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Restructure command destination handling so that we pass around

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DestReceiver pointers instead of just CommandDest values.  The DestReceiver
is made at the point where the destination is selected, rather than
deep inside the executor.  This cleans up the original kluge implementation
of tstoreReceiver.c, and makes it easy to support retrieving results
from utility statements inside portals.  Thus, you can now do fun things
like Bind and Execute a FETCH or EXPLAIN command, and it'll all work
as expected (e.g., you can Describe the portal, or use Execute's count
parameter to suspend the output partway through).  Implementation involves
stuffing the utility command's output into a Tuplestore, which would be
kind of annoying for huge output sets, but should be quite acceptable
for typical uses of utility commands.
This commit is contained in:
Tom Lane
2003-05-06 20:26:28 +00:00
parent 299fbb4b37
commit 79913910d4
28 changed files with 698 additions and 349 deletions
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43
src/backend/tcop/dest.c
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@@ -8,14 +8,14 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/tcop/dest.c,v 1.56 2003/05/06 00:20:33 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/tcop/dest.c,v 1.57 2003/05/06 20:26:27 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* BeginCommand - initialize the destination at start of command
* DestToFunction - identify per-tuple processing routines
* CreateDestReceiver - create tuple receiver object for destination
* EndCommand - clean up the destination at end of command
* NullCommand - tell dest that an empty query string was recognized
* ReadyForQuery - tell dest that we are ready for a new query
@@ -30,7 +30,6 @@
#include "access/printtup.h"
#include "access/xact.h"
#include "executor/tstoreReceiver.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
@@ -45,14 +44,15 @@ donothingReceive(HeapTuple tuple, TupleDesc typeinfo, DestReceiver *self)
}
static void
donothingSetup(DestReceiver *self, int operation,
const char *portalName, TupleDesc typeinfo, List *targetlist)
donothingStartup(DestReceiver *self, int operation,
const char *portalName, TupleDesc typeinfo, List *targetlist)
{
}
static void
donothingCleanup(DestReceiver *self)
{
/* this is used for both shutdown and destroy methods */
}
/* ----------------
@@ -60,17 +60,24 @@ donothingCleanup(DestReceiver *self)
* ----------------
*/
static DestReceiver donothingDR = {
donothingReceive, donothingSetup, donothingCleanup
donothingReceive, donothingStartup, donothingCleanup, donothingCleanup,
None
};
static DestReceiver debugtupDR = {
debugtup, debugSetup, donothingCleanup
debugtup, debugStartup, donothingCleanup, donothingCleanup,
Debug
};
static DestReceiver spi_printtupDR = {
spi_printtup, spi_dest_setup, donothingCleanup
spi_printtup, spi_dest_startup, donothingCleanup, donothingCleanup,
SPI
};
/* Globally available receiver for None */
DestReceiver *None_Receiver = &donothingDR;
/* ----------------
* BeginCommand - initialize the destination at start of command
* ----------------
@@ -82,26 +89,19 @@ BeginCommand(const char *commandTag, CommandDest dest)
}
/* ----------------
* DestToFunction - return appropriate receiver function set for dest
* CreateDestReceiver - return appropriate receiver function set for dest
* ----------------
*/
DestReceiver *
DestToFunction(CommandDest dest)
CreateDestReceiver(CommandDest dest)
{
switch (dest)
{
case Remote:
return printtup_create_DR(false, true);
case RemoteInternal:
return printtup_create_DR(true, true);
case RemoteExecute:
/* like Remote, but suppress output of T message */
return printtup_create_DR(false, false);
case RemoteExecuteInternal:
return printtup_create_DR(true, false);
return printtup_create_DR(dest);
case None:
return &donothingDR;
@@ -113,7 +113,12 @@ DestToFunction(CommandDest dest)
return &spi_printtupDR;
case Tuplestore:
return tstoreReceiverCreateDR();
/*
* This is disallowed, you must use tstoreReceiver.c's
* specialized function to create a Tuplestore DestReceiver
*/
elog(ERROR, "CreateDestReceiver: cannot handle Tuplestore");
break;
}
/* should never get here */