281 lines
6.4 KiB
C
281 lines
6.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* dest.c
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* support for communication destinations
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*
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/backend/tcop/dest.c
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* INTERFACE ROUTINES
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* BeginCommand - initialize the destination at start of command
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* CreateDestReceiver - create tuple receiver object for destination
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* EndCommand - clean up the destination at end of command
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* NullCommand - tell dest that an empty query string was recognized
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* ReadyForQuery - tell dest that we are ready for a new query
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*
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* NOTES
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* These routines do the appropriate work before and after
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* tuples are returned by a query to keep the backend and the
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* "destination" portals synchronized.
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*/
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#include "postgres.h"
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#include "access/printsimple.h"
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#include "access/printtup.h"
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#include "access/xact.h"
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#include "commands/copy.h"
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#include "commands/createas.h"
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#include "commands/matview.h"
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#include "executor/functions.h"
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#include "executor/tqueue.h"
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#include "executor/tstoreReceiver.h"
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#include "libpq/libpq.h"
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#include "libpq/pqformat.h"
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#include "utils/portal.h"
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/* ----------------
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* dummy DestReceiver functions
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* ----------------
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*/
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static bool
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donothingReceive(TupleTableSlot *slot, DestReceiver *self)
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{
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return true;
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}
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static void
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donothingStartup(DestReceiver *self, int operation, TupleDesc typeinfo)
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{
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}
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static void
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donothingCleanup(DestReceiver *self)
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{
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/* this is used for both shutdown and destroy methods */
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}
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/* ----------------
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* static DestReceiver structs for dest types needing no local state
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* ----------------
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*/
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static const DestReceiver donothingDR = {
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donothingReceive, donothingStartup, donothingCleanup, donothingCleanup,
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DestNone
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};
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static const DestReceiver debugtupDR = {
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debugtup, debugStartup, donothingCleanup, donothingCleanup,
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DestDebug
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};
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static const DestReceiver printsimpleDR = {
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printsimple, printsimple_startup, donothingCleanup, donothingCleanup,
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DestRemoteSimple
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};
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static const DestReceiver spi_printtupDR = {
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spi_printtup, spi_dest_startup, donothingCleanup, donothingCleanup,
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DestSPI
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};
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/*
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* Globally available receiver for DestNone.
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*
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* It's ok to cast the constness away as any modification of the none receiver
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* would be a bug (which gets easier to catch this way).
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*/
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DestReceiver *None_Receiver = (DestReceiver *) &donothingDR;
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/* ----------------
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* BeginCommand - initialize the destination at start of command
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* ----------------
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*/
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void
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BeginCommand(CommandTag commandTag, CommandDest dest)
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{
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/* Nothing to do at present */
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}
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/* ----------------
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* CreateDestReceiver - return appropriate receiver function set for dest
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* ----------------
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*/
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DestReceiver *
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CreateDestReceiver(CommandDest dest)
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{
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/*
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* It's ok to cast the constness away as any modification of the none
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* receiver would be a bug (which gets easier to catch this way).
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*/
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switch (dest)
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{
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case DestRemote:
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case DestRemoteExecute:
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return printtup_create_DR(dest);
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case DestRemoteSimple:
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return unconstify(DestReceiver *, &printsimpleDR);
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case DestNone:
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return unconstify(DestReceiver *, &donothingDR);
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case DestDebug:
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return unconstify(DestReceiver *, &debugtupDR);
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case DestSPI:
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return unconstify(DestReceiver *, &spi_printtupDR);
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case DestTuplestore:
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return CreateTuplestoreDestReceiver();
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case DestIntoRel:
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return CreateIntoRelDestReceiver(NULL);
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case DestCopyOut:
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return CreateCopyDestReceiver();
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case DestSQLFunction:
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return CreateSQLFunctionDestReceiver();
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case DestTransientRel:
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return CreateTransientRelDestReceiver(InvalidOid);
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case DestTupleQueue:
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return CreateTupleQueueDestReceiver(NULL);
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}
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/* should never get here */
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pg_unreachable();
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}
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/* ----------------
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* EndCommand - clean up the destination at end of command
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* ----------------
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*/
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void
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EndCommand(const QueryCompletion *qc, CommandDest dest, bool force_undecorated_output)
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{
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char completionTag[COMPLETION_TAG_BUFSIZE];
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Size len;
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switch (dest)
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{
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case DestRemote:
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case DestRemoteExecute:
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case DestRemoteSimple:
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len = BuildQueryCompletionString(completionTag, qc,
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force_undecorated_output);
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pq_putmessage('C', completionTag, len + 1);
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case DestNone:
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case DestDebug:
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case DestSPI:
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case DestTuplestore:
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case DestIntoRel:
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case DestCopyOut:
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case DestSQLFunction:
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case DestTransientRel:
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case DestTupleQueue:
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break;
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}
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}
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/* ----------------
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* EndReplicationCommand - stripped down version of EndCommand
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*
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* For use by replication commands.
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* ----------------
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*/
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void
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EndReplicationCommand(const char *commandTag)
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{
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pq_putmessage('C', commandTag, strlen(commandTag) + 1);
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}
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/* ----------------
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* NullCommand - tell dest that an empty query string was recognized
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*
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* This ensures that there will be a recognizable end to the response
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* to an Execute message in the extended query protocol.
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* ----------------
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*/
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void
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NullCommand(CommandDest dest)
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{
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switch (dest)
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{
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case DestRemote:
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case DestRemoteExecute:
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case DestRemoteSimple:
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/* Tell the FE that we saw an empty query string */
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pq_putemptymessage('I');
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break;
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case DestNone:
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case DestDebug:
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case DestSPI:
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case DestTuplestore:
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case DestIntoRel:
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case DestCopyOut:
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case DestSQLFunction:
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case DestTransientRel:
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case DestTupleQueue:
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break;
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}
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}
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/* ----------------
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* ReadyForQuery - tell dest that we are ready for a new query
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*
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* The ReadyForQuery message is sent so that the FE can tell when
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* we are done processing a query string.
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* In versions 3.0 and up, it also carries a transaction state indicator.
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*
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* Note that by flushing the stdio buffer here, we can avoid doing it
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* most other places and thus reduce the number of separate packets sent.
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* ----------------
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*/
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void
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ReadyForQuery(CommandDest dest)
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{
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switch (dest)
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{
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case DestRemote:
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case DestRemoteExecute:
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case DestRemoteSimple:
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{
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StringInfoData buf;
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pq_beginmessage(&buf, 'Z');
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pq_sendbyte(&buf, TransactionBlockStatusCode());
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pq_endmessage(&buf);
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}
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/* Flush output at end of cycle in any case. */
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pq_flush();
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break;
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case DestNone:
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case DestDebug:
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case DestSPI:
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case DestTuplestore:
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case DestIntoRel:
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case DestCopyOut:
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case DestSQLFunction:
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case DestTransientRel:
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case DestTupleQueue:
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break;
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}
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}
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