<refentry id="spi-spi-prepare">
<indexterm><primary>SPI_prepare</primary></indexterm>
@ -1564,6 +1691,120 @@ int SPI_execute_plan_with_paramlist(SPIPlanPtr <parameter>plan</parameter>,
<!-- *********************************************** -->
<refentry id="spi-spi-execute-plan-with-receiver">
<indexterm><primary>SPI_execute_plan_with_receiver</primary></indexterm>
<refmeta>
<refentrytitle>SPI_execute_plan_with_receiver</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>SPI_execute_plan_with_receiver</refname>
<refpurpose>execute a statement prepared by <function>SPI_prepare</function></refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
int SPI_execute_plan_with_receiver(SPIPlanPtr <parameter>plan</parameter>,
ParamListInfo <parameter>params</parameter>,
bool <parameter>read_only</parameter>,
long <parameter>count</parameter>,
DestReceiver *<parameter>dest</parameter>)
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<function>SPI_execute_plan_with_receiver</function> executes a statement
prepared by <function>SPI_prepare</function>. This function is
equivalent to <function>SPI_execute_plan_with_paramlist</function>
except that, instead of always accumulating the result tuples into a
<varname>SPI_tuptable</varname> structure, tuples can be passed to a
caller-supplied <literal>DestReceiver</literal> object as they are
generated by the executor. This is particularly helpful for queries
that might generate many tuples, since the data can be processed
on-the-fly instead of being accumulated in memory.
</para>
</refsect1>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><literal>SPIPlanPtr <parameter>plan</parameter></literal></term>
<listitem>
<para>
prepared statement (returned by <function>SPI_prepare</function>)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
<listitem>
<para>
data structure containing parameter types and values; NULL if none
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>bool <parameter>read_only</parameter></literal></term>
<listitem>
<para><literal>true</literal> for read-only execution</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>long <parameter>count</parameter></literal></term>
<listitem>
<para>
maximum number of rows to return,
or <literal>0</literal> for no limit
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DestReceiver * <parameter>dest</parameter></literal></term>
<listitem>
<para>
<literal>DestReceiver</literal> object that will receive any tuples
emitted by the query; if NULL, this function is exactly equivalent to
<function>SPI_execute_plan_with_paramlist</function>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
The return value is the same as for <function>SPI_execute_plan</function>.
</para>
<para>
When <parameter>dest</parameter> is NULL,
<varname>SPI_processed</varname> and
<varname>SPI_tuptable</varname> are set as in
<function>SPI_execute_plan</function>.
When <parameter>dest</parameter> is not NULL,
<varname>SPI_processed</varname> is set to zero and
<varname>SPI_tuptable</varname> is set to NULL. If a tuple count
is required, the caller's <literal>DestReceiver</literal> object must
calculate it.
</para>
</refsect1>
</refentry>
<!-- *********************************************** -->
<refentry id="spi-spi-execp">
<indexterm><primary>SPI_execp</primary></indexterm>
@ -2041,6 +2282,114 @@ Portal SPI_cursor_open_with_paramlist(const char *<parameter>name</parameter>,
<!-- *********************************************** -->
<refentry id="spi-spi-cursor-parse-open-with-paramlist">
<indexterm><primary>SPI_cursor_parse_open_with_paramlist</primary></indexterm>
<refmeta>
<refentrytitle>SPI_cursor_parse_open_with_paramlist</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>SPI_cursor_parse_open_with_paramlist</refname>
<refpurpose>set up a cursor using a query and parameters</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
Portal SPI_cursor_parse_open_with_paramlist(const char *<parameter>name</parameter>,
const char *<parameter>command</parameter>,
ParamListInfo <parameter>params</parameter>,
bool <parameter>read_only</parameter>,
int <parameter>cursorOptions</parameter>)
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<function>SPI_cursor_parse_open_with_paramlist</function> sets up a cursor
(internally, a portal) that will execute the specified query. This
function is equivalent to <function>SPI_cursor_open_with_args</function>
except that any parameters referenced by the query are provided by
a <literal>ParamListInfo</literal> object, rather than in ad-hoc arrays.
</para>
<para>
The <parameter>params</parameter> object should normally mark each
parameter with the <literal>PARAM_FLAG_CONST</literal> flag, since
a one-shot plan is always used for the query.
</para>
<para>
The passed-in parameter data will be copied into the cursor's portal, so it
can be freed while the cursor still exists.
</para>
</refsect1>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><literal>const char * <parameter>name</parameter></literal></term>
<listitem>
<para>
name for portal, or <symbol>NULL</symbol> to let the system
select a name
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>const char * <parameter>command</parameter></literal></term>
<listitem>
<para>
command string
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ParamListInfo <parameter>params</parameter></literal></term>
<listitem>
<para>
data structure containing parameter types and values; NULL if none
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>bool <parameter>read_only</parameter></literal></term>
<listitem>
<para><literal>true</literal> for read-only execution</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>int <parameter>cursorOptions</parameter></literal></term>
<listitem>
<para>
integer bit mask of cursor options; zero produces default behavior
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
Pointer to portal containing the cursor. Note there is no error
return convention; any error will be reported via <function>elog</function>.
</para>
</refsect1>
</refentry>
<!-- *********************************************** -->
<refentry id="spi-spi-cursor-find">
<indexterm><primary>SPI_cursor_find</primary></indexterm>

4
src/backend/commands/portalcmds.c
View File

@ -383,7 +383,9 @@ PersistHoldablePortal(Portal portal)
SetTuplestoreDestReceiverParams(queryDesc->dest,
portal->holdStore,
portal->holdContext,
true);
true,
NULL,
NULL);
/* Fetch the result set into the tuplestore */
ExecutorRun(queryDesc, ForwardScanDirection, 0L, false);

159
src/backend/executor/spi.c
View File

@ -60,7 +60,8 @@ static void _SPI_prepare_oneshot_plan(const char *src, SPIPlanPtr plan);
static int _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
Snapshot snapshot, Snapshot crosscheck_snapshot,
bool read_only, bool fire_triggers, uint64 tcount);
bool read_only, bool fire_triggers, uint64 tcount,
DestReceiver *caller_dest);
static ParamListInfo _SPI_convert_params(int nargs, Oid *argtypes,
Datum *Values, const char *Nulls);
@ -513,7 +514,7 @@ SPI_execute(const char *src, bool read_only, long tcount)
res = _SPI_execute_plan(&plan, NULL,
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount);
read_only, true, tcount, NULL);
_SPI_end_call(true);
return res;
@ -547,7 +548,7 @@ SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
_SPI_convert_params(plan->nargs, plan->argtypes,
Values, Nulls),
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount);
read_only, true, tcount, NULL);
_SPI_end_call(true);
return res;
@ -576,7 +577,36 @@ SPI_execute_plan_with_paramlist(SPIPlanPtr plan, ParamListInfo params,
res = _SPI_execute_plan(plan, params,
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount);
read_only, true, tcount, NULL);
_SPI_end_call(true);
return res;
}
/*
* Execute a previously prepared plan. If dest isn't NULL, we send result
* tuples to the caller-supplied DestReceiver rather than through the usual
* SPI output arrangements. If dest is NULL this is equivalent to
* SPI_execute_plan_with_paramlist.
*/
int
SPI_execute_plan_with_receiver(SPIPlanPtr plan,
ParamListInfo params,
bool read_only, long tcount,
DestReceiver *dest)
{
int res;
if (plan == NULL || plan->magic != _SPI_PLAN_MAGIC || tcount < 0)
return SPI_ERROR_ARGUMENT;
res = _SPI_begin_call(true);
if (res < 0)
return res;
res = _SPI_execute_plan(plan, params,
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount, dest);
_SPI_end_call(true);
return res;
@ -617,7 +647,7 @@ SPI_execute_snapshot(SPIPlanPtr plan,
_SPI_convert_params(plan->nargs, plan->argtypes,
Values, Nulls),
snapshot, crosscheck_snapshot,
read_only, fire_triggers, tcount);
read_only, fire_triggers, tcount, NULL);
_SPI_end_call(true);
return res;
@ -664,7 +694,50 @@ SPI_execute_with_args(const char *src,
res = _SPI_execute_plan(&plan, paramLI,
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount);
read_only, true, tcount, NULL);
_SPI_end_call(true);
return res;
}
/*
* SPI_execute_with_receiver -- plan and execute a query with arguments
*
* This is the same as SPI_execute_with_args except that parameters are
* supplied through a ParamListInfo, and (if dest isn't NULL) we send
* result tuples to the caller-supplied DestReceiver rather than through
* the usual SPI output arrangements.
*/
int
SPI_execute_with_receiver(const char *src,
ParamListInfo params,
bool read_only, long tcount,
DestReceiver *dest)
{
int res;
_SPI_plan plan;
if (src == NULL || tcount < 0)
return SPI_ERROR_ARGUMENT;
res = _SPI_begin_call(true);
if (res < 0)
return res;
memset(&plan, 0, sizeof(_SPI_plan));
plan.magic = _SPI_PLAN_MAGIC;
plan.cursor_options = CURSOR_OPT_PARALLEL_OK;
if (params)
{
plan.parserSetup = params->parserSetup;
plan.parserSetupArg = params->parserSetupArg;
}
_SPI_prepare_oneshot_plan(src, &plan);
res = _SPI_execute_plan(&plan, params,
InvalidSnapshot, InvalidSnapshot,
read_only, true, tcount, dest);
_SPI_end_call(true);
return res;
@ -1303,6 +1376,49 @@ SPI_cursor_open_with_paramlist(const char *name, SPIPlanPtr plan,
return SPI_cursor_open_internal(name, plan, params, read_only);
}
/*
* SPI_cursor_parse_open_with_paramlist()
*
* Same as SPI_cursor_open_with_args except that parameters (if any) are passed
* as a ParamListInfo, which supports dynamic parameter set determination
*/
Portal
SPI_cursor_parse_open_with_paramlist(const char *name,
const char *src,
ParamListInfo params,
bool read_only, int cursorOptions)
{
Portal result;
_SPI_plan plan;
if (src == NULL)
elog(ERROR, "SPI_cursor_parse_open_with_paramlist called with invalid arguments");
SPI_result = _SPI_begin_call(true);
if (SPI_result < 0)
elog(ERROR, "SPI_cursor_parse_open_with_paramlist called while not connected");
memset(&plan, 0, sizeof(_SPI_plan));
plan.magic = _SPI_PLAN_MAGIC;
plan.cursor_options = cursorOptions;
if (params)
{
plan.parserSetup = params->parserSetup;
plan.parserSetupArg = params->parserSetupArg;
}
_SPI_prepare_plan(src, &plan);
/* We needn't copy the plan; SPI_cursor_open_internal will do so */
result = SPI_cursor_open_internal(name, &plan, params, read_only);
/* And clean up */
_SPI_end_call(true);
return result;
}
/*
* SPI_cursor_open_internal()
@ -2090,11 +2206,13 @@ _SPI_prepare_oneshot_plan(const char *src, SPIPlanPtr plan)
* fire_triggers: true to fire AFTER triggers at end of query (normal case);
* false means any AFTER triggers are postponed to end of outer query
* tcount: execution tuple-count limit, or 0 for none
* caller_dest: DestReceiver to receive output, or NULL for normal SPI output
*/
static int
_SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
Snapshot snapshot, Snapshot crosscheck_snapshot,
bool read_only, bool fire_triggers, uint64 tcount)
bool read_only, bool fire_triggers, uint64 tcount,
DestReceiver *caller_dest)
{
int my_res = 0;
uint64 my_processed = 0;
@ -2228,6 +2346,12 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
bool canSetTag = stmt->canSetTag;
DestReceiver *dest;
/*
* Reset output state. (Note that if a non-SPI receiver is used,
* _SPI_current->processed will stay zero, and that's what we'll
* report to the caller. It's the receiver's job to count tuples
* in that case.)
*/
_SPI_current->processed = 0;
_SPI_current->tuptable = NULL;
@ -2267,7 +2391,16 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
UpdateActiveSnapshotCommandId();
}
dest = CreateDestReceiver(canSetTag ? DestSPI : DestNone);
/*
* Select appropriate tuple receiver. Output from non-canSetTag
* subqueries always goes to the bit bucket.
*/
if (!canSetTag)
dest = CreateDestReceiver(DestNone);
else if (caller_dest)
dest = caller_dest;
else
dest = CreateDestReceiver(DestSPI);
if (stmt->utilityStmt == NULL)
{
@ -2373,7 +2506,13 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
SPI_freetuptable(_SPI_current->tuptable);
_SPI_current->tuptable = NULL;
}
/* we know that the receiver doesn't need a destroy call */
/*
* We don't issue a destroy call to the receiver. The SPI and
* None receivers would ignore it anyway, while if the caller
* supplied a receiver, it's not our job to destroy it.
*/
if (res < 0)
{
my_res = res;
@ -2465,7 +2604,7 @@ _SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount)
switch (operation)
{
case CMD_SELECT:
if (queryDesc->dest->mydest != DestSPI)
if (queryDesc->dest->mydest == DestNone)
{
/* Don't return SPI_OK_SELECT if we're discarding result */
res = SPI_OK_UTILITY;

67
src/backend/executor/tstoreReceiver.c
View File

@ -8,6 +8,8 @@
* toasted values. This is to support cursors WITH HOLD, which must retain
* data even if the underlying table is dropped.
*
* Also optionally, we can apply a tuple conversion map before storing.
*
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
@ -21,6 +23,7 @@
#include "postgres.h"
#include "access/detoast.h"
#include "access/tupconvert.h"
#include "executor/tstoreReceiver.h"
@ -31,14 +34,19 @@ typedef struct
Tuplestorestate *tstore; /* where to put the data */
MemoryContext cxt; /* context containing tstore */
bool detoast; /* were we told to detoast? */
TupleDesc target_tupdesc; /* target tupdesc, or NULL if none */
const char *map_failure_msg; /* tupdesc mapping failure message */
/* workspace: */
Datum *outvalues; /* values array for result tuple */
Datum *tofree; /* temp values to be pfree'd */
TupleConversionMap *tupmap; /* conversion map, if needed */
TupleTableSlot *mapslot; /* slot for mapped tuples */
} TStoreState;
static bool tstoreReceiveSlot_notoast(TupleTableSlot *slot, DestReceiver *self);
static bool tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self);
static bool tstoreReceiveSlot_tupmap(TupleTableSlot *slot, DestReceiver *self);
/*
@ -69,27 +77,46 @@ tstoreStartupReceiver(DestReceiver *self, int operation, TupleDesc typeinfo)
}
}
/* Check if tuple conversion is needed */
if (myState->target_tupdesc)
myState->tupmap = convert_tuples_by_position(typeinfo,
myState->target_tupdesc,
myState->map_failure_msg);
else
myState->tupmap = NULL;
/* Set up appropriate callback */
if (needtoast)
{
Assert(!myState->tupmap);
myState->pub.receiveSlot = tstoreReceiveSlot_detoast;
/* Create workspace */
myState->outvalues = (Datum *)
MemoryContextAlloc(myState->cxt, natts * sizeof(Datum));
myState->tofree = (Datum *)
MemoryContextAlloc(myState->cxt, natts * sizeof(Datum));
myState->mapslot = NULL;
}
else if (myState->tupmap)
{
myState->pub.receiveSlot = tstoreReceiveSlot_tupmap;
myState->outvalues = NULL;
myState->tofree = NULL;
myState->mapslot = MakeSingleTupleTableSlot(myState->target_tupdesc,
&TTSOpsVirtual);
}
else
{
myState->pub.receiveSlot = tstoreReceiveSlot_notoast;
myState->outvalues = NULL;
myState->tofree = NULL;
myState->mapslot = NULL;
}
}
/*
* Receive a tuple from the executor and store it in the tuplestore.
* This is for the easy case where we don't have to detoast.
* This is for the easy case where we don't have to detoast nor map anything.
*/
static bool
tstoreReceiveSlot_notoast(TupleTableSlot *slot, DestReceiver *self)
@ -157,6 +184,21 @@ tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
return true;
}
/*
* Receive a tuple from the executor and store it in the tuplestore.
* This is for the case where we must apply a tuple conversion map.
*/
static bool
tstoreReceiveSlot_tupmap(TupleTableSlot *slot, DestReceiver *self)
{
TStoreState *myState = (TStoreState *) self;
execute_attr_map_slot(myState->tupmap->attrMap, slot, myState->mapslot);
tuplestore_puttupleslot(myState->tstore, myState->mapslot);
return true;
}
/*
* Clean up at end of an executor run
*/
@ -172,6 +214,12 @@ tstoreShutdownReceiver(DestReceiver *self)
if (myState->tofree)
pfree(myState->tofree);
myState->tofree = NULL;
if (myState->tupmap)
free_conversion_map(myState->tupmap);
myState->tupmap = NULL;
if (myState->mapslot)
ExecDropSingleTupleTableSlot(myState->mapslot);
myState->mapslot = NULL;
}
/*
@ -204,17 +252,32 @@ CreateTuplestoreDestReceiver(void)
/*
* Set parameters for a TuplestoreDestReceiver
*
* tStore: where to store the tuples
* tContext: memory context containing tStore
* detoast: forcibly detoast contained data?
* target_tupdesc: if not NULL, forcibly convert tuples to this rowtype
* map_failure_msg: error message to use if mapping to target_tupdesc fails
*
* We don't currently support both detoast and target_tupdesc at the same
* time, just because no existing caller needs that combination.
*/
void
SetTuplestoreDestReceiverParams(DestReceiver *self,
Tuplestorestate *tStore,
MemoryContext tContext,
bool detoast)
bool detoast,
TupleDesc target_tupdesc,
const char *map_failure_msg)
{
TStoreState *myState = (TStoreState *) self;
Assert(!(detoast && target_tupdesc));
Assert(myState->pub.mydest == DestTuplestore);
myState->tstore = tStore;
myState->cxt = tContext;
myState->detoast = detoast;
myState->target_tupdesc = target_tupdesc;
myState->map_failure_msg = map_failure_msg;
}

63
src/backend/nodes/params.c
View File

@ -17,19 +17,27 @@
#include "access/xact.h"
#include "mb/stringinfo_mb.h"
#include "nodes/bitmapset.h"
#include "nodes/params.h"
#include "parser/parse_node.h"
#include "storage/shmem.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
static void paramlist_parser_setup(ParseState *pstate, void *arg);
static Node *paramlist_param_ref(ParseState *pstate, ParamRef *pref);
/*
* Allocate and initialize a new ParamListInfo structure.
*
* To make a new structure for the "dynamic" way (with hooks), pass 0 for
* numParams and set numParams manually.
*
* A default parserSetup function is supplied automatically. Callers may
* override it if they choose. (Note that most use-cases for ParamListInfos
* will never use the parserSetup function anyway.)
*/
ParamListInfo
makeParamList(int numParams)
@ -45,8 +53,8 @@ makeParamList(int numParams)
retval->paramFetchArg = NULL;
retval->paramCompile = NULL;
retval->paramCompileArg = NULL;
retval->parserSetup = NULL;
retval->parserSetupArg = NULL;
retval->parserSetup = paramlist_parser_setup;
retval->parserSetupArg = (void *) retval;
retval->paramValuesStr = NULL;
retval->numParams = numParams;
@ -102,6 +110,55 @@ copyParamList(ParamListInfo from)
return retval;
}
/*
* Set up to parse a query containing references to parameters
* sourced from a ParamListInfo.
*/
static void
paramlist_parser_setup(ParseState *pstate, void *arg)
{
pstate->p_paramref_hook = paramlist_param_ref;
/* no need to use p_coerce_param_hook */
pstate->p_ref_hook_state = arg;
}
/*
* Transform a ParamRef using parameter type data from a ParamListInfo.
*/
static Node *
paramlist_param_ref(ParseState *pstate, ParamRef *pref)
{
ParamListInfo paramLI = (ParamListInfo) pstate->p_ref_hook_state;
int paramno = pref->number;
ParamExternData *prm;
ParamExternData prmdata;
Param *param;
/* check parameter number is valid */
if (paramno <= 0 || paramno > paramLI->numParams)
return NULL;
/* give hook a chance in case parameter is dynamic */
if (paramLI->paramFetch != NULL)
prm = paramLI->paramFetch(paramLI, paramno, false, &prmdata);
else
prm = &paramLI->params[paramno - 1];
if (!OidIsValid(prm->ptype))
return NULL;
param = makeNode(Param);
param->paramkind = PARAM_EXTERN;
param->paramid = paramno;
param->paramtype = prm->ptype;
param->paramtypmod = -1;
param->paramcollid = get_typcollation(param->paramtype);
param->location = pref->location;
return (Node *) param;
}
/*
* Estimate the amount of space required to serialize a ParamListInfo.
*/

4
src/backend/tcop/pquery.c
View File

@ -996,7 +996,9 @@ FillPortalStore(Portal portal, bool isTopLevel)
SetTuplestoreDestReceiverParams(treceiver,
portal->holdStore,
portal->holdContext,
false);
false,
NULL,
NULL);
switch (portal->strategy)
{

13
src/include/executor/spi.h
View File

@ -90,6 +90,10 @@ extern int SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
extern int SPI_execute_plan_with_paramlist(SPIPlanPtr plan,
ParamListInfo params,
bool read_only, long tcount);
extern int SPI_execute_plan_with_receiver(SPIPlanPtr plan,
ParamListInfo params,
bool read_only, long tcount,
DestReceiver *dest);
extern int SPI_exec(const char *src, long tcount);
extern int SPI_execp(SPIPlanPtr plan, Datum *Values, const char *Nulls,
long tcount);
@ -102,6 +106,10 @@ extern int SPI_execute_with_args(const char *src,
int nargs, Oid *argtypes,
Datum *Values, const char *Nulls,
bool read_only, long tcount);
extern int SPI_execute_with_receiver(const char *src,
ParamListInfo params,
bool read_only, long tcount,
DestReceiver *dest);
extern SPIPlanPtr SPI_prepare(const char *src, int nargs, Oid *argtypes);
extern SPIPlanPtr SPI_prepare_cursor(const char *src, int nargs, Oid *argtypes,
int cursorOptions);
@ -150,6 +158,11 @@ extern Portal SPI_cursor_open_with_args(const char *name,
bool read_only, int cursorOptions);
extern Portal SPI_cursor_open_with_paramlist(const char *name, SPIPlanPtr plan,
ParamListInfo params, bool read_only);
extern Portal SPI_cursor_parse_open_with_paramlist(const char *name,
const char *src,
ParamListInfo params,
bool read_only,
int cursorOptions);
extern Portal SPI_cursor_find(const char *name);
extern void SPI_cursor_fetch(Portal portal, bool forward, long count);
extern void SPI_cursor_move(Portal portal, bool forward, long count);

4
src/include/executor/tstoreReceiver.h
View File

@ -24,6 +24,8 @@ extern DestReceiver *CreateTuplestoreDestReceiver(void);
extern void SetTuplestoreDestReceiverParams(DestReceiver *self,
Tuplestorestate *tStore,
MemoryContext tContext,
bool detoast);
bool detoast,
TupleDesc target_tupdesc,
const char *map_failure_msg);
#endif /* TSTORE_RECEIVER_H */

288
src/pl/plpgsql/src/pl_exec.c
View File

@ -27,6 +27,7 @@
#include "executor/execExpr.h"
#include "executor/spi.h"
#include "executor/spi_priv.h"
#include "executor/tstoreReceiver.h"
#include "funcapi.h"
#include "mb/stringinfo_mb.h"
#include "miscadmin.h"
@ -51,14 +52,6 @@
#include "utils/syscache.h"
#include "utils/typcache.h"
typedef struct
{
int nargs; /* number of arguments */
Oid *types; /* types of arguments */
Datum *values; /* evaluated argument values */
char *nulls; /* null markers (' '/'n' style) */
} PreparedParamsData;
/*
* All plpgsql function executions within a single transaction share the same
* executor EState for evaluating "simple" expressions. Each function call
@ -441,15 +434,15 @@ static void assign_text_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
const char *str);
static void assign_record_var(PLpgSQL_execstate *estate, PLpgSQL_rec *rec,
ExpandedRecordHeader *erh);
static PreparedParamsData *exec_eval_using_params(PLpgSQL_execstate *estate,
List *params);
static ParamListInfo exec_eval_using_params(PLpgSQL_execstate *estate,
List *params);
static Portal exec_dynquery_with_params(PLpgSQL_execstate *estate,
PLpgSQL_expr *dynquery, List *params,
const char *portalname, int cursorOptions);
static char *format_expr_params(PLpgSQL_execstate *estate,
const PLpgSQL_expr *expr);
static char *format_preparedparamsdata(PLpgSQL_execstate *estate,
const PreparedParamsData *ppd);
ParamListInfo paramLI);
/* ----------
@ -3513,9 +3506,11 @@ static int
exec_stmt_return_query(PLpgSQL_execstate *estate,
PLpgSQL_stmt_return_query *stmt)
{
Portal portal;
uint64 processed = 0;
TupleConversionMap *tupmap;
int64 tcount;
DestReceiver *treceiver;
int rc;
uint64 processed;
MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
MemoryContext oldcontext;
if (!estate->retisset)
@ -3525,60 +3520,99 @@ exec_stmt_return_query(PLpgSQL_execstate *estate,
if (estate->tuple_store == NULL)
exec_init_tuple_store(estate);
/* There might be some tuples in the tuplestore already */
tcount = tuplestore_tuple_count(estate->tuple_store);
/*
* Set up DestReceiver to transfer results directly to tuplestore,
* converting rowtype if necessary. DestReceiver lives in mcontext.
*/
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
treceiver = CreateDestReceiver(DestTuplestore);
SetTuplestoreDestReceiverParams(treceiver,
estate->tuple_store,
estate->tuple_store_cxt,
false,
estate->tuple_store_desc,
gettext_noop("structure of query does not match function result type"));
MemoryContextSwitchTo(oldcontext);
if (stmt->query != NULL)
{
/* static query */
exec_run_select(estate, stmt->query, 0, &portal);
PLpgSQL_expr *expr = stmt->query;
ParamListInfo paramLI;
/*
* On the first call for this expression generate the plan.
*/
if (expr->plan == NULL)
exec_prepare_plan(estate, expr, CURSOR_OPT_PARALLEL_OK, true);
/*
* Set up ParamListInfo to pass to executor
*/
paramLI = setup_param_list(estate, expr);
/*
* Execute the query
*/
rc = SPI_execute_plan_with_receiver(expr->plan, paramLI,
estate->readonly_func, 0,
treceiver);
if (rc != SPI_OK_SELECT)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("query \"%s\" is not a SELECT", expr->query)));
}
else
{
/* RETURN QUERY EXECUTE */
Datum query;
bool isnull;
Oid restype;
int32 restypmod;
char *querystr;
/*
* Evaluate the string expression after the EXECUTE keyword. Its
* result is the querystring we have to execute.
*/
Assert(stmt->dynquery != NULL);
portal = exec_dynquery_with_params(estate, stmt->dynquery,
stmt->params, NULL,
0);
query = exec_eval_expr(estate, stmt->dynquery,
&isnull, &restype, &restypmod);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("query string argument of EXECUTE is null")));
/* Get the C-String representation */
querystr = convert_value_to_string(estate, query, restype);
/* copy it into the stmt_mcontext before we clean up */
querystr = MemoryContextStrdup(stmt_mcontext, querystr);
exec_eval_cleanup(estate);
/* Execute query, passing params if necessary */
rc = SPI_execute_with_receiver(querystr,
exec_eval_using_params(estate,
stmt->params),
estate->readonly_func,
0,
treceiver);
if (rc < 0)
elog(ERROR, "SPI_execute_with_receiver failed executing query \"%s\": %s",
querystr, SPI_result_code_string(rc));
}
/* Use eval_mcontext for tuple conversion work */
oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
tupmap = convert_tuples_by_position(portal->tupDesc,
estate->tuple_store_desc,
gettext_noop("structure of query does not match function result type"));
while (true)
{
uint64 i;
SPI_cursor_fetch(portal, true, 50);
/* SPI will have changed CurrentMemoryContext */
MemoryContextSwitchTo(get_eval_mcontext(estate));
if (SPI_processed == 0)
break;
for (i = 0; i < SPI_processed; i++)
{
HeapTuple tuple = SPI_tuptable->vals[i];
if (tupmap)
tuple = execute_attr_map_tuple(tuple, tupmap);
tuplestore_puttuple(estate->tuple_store, tuple);
if (tupmap)
heap_freetuple(tuple);
processed++;
}
SPI_freetuptable(SPI_tuptable);
}
SPI_freetuptable(SPI_tuptable);
SPI_cursor_close(portal);
MemoryContextSwitchTo(oldcontext);
/* Clean up */
treceiver->rDestroy(treceiver);
exec_eval_cleanup(estate);
MemoryContextReset(stmt_mcontext);
/* Count how many tuples we got */
processed = tuplestore_tuple_count(estate->tuple_store) - tcount;
estate->eval_processed = processed;
exec_set_found(estate, processed != 0);
@ -4344,7 +4378,7 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
int32 restypmod;
char *querystr;
int exec_res;
PreparedParamsData *ppd = NULL;
ParamListInfo paramLI;
MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
/*
@ -4368,16 +4402,9 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
/*
* Execute the query without preparing a saved plan.
*/
if (stmt->params)
{
ppd = exec_eval_using_params(estate, stmt->params);
exec_res = SPI_execute_with_args(querystr,
ppd->nargs, ppd->types,
ppd->values, ppd->nulls,
estate->readonly_func, 0);
}
else
exec_res = SPI_execute(querystr, estate->readonly_func, 0);
paramLI = exec_eval_using_params(estate, stmt->params);
exec_res = SPI_execute_with_receiver(querystr, paramLI,
estate->readonly_func, 0, NULL);
switch (exec_res)
{
@ -4429,7 +4456,7 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
break;
default:
elog(ERROR, "SPI_execute failed executing query \"%s\": %s",
elog(ERROR, "SPI_execute_with_receiver failed executing query \"%s\": %s",
querystr, SPI_result_code_string(exec_res));
break;
}
@ -4465,7 +4492,7 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
char *errdetail;
if (estate->func->print_strict_params)
errdetail = format_preparedparamsdata(estate, ppd);
errdetail = format_preparedparamsdata(estate, paramLI);
else
errdetail = NULL;
@ -4484,7 +4511,7 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
char *errdetail;
if (estate->func->print_strict_params)
errdetail = format_preparedparamsdata(estate, ppd);
errdetail = format_preparedparamsdata(estate, paramLI);
else
errdetail = NULL;
@ -6308,9 +6335,9 @@ exec_eval_simple_expr(PLpgSQL_execstate *estate,
/*
* Create a ParamListInfo to pass to SPI
*
* We use a single ParamListInfo struct for all SPI calls made from this
* estate; it contains no per-param data, just hook functions, so it's
* effectively read-only for SPI.
* We use a single ParamListInfo struct for all SPI calls made to evaluate
* PLpgSQL_exprs in this estate. It contains no per-param data, just hook
* functions, so it's effectively read-only for SPI.
*
* An exception from pure read-only-ness is that the parserSetupArg points
* to the specific PLpgSQL_expr being evaluated. This is not an issue for
@ -8575,65 +8602,68 @@ assign_record_var(PLpgSQL_execstate *estate, PLpgSQL_rec *rec,
* The result data structure is created in the stmt_mcontext, and should
* be freed by resetting that context.
*/
static PreparedParamsData *
static ParamListInfo
exec_eval_using_params(PLpgSQL_execstate *estate, List *params)
{
PreparedParamsData *ppd;
MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
ParamListInfo paramLI;
int nargs;
MemoryContext stmt_mcontext;
MemoryContext oldcontext;
int i;
ListCell *lc;
ppd = (PreparedParamsData *)
MemoryContextAlloc(stmt_mcontext, sizeof(PreparedParamsData));
nargs = list_length(params);
/* Fast path for no parameters: we can just return NULL */
if (params == NIL)
return NULL;
ppd->nargs = nargs;
ppd->types = (Oid *)
MemoryContextAlloc(stmt_mcontext, nargs * sizeof(Oid));
ppd->values = (Datum *)
MemoryContextAlloc(stmt_mcontext, nargs * sizeof(Datum));
ppd->nulls = (char *)
MemoryContextAlloc(stmt_mcontext, nargs * sizeof(char));
nargs = list_length(params);
stmt_mcontext = get_stmt_mcontext(estate);
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
paramLI = makeParamList(nargs);
MemoryContextSwitchTo(oldcontext);
i = 0;
foreach(lc, params)
{
PLpgSQL_expr *param = (PLpgSQL_expr *) lfirst(lc);
bool isnull;
ParamExternData *prm = &paramLI->params[i];
int32 ppdtypmod;
MemoryContext oldcontext;
ppd->values[i] = exec_eval_expr(estate, param,
&isnull,
&ppd->types[i],
&ppdtypmod);
ppd->nulls[i] = isnull ? 'n' : ' ';
/*
* Always mark params as const, since we only use the result with
* one-shot plans.
*/
prm->pflags = PARAM_FLAG_CONST;
prm->value = exec_eval_expr(estate, param,
&prm->isnull,
&prm->ptype,
&ppdtypmod);
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
if (ppd->types[i] == UNKNOWNOID)
if (prm->ptype == UNKNOWNOID)
{
/*
* Treat 'unknown' parameters as text, since that's what most
* people would expect. SPI_execute_with_args can coerce unknown
* people would expect. The SPI functions can coerce unknown
* constants in a more intelligent way, but not unknown Params.
* This code also takes care of copying into the right context.
* Note we assume 'unknown' has the representation of C-string.
*/
ppd->types[i] = TEXTOID;
if (!isnull)
ppd->values[i] = CStringGetTextDatum(DatumGetCString(ppd->values[i]));
prm->ptype = TEXTOID;
if (!prm->isnull)
prm->value = CStringGetTextDatum(DatumGetCString(prm->value));
}
/* pass-by-ref non null values must be copied into stmt_mcontext */
else if (!isnull)
else if (!prm->isnull)
{
int16 typLen;
bool typByVal;
get_typlenbyval(ppd->types[i], &typLen, &typByVal);
get_typlenbyval(prm->ptype, &typLen, &typByVal);
if (!typByVal)
ppd->values[i] = datumCopy(ppd->values[i], typByVal, typLen);
prm->value = datumCopy(prm->value, typByVal, typLen);
}
MemoryContextSwitchTo(oldcontext);
@ -8643,7 +8673,7 @@ exec_eval_using_params(PLpgSQL_execstate *estate, List *params)
i++;
}
return ppd;
return paramLI;
}
/*
@ -8689,30 +8719,15 @@ exec_dynquery_with_params(PLpgSQL_execstate *estate,
/*
* Open an implicit cursor for the query. We use
* SPI_cursor_open_with_args even when there are no params, because this
* avoids making and freeing one copy of the plan.
* SPI_cursor_parse_open_with_paramlist even when there are no params,
* because this avoids making and freeing one copy of the plan.
*/
if (params)
{
PreparedParamsData *ppd;
ppd = exec_eval_using_params(estate, params);
portal = SPI_cursor_open_with_args(portalname,
querystr,
ppd->nargs, ppd->types,
ppd->values, ppd->nulls,
estate->readonly_func,
cursorOptions);
}
else
{
portal = SPI_cursor_open_with_args(portalname,
querystr,
0, NULL,
NULL, NULL,
estate->readonly_func,
cursorOptions);
}
portal = SPI_cursor_parse_open_with_paramlist(portalname,
querystr,
exec_eval_using_params(estate,
params),
estate->readonly_func,
cursorOptions);
if (portal == NULL)
elog(ERROR, "could not open implicit cursor for query \"%s\": %s",
@ -8782,37 +8797,44 @@ format_expr_params(PLpgSQL_execstate *estate,
}
/*
* Return a formatted string with information about PreparedParamsData, or NULL
* if there are no parameters.
* Return a formatted string with information about the parameter values,
* or NULL if there are no parameters.
* The result is in the eval_mcontext.
*/
static char *
format_preparedparamsdata(PLpgSQL_execstate *estate,
const PreparedParamsData *ppd)
ParamListInfo paramLI)
{
int paramno;
StringInfoData paramstr;
MemoryContext oldcontext;
if (!ppd)
if (!paramLI)
return NULL;
oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
initStringInfo(&paramstr);
for (paramno = 0; paramno < ppd->nargs; paramno++)
for (paramno = 0; paramno < paramLI->numParams; paramno++)
{
ParamExternData *prm = &paramLI->params[paramno];
/*
* Note: for now, this is only used on ParamListInfos produced by
* exec_eval_using_params(), so we don't worry about invoking the
* paramFetch hook or skipping unused parameters.
*/
appendStringInfo(&paramstr, "%s$%d = ",
paramno > 0 ? ", " : "",
paramno + 1);
if (ppd->nulls[paramno] == 'n')
if (prm->isnull)
appendStringInfoString(&paramstr, "NULL");
else
appendStringInfoStringQuoted(&paramstr,
convert_value_to_string(estate,
ppd->values[paramno],
ppd->types[paramno]),
prm->value,
prm->ptype),
-1);
}