/src/backend/tcop/postgres.c

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/*-------------------------------------------------------------------------
 *
 * postgres.c
 *	  POSTGRES C Backend Interface
 *
 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/tcop/postgres.c
 *
 * NOTES
 *	  this is the "main" module of the postgres backend and
 *	  hence the main module of the "traffic cop".
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/time.h>
#include <sys/resource.h>
#endif

#ifndef HAVE_GETRUSAGE
#include "rusagestub.h"
#endif

#include "access/printtup.h"
#include "access/xact.h"
#include "catalog/pg_type.h"
#include "commands/async.h"
#include "commands/prepare.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "nodes/print.h"
#include "optimizer/planner.h"
#include "pgstat.h"
#include "pg_trace.h"
#include "parser/analyze.h"
#include "parser/parser.h"
#include "pg_getopt.h"
#include "postmaster/autovacuum.h"
#include "postmaster/postmaster.h"
#include "replication/slot.h"
#include "replication/walsender.h"
#include "rewrite/rewriteHandler.h"
#include "storage/bufmgr.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "storage/sinval.h"
#include "tcop/fastpath.h"
#include "tcop/pquery.h"
#include "tcop/tcopprot.h"
#include "tcop/utility.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/snapmgr.h"
#include "utils/timeout.h"
#include "utils/timestamp.h"
#include "mb/pg_wchar.h"


/* ----------------
 *		global variables
 * ----------------
 */
const char *debug_query_string; /* client-supplied query string */

/* Note: whereToSendOutput is initialized for the bootstrap/standalone case */
CommandDest whereToSendOutput = DestDebug;

/* flag for logging end of session */
bool		Log_disconnections = false;

int			log_statement = LOGSTMT_NONE;

/* GUC variable for maximum stack depth (measured in kilobytes) */
int			max_stack_depth = 100;

/* wait N seconds to allow attach from a debugger */
int			PostAuthDelay = 0;



/* ----------------
 *		private variables
 * ----------------
 */

/* max_stack_depth converted to bytes for speed of checking */
static long max_stack_depth_bytes = 100 * 1024L;

/*
 * Stack base pointer -- initialized by PostmasterMain and inherited by
 * subprocesses. This is not static because old versions of PL/Java modify
 * it directly. Newer versions use set_stack_base(), but we want to stay
 * binary-compatible for the time being.
 */
char	   *stack_base_ptr = NULL;

/*
 * On IA64 we also have to remember the register stack base.
 */
#if defined(__ia64__) || defined(__ia64)
char	   *register_stack_base_ptr = NULL;
#endif

/*
 * Flag to mark SIGHUP. Whenever the main loop comes around it
 * will reread the configuration file. (Better than doing the
 * reading in the signal handler, ey?)
 */
static volatile sig_atomic_t got_SIGHUP = false;

/*
 * Flag to keep track of whether we have started a transaction.
 * For extended query protocol this has to be remembered across messages.
 */
static bool xact_started = false;

/*
 * Flag to indicate that we are doing the outer loop's read-from-client,
 * as opposed to any random read from client that might happen within
 * commands like COPY FROM STDIN.
 */
static bool DoingCommandRead = false;

/*
 * Flags to implement skip-till-Sync-after-error behavior for messages of
 * the extended query protocol.
 */
static bool doing_extended_query_message = false;
static bool ignore_till_sync = false;

/*
 * If an unnamed prepared statement exists, it's stored here.
 * We keep it separate from the hashtable kept by commands/prepare.c
 * in order to reduce overhead for short-lived queries.
 */
static CachedPlanSource *unnamed_stmt_psrc = NULL;

/* assorted command-line switches */
static const char *userDoption = NULL;	/* -D switch */

static bool EchoQuery = false;	/* -E switch */

/*
 * people who want to use EOF should #define DONTUSENEWLINE in
 * tcop/tcopdebug.h
 */
#ifndef TCOP_DONTUSENEWLINE
static int	UseNewLine = 1;		/* Use newlines query delimiters (the default) */
#else
static int	UseNewLine = 0;		/* Use EOF as query delimiters */
#endif   /* TCOP_DONTUSENEWLINE */

/* whether or not, and why, we were canceled by conflict with recovery */
static bool RecoveryConflictPending = false;
static bool RecoveryConflictRetryable = true;
static ProcSignalReason RecoveryConflictReason;

/* ----------------------------------------------------------------
 *		decls for routines only used in this file
 * ----------------------------------------------------------------
 */
static int	InteractiveBackend(StringInfo inBuf);
static int	interactive_getc(void);
static int	SocketBackend(StringInfo inBuf);
static int	ReadCommand(StringInfo inBuf);
static void forbidden_in_wal_sender(char firstchar);
static List *pg_rewrite_query(Query *query);
static bool check_log_statement(List *stmt_list);
static int	errdetail_execute(List *raw_parsetree_list);
static int	errdetail_params(ParamListInfo params);
static int	errdetail_abort(void);
static int	errdetail_recovery_conflict(void);
static void start_xact_command(void);
static void finish_xact_command(void);
static bool IsTransactionExitStmt(Node *parsetree);
static bool IsTransactionExitStmtList(List *parseTrees);
static bool IsTransactionStmtList(List *parseTrees);
static void drop_unnamed_stmt(void);
static void SigHupHandler(SIGNAL_ARGS);
static void log_disconnections(int code, Datum arg);


/* ----------------------------------------------------------------
 *		routines to obtain user input
 * ----------------------------------------------------------------
 */

/* ----------------
 *	InteractiveBackend() is called for user interactive connections
 *
 *	the string entered by the user is placed in its parameter inBuf,
 *	and we act like a Q message was received.
 *
 *	EOF is returned if end-of-file input is seen; time to shut down.
 * ----------------
 */

static int
InteractiveBackend(StringInfo inBuf)
{
	int			c;				/* character read from getc() */
	bool		end = false;	/* end-of-input flag */
	bool		backslashSeen = false;	/* have we seen a \ ? */

	/*
	 * display a prompt and obtain input from the user
	 */
	printf("backend> ");
	fflush(stdout);

	resetStringInfo(inBuf);

	if (UseNewLine)
	{
		/*
		 * if we are using \n as a delimiter, then read characters until the
		 * \n.
		 */
		while ((c = interactive_getc()) != EOF)
		{
			if (c == '\n')
			{
				if (backslashSeen)
				{
					/* discard backslash from inBuf */
					inBuf->data[--inBuf->len] = '\0';
					backslashSeen = false;
					continue;
				}
				else
				{
					/* keep the newline character */
					appendStringInfoChar(inBuf, '\n');
					break;
				}
			}
			else if (c == '\\')
				backslashSeen = true;
			else
				backslashSeen = false;

			appendStringInfoChar(inBuf, (char) c);
		}

		if (c == EOF)
			end = true;
	}
	else
	{
		/*
		 * otherwise read characters until EOF.
		 */
		while ((c = interactive_getc()) != EOF)
			appendStringInfoChar(inBuf, (char) c);

		/* No input before EOF signal means time to quit. */
		if (inBuf->len == 0)
			end = true;
	}

	if (end)
		return EOF;

	/*
	 * otherwise we have a user query so process it.
	 */

	/* Add '\0' to make it look the same as message case. */
	appendStringInfoChar(inBuf, (char) '\0');

	/*
	 * if the query echo flag was given, print the query..
	 */
	if (EchoQuery)
		printf("statement: %s\n", inBuf->data);
	fflush(stdout);

	return 'Q';
}

/*
 * interactive_getc -- collect one character from stdin
 *
 * Even though we are not reading from a "client" process, we still want to
 * respond to signals, particularly SIGTERM/SIGQUIT.  Hence we must use
 * prepare_for_client_read and client_read_ended.
 */
static int
interactive_getc(void)
{
	int			c;

	prepare_for_client_read();
	c = getc(stdin);
	client_read_ended();
	return c;
}

/* ----------------
 *	SocketBackend()		Is called for frontend-backend connections
 *
 *	Returns the message type code, and loads message body data into inBuf.
 *
 *	EOF is returned if the connection is lost.
 * ----------------
 */
static int
SocketBackend(StringInfo inBuf)
{
	int			qtype;

	/*
	 * Get message type code from the frontend.
	 */
	qtype = pq_getbyte();

	if (qtype == EOF)			/* frontend disconnected */
	{
		if (IsTransactionState())
			ereport(COMMERROR,
					(errcode(ERRCODE_CONNECTION_FAILURE),
					 errmsg("unexpected EOF on client connection with an open transaction")));
		else
		{
			/*
			 * Can't send DEBUG log messages to client at this point. Since
			 * we're disconnecting right away, we don't need to restore
			 * whereToSendOutput.
			 */
			whereToSendOutput = DestNone;
			ereport(DEBUG1,
					(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
					 errmsg("unexpected EOF on client connection")));
		}
		return qtype;
	}

	/*
	 * Validate message type code before trying to read body; if we have lost
	 * sync, better to say "command unknown" than to run out of memory because
	 * we used garbage as a length word.
	 *
	 * This also gives us a place to set the doing_extended_query_message flag
	 * as soon as possible.
	 */
	switch (qtype)
	{
		case 'Q':				/* simple query */
			doing_extended_query_message = false;
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
			{
				/* old style without length word; convert */
				if (pq_getstring(inBuf))
				{
					if (IsTransactionState())
						ereport(COMMERROR,
								(errcode(ERRCODE_CONNECTION_FAILURE),
								 errmsg("unexpected EOF on client connection with an open transaction")));
					else
					{
						/*
						 * Can't send DEBUG log messages to client at this
						 * point.Since we're disconnecting right away, we
						 * don't need to restore whereToSendOutput.
						 */
						whereToSendOutput = DestNone;
						ereport(DEBUG1,
								(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
							 errmsg("unexpected EOF on client connection")));
					}
					return EOF;
				}
			}
			break;

		case 'F':				/* fastpath function call */
			/* we let fastpath.c cope with old-style input of this */
			doing_extended_query_message = false;
			break;

		case 'X':				/* terminate */
			doing_extended_query_message = false;
			ignore_till_sync = false;
			break;

		case 'B':				/* bind */
		case 'C':				/* close */
		case 'D':				/* describe */
		case 'E':				/* execute */
		case 'H':				/* flush */
		case 'P':				/* parse */
			doing_extended_query_message = true;
			/* these are only legal in protocol 3 */
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
				ereport(FATAL,
						(errcode(ERRCODE_PROTOCOL_VIOLATION),
						 errmsg("invalid frontend message type %d", qtype)));
			break;

		case 'S':				/* sync */
			/* stop any active skip-till-Sync */
			ignore_till_sync = false;
			/* mark not-extended, so that a new error doesn't begin skip */
			doing_extended_query_message = false;
			/* only legal in protocol 3 */
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
				ereport(FATAL,
						(errcode(ERRCODE_PROTOCOL_VIOLATION),
						 errmsg("invalid frontend message type %d", qtype)));
			break;

		case 'd':				/* copy data */
		case 'c':				/* copy done */
		case 'f':				/* copy fail */
			doing_extended_query_message = false;
			/* these are only legal in protocol 3 */
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
				ereport(FATAL,
						(errcode(ERRCODE_PROTOCOL_VIOLATION),
						 errmsg("invalid frontend message type %d", qtype)));
			break;

		default:

			/*
			 * Otherwise we got garbage from the frontend.  We treat this as
			 * fatal because we have probably lost message boundary sync, and
			 * there's no good way to recover.
			 */
			ereport(FATAL,
					(errcode(ERRCODE_PROTOCOL_VIOLATION),
					 errmsg("invalid frontend message type %d", qtype)));
			break;
	}

	/*
	 * In protocol version 3, all frontend messages have a length word next
	 * after the type code; we can read the message contents independently of
	 * the type.
	 */
	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
	{
		if (pq_getmessage(inBuf, 0))
			return EOF;			/* suitable message already logged */
	}

	return qtype;
}

/* ----------------
 *		ReadCommand reads a command from either the frontend or
 *		standard input, places it in inBuf, and returns the
 *		message type code (first byte of the message).
 *		EOF is returned if end of file.
 * ----------------
 */
static int
ReadCommand(StringInfo inBuf)
{
	int			result;

	if (whereToSendOutput == DestRemote)
		result = SocketBackend(inBuf);
	else
		result = InteractiveBackend(inBuf);
	return result;
}

/*
 * prepare_for_client_read -- set up to possibly block on client input
 *
 * This must be called immediately before any low-level read from the
 * client connection.  It is necessary to do it at a sufficiently low level
 * that there won't be any other operations except the read kernel call
 * itself between this call and the subsequent client_read_ended() call.
 * In particular there mustn't be use of malloc() or other potentially
 * non-reentrant libc functions.  This restriction makes it safe for us
 * to allow interrupt service routines to execute nontrivial code while
 * we are waiting for input.
 */
void
prepare_for_client_read(void)
{
	if (DoingCommandRead)
	{
		/* Enable immediate processing of asynchronous signals */
		EnableNotifyInterrupt();
		EnableCatchupInterrupt();

		/* Allow cancel/die interrupts to be processed while waiting */
		ImmediateInterruptOK = true;

		/* And don't forget to detect one that already arrived */
		CHECK_FOR_INTERRUPTS();
	}
}

/*
 * client_read_ended -- get out of the client-input state
 *
 * This is called just after low-level reads.  It must preserve errno!
 */
void
client_read_ended(void)
{
	if (DoingCommandRead)
	{
		int			save_errno = errno;

		ImmediateInterruptOK = false;

		DisableNotifyInterrupt();
		DisableCatchupInterrupt();

		errno = save_errno;
	}
}


/*
 * Do raw parsing (only).
 *
 * A list of parsetrees is returned, since there might be multiple
 * commands in the given string.
 *
 * NOTE: for interactive queries, it is important to keep this routine
 * separate from the analysis & rewrite stages.  Analysis and rewriting
 * cannot be done in an aborted transaction, since they require access to
 * database tables.  So, we rely on the raw parser to determine whether
 * we've seen a COMMIT or ABORT command; when we are in abort state, other
 * commands are not processed any further than the raw parse stage.
 */
List *
pg_parse_query(const char *query_string)
{
	List	   *raw_parsetree_list;

	TRACE_POSTGRESQL_QUERY_PARSE_START(query_string);

	if (log_parser_stats)
		ResetUsage();

	raw_parsetree_list = raw_parser(query_string);

	if (log_parser_stats)
		ShowUsage("PARSER STATISTICS");

#ifdef COPY_PARSE_PLAN_TREES
	/* Optional debugging check: pass raw parsetrees through copyObject() */
	{
		List	   *new_list = (List *) copyObject(raw_parsetree_list);

		/* This checks both copyObject() and the equal() routines... */
		if (!equal(new_list, raw_parsetree_list))
			elog(WARNING, "copyObject() failed to produce an equal raw parse tree");
		else
			raw_parsetree_list = new_list;
	}
#endif

	TRACE_POSTGRESQL_QUERY_PARSE_DONE(query_string);

	return raw_parsetree_list;
}

/*
 * Given a raw parsetree (gram.y output), and optionally information about
 * types of parameter symbols ($n), perform parse analysis and rule rewriting.
 *
 * A list of Query nodes is returned, since either the analyzer or the
 * rewriter might expand one query to several.
 *
 * NOTE: for reasons mentioned above, this must be separate from raw parsing.
 */
List *
pg_analyze_and_rewrite(Node *parsetree, const char *query_string,
					   Oid *paramTypes, int numParams)
{
	Query	   *query;
	List	   *querytree_list;

	TRACE_POSTGRESQL_QUERY_REWRITE_START(query_string);

	/*
	 * (1) Perform parse analysis.
	 */
	if (log_parser_stats)
		ResetUsage();

	query = parse_analyze(parsetree, query_string, paramTypes, numParams);

	if (log_parser_stats)
		ShowUsage("PARSE ANALYSIS STATISTICS");

	/*
	 * (2) Rewrite the queries, as necessary
	 */
	querytree_list = pg_rewrite_query(query);

	TRACE_POSTGRESQL_QUERY_REWRITE_DONE(query_string);

	return querytree_list;
}

/*
 * Do parse analysis and rewriting.  This is the same as pg_analyze_and_rewrite
 * except that external-parameter resolution is determined by parser callback
 * hooks instead of a fixed list of parameter datatypes.
 */
List *
pg_analyze_and_rewrite_params(Node *parsetree,
							  const char *query_string,
							  ParserSetupHook parserSetup,
							  void *parserSetupArg)
{
	ParseState *pstate;
	Query	   *query;
	List	   *querytree_list;

	Assert(query_string != NULL);		/* required as of 8.4 */

	TRACE_POSTGRESQL_QUERY_REWRITE_START(query_string);

	/*
	 * (1) Perform parse analysis.
	 */
	if (log_parser_stats)
		ResetUsage();

	pstate = make_parsestate(NULL);
	pstate->p_sourcetext = query_string;
	(*parserSetup) (pstate, parserSetupArg);

	query = transformTopLevelStmt(pstate, parsetree);

	if (post_parse_analyze_hook)
		(*post_parse_analyze_hook) (pstate, query);

	free_parsestate(pstate);

	if (log_parser_stats)
		ShowUsage("PARSE ANALYSIS STATISTICS");

	/*
	 * (2) Rewrite the queries, as necessary
	 */
	querytree_list = pg_rewrite_query(query);

	TRACE_POSTGRESQL_QUERY_REWRITE_DONE(query_string);

	return querytree_list;
}

/*
 * Perform rewriting of a query produced by parse analysis.
 *
 * Note: query must just have come from the parser, because we do not do
 * AcquireRewriteLocks() on it.
 */
static List *
pg_rewrite_query(Query *query)
{
	List	   *querytree_list;

	if (Debug_print_parse)
		elog_node_display(LOG, "parse tree", query,
						  Debug_pretty_print);

	if (log_parser_stats)
		ResetUsage();

	if (query->commandType == CMD_UTILITY)
	{
		/* don't rewrite utilities, just dump 'em into result list */
		querytree_list = list_make1(query);
	}
	else
	{
		/* rewrite regular queries */
		querytree_list = QueryRewrite(query);
	}

	if (log_parser_stats)
		ShowUsage("REWRITER STATISTICS");

#ifdef COPY_PARSE_PLAN_TREES
	/* Optional debugging check: pass querytree output through copyObject() */
	{
		List	   *new_list;

		new_list = (List *) copyObject(querytree_list);
		/* This checks both copyObject() and the equal() routines... */
		if (!equal(new_list, querytree_list))
			elog(WARNING, "copyObject() failed to produce equal parse tree");
		else
			querytree_list = new_list;
	}
#endif

	if (Debug_print_rewritten)
		elog_node_display(LOG, "rewritten parse tree", querytree_list,
						  Debug_pretty_print);

	return querytree_list;
}


/*
 * Generate a plan for a single already-rewritten query.
 * This is a thin wrapper around planner() and takes the same parameters.
 */
PlannedStmt *
pg_plan_query(Query *querytree, int cursorOptions, ParamListInfo boundParams)
{
	PlannedStmt *plan;

	/* Utility commands have no plans. */
	if (querytree->commandType == CMD_UTILITY)
		return NULL;

	/* Planner must have a snapshot in case it calls user-defined functions. */
	Assert(ActiveSnapshotSet());

	TRACE_POSTGRESQL_QUERY_PLAN_START();

	if (log_planner_stats)
		ResetUsage();

	/* call the optimizer */
	plan = planner(querytree, cursorOptions, boundParams);

	if (log_planner_stats)
		ShowUsage("PLANNER STATISTICS");

#ifdef COPY_PARSE_PLAN_TREES
	/* Optional debugging check: pass plan output through copyObject() */
	{
		PlannedStmt *new_plan = (PlannedStmt *) copyObject(plan);

		/*
		 * equal() currently does not have routines to compare Plan nodes, so
		 * don't try to test equality here.  Perhaps fix someday?
		 */
#ifdef NOT_USED
		/* This checks both copyObject() and the equal() routines... */
		if (!equal(new_plan, plan))
			elog(WARNING, "copyObject() failed to produce an equal plan tree");
		else
#endif
			plan = new_plan;
	}
#endif

	/*
	 * Print plan if debugging.
	 */
	if (Debug_print_plan)
		elog_node_display(LOG, "plan", plan, Debug_pretty_print);

	TRACE_POSTGRESQL_QUERY_PLAN_DONE();

	return plan;
}

/*
 * Generate plans for a list of already-rewritten queries.
 *
 * Normal optimizable statements generate PlannedStmt entries in the result
 * list.  Utility statements are simply represented by their statement nodes.
 */
List *
pg_plan_queries(List *querytrees, int cursorOptions, ParamListInfo boundParams)
{
	List	   *stmt_list = NIL;
	ListCell   *query_list;

	foreach(query_list, querytrees)
	{
		Query	   *query = (Query *) lfirst(query_list);
		Node	   *stmt;

		if (query->commandType == CMD_UTILITY)
		{
			/* Utility commands have no plans. */
			stmt = query->utilityStmt;
		}
		else
		{
			stmt = (Node *) pg_plan_query(query, cursorOptions, boundParams);
		}

		stmt_list = lappend(stmt_list, stmt);
	}

	return stmt_list;
}


/*
 * exec_simple_query
 *
 * Execute a "simple Query" protocol message.
 */
static void
exec_simple_query(const char *query_string)
{
	CommandDest dest = whereToSendOutput;
	MemoryContext oldcontext;
	List	   *parsetree_list;
	ListCell   *parsetree_item;
	bool		save_log_statement_stats = log_statement_stats;
	bool		was_logged = false;
	bool		isTopLevel;
	char		msec_str[32];


	/*
	 * Report query to various monitoring facilities.
	 */
	debug_query_string = query_string;

	pgstat_report_activity(STATE_RUNNING, query_string);

	TRACE_POSTGRESQL_QUERY_START(query_string);

	/*
	 * We use save_log_statement_stats so ShowUsage doesn't report incorrect
	 * results because ResetUsage wasn't called.
	 */
	if (save_log_statement_stats)
		ResetUsage();

	/*
	 * Start up a transaction command.  All queries generated by the
	 * query_string will be in this same command block, *unless* we find a
	 * BEGIN/COMMIT/ABORT statement; we have to force a new xact command after
	 * one of those, else bad things will happen in xact.c. (Note that this
	 * will normally change current memory context.)
	 */
	start_xact_command();

	/*
	 * Zap any pre-existing unnamed statement.  (While not strictly necessary,
	 * it seems best to define simple-Query mode as if it used the unnamed
	 * statement and portal; this ensures we recover any storage used by prior
	 * unnamed operations.)
	 */
	drop_unnamed_stmt();

	/*
	 * Switch to appropriate context for constructing parsetrees.
	 */
	oldcontext = MemoryContextSwitchTo(MessageContext);

	/*
	 * Do basic parsing of the query or queries (this should be safe even if
	 * we are in aborted transaction state!)
	 */
	parsetree_list = pg_parse_query(query_string);

	/* Log immediately if dictated by log_statement */
	if (check_log_statement(parsetree_list))
	{
		ereport(LOG,
				(errmsg("statement: %s", query_string),
				 errhidestmt(true),
				 errdetail_execute(parsetree_list)));
		was_logged = true;
	}

	/*
	 * Switch back to transaction context to enter the loop.
	 */
	MemoryContextSwitchTo(oldcontext);

	/*
	 * We'll tell PortalRun it's a top-level command iff there's exactly one
	 * raw parsetree.  If more than one, it's effectively a transaction block
	 * and we want PreventTransactionChain to reject unsafe commands. (Note:
	 * we're assuming that query rewrite cannot add commands that are
	 * significant to PreventTransactionChain.)
	 */
	isTopLevel = (list_length(parsetree_list) == 1);

	/*
	 * Run through the raw parsetree(s) and process each one.
	 */
	foreach(parsetree_item, parsetree_list)
	{
		Node	   *parsetree = (Node *) lfirst(parsetree_item);
		bool		snapshot_set = false;
		const char *commandTag;
		char		completionTag[COMPLETION_TAG_BUFSIZE];
		List	   *querytree_list,
				   *plantree_list;
		Portal		portal;
		DestReceiver *receiver;
		int16		format;

		/*
		 * Get the command name for use in status display (it also becomes the
		 * default completion tag, down inside PortalRun).  Set ps_status and
		 * do any special start-of-SQL-command processing needed by the
		 * destination.
		 */
		commandTag = CreateCommandTag(parsetree);

		set_ps_display(commandTag, false);

		BeginCommand(commandTag, dest);

		/*
		 * If we are in an aborted transaction, reject all commands except
		 * COMMIT/ABORT.  It is important that this test occur before we try
		 * to do parse analysis, rewrite, or planning, since all those phases
		 * try to do database accesses, which may fail in abort state. (It
		 * might be safe to allow some additional utility commands in this
		 * state, but not many...)
		 */
		if (IsAbortedTransactionBlockState() &&
			!IsTransactionExitStmt(parsetree))
			ereport(ERROR,
					(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
					 errmsg("current transaction is aborted, "
						  "commands ignored until end of transaction block"),
					 errdetail_abort()));

		/* Make sure we are in a transaction command */
		start_xact_command();

		/* If we got a cancel signal in parsing or prior command, quit */
		CHECK_FOR_INTERRUPTS();

		/*
		 * Set up a snapshot if parse analysis/planning will need one.
		 */
		if (analyze_requires_snapshot(parsetree))
		{
			PushActiveSnapshot(GetTransactionSnapshot());
			snapshot_set = true;
		}

		/*
		 * OK to analyze, rewrite, and plan this query.
		 *
		 * Switch to appropriate context for constructing querytrees (again,
		 * these must outlive the execution context).
		 */
		oldcontext = MemoryContextSwitchTo(MessageContext);

		querytree_list = pg_analyze_and_rewrite(parsetree, query_string,
												NULL, 0);

		plantree_list = pg_plan_queries(querytree_list, 0, NULL);

		/* Done with the snapshot used for parsing/planning */
		if (snapshot_set)
			PopActiveSnapshot();

		/* If we got a cancel signal in analysis or planning, quit */
		CHECK_FOR_INTERRUPTS();

		/*
		 * Create unnamed portal to run the query or queries in. If there
		 * already is one, silently drop it.
		 */
		portal = CreatePortal("", true, true);
		/* Don't display the portal in pg_cursors */
		portal->visible = false;

		/*
		 * We don't have to copy anything into the portal, because everything
		 * we are passing here is in MessageContext, which will outlive the
		 * portal anyway.
		 */
		PortalDefineQuery(portal,
						  NULL,
						  query_string,
						  commandTag,
						  plantree_list,
						  NULL);

		/*
		 * Start the portal.  No parameters here.
		 */
		PortalStart(portal, NULL, 0, InvalidSnapshot);

		/*
		 * Select the appropriate output format: text unless we are doing a
		 * FETCH from a binary cursor.  (Pretty grotty to have to do this here
		 * --- but it avoids grottiness in other places.  Ah, the joys of
		 * backward compatibility...)
		 */
		format = 0;				/* TEXT is default */
		if (IsA(parsetree, FetchStmt))
		{
			FetchStmt  *stmt = (FetchStmt *) parsetree;

			if (!stmt->ismove)
			{
				Portal		fportal = GetPortalByName(stmt->portalname);

				if (PortalIsValid(fportal) &&
					(fportal->cursorOptions & CURSOR_OPT_BINARY))
					format = 1; /* BINARY */
			}
		}
		PortalSetResultFormat(portal, 1, &format);

		/*
		 * Now we can create the destination receiver object.
		 */
		receiver = CreateDestReceiver(dest);
		if (dest == DestRemote)
			SetRemoteDestReceiverParams(receiver, portal);

		/*
		 * Switch back to transaction context for execution.
		 */
		MemoryContextSwitchTo(oldcontext);

		/*
		 * Run the portal to completion, and then drop it (and the receiver).
		 */
		(void) PortalRun(portal,
						 FETCH_ALL,
						 isTopLevel,
						 receiver,
						 receiver,
						 completionTag);

		(*receiver->rDestroy) (receiver);

		PortalDrop(portal, false);

		if (IsA(parsetree, TransactionStmt))
		{
			/*
			 * If this was a transaction control statement, commit it. We will
			 * start a new xact command for the next command (if any).
			 */
			finish_xact_command();
		}
		else if (lnext(parsetree_item) == NULL)
		{
			/*
			 * If this is the last parsetree of the query string, close down
			 * transaction statement before reporting command-complete.  This
			 * is so that any end-of-transaction errors are reported before
			 * the command-complete message is issued, to avoid confusing
			 * clients who will expect either a command-complete message or an
			 * error, not one and then the other.  But for compatibility with
			 * historical Postgres behavior, we do not force a transaction
			 * boundary between queries appearing in a single query string.
			 */
			finish_xact_command();
		}
		else
		{
			/*
			 * We need a CommandCounterIncrement after every query, except
			 * those that start or end a transaction block.
			 */
			CommandCounterIncrement();
		}

		/*
		 * Tell client that we're done with this query.  Note we emit exactly
		 * one EndCommand report for each raw parsetree, thus one for each SQL
		 * command the client sent, regardless of rewriting. (But a command
		 * aborted by error will not send an EndCommand report at all.)
		 */
		EndCommand(completionTag, dest);
	}							/* end loop over parsetrees */

	/*
	 * Close down transaction statement, if one is open.
	 */
	finish_xact_command();

	/*
	 * If there were no parsetrees, return EmptyQueryResponse message.
	 */
	if (!parsetree_list)
		NullCommand(dest);

	/*
	 * Emit duration logging if appropriate.
	 */
	switch (check_log_duration(msec_str, was_logged))
	{
		case 1:
			ereport(LOG,
					(errmsg("duration: %s ms", msec_str),
					 errhidestmt(true)));
			break;
		case 2:
			ereport(LOG,
					(errmsg("duration: %s ms  statement: %s",
							msec_str, query_string),
					 errhidestmt(true),
					 errdetail_execute(parsetree_list)));
			break;
	}

	if (save_log_statement_stats)
		ShowUsage("QUERY STATISTICS");

	TRACE_POSTGRESQL_QUERY_DONE(query_string);

	debug_query_string = NULL;
}

/*
 * exec_parse_message
 *
 * Execute a "Parse" protocol message.
 */
static void
exec_parse_message(const char *query_string,	/* string to execute */
				   const char *stmt_name,		/* name for prepared stmt */
				   Oid *paramTypes,		/* parameter types */
				   int numParams)		/* number of parameters */
{
	MemoryContext unnamed_stmt_context = NULL;
	MemoryContext oldcontext;
	List	   *parsetree_list;
	Node	   *raw_parse_tree;
	const char *commandTag;
	List	   *querytree_list;
	CachedPlanSource *psrc;
	bool		is_named;
	bool		save_log_statement_stats = log_statement_stats;
	char		msec_str[32];

	/*
	 * Report query to various monitoring facilities.
	 */
	debug_query_string = query_string;

	pgstat_report_activity(STATE_RUNNING, query_string);

	set_ps_display("PARSE", false);

	if (save_log_statement_stats)
		ResetUsage();

	ereport(DEBUG2,
			(errmsg("parse %s: %s",
					*stmt_name ? stmt_name : "<unnamed>",
					query_string)));

	/*
	 * Start up a transaction command so we can run parse analysis etc. (Note
	 * that this will normally change current memory context.) Nothing happens
	 * if we are already in one.
	 */
	start_xact_command();

	/*
	 * Switch to appropriate context for constructing parsetrees.
	 *
	 * We have two strategies depending on whether the prepared statement is
	 * named or not.  For a named prepared statement, we do parsing in
	 * MessageContext and copy the finished trees into the prepared
	 * statement's plancache entry; then the reset of MessageContext releases
	 * temporary space used by parsing and rewriting. For an unnamed prepared
	 * statement, we assume the statement isn't going to hang around long, so
	 * getting rid of temp space quickly is probably not worth the costs of
	 * copying parse trees.  So in this case, we create the plancache entry's
	 * query_context here, and do all the parsing work therein.
	 */
	is_named = (stmt_name[0] != '\0');
	if (is_named)
	{
		/* Named prepared statement --- parse in MessageContext */
		oldcontext = MemoryContextSwitchTo(MessageContext);
	}
	else
	{
		/* Unnamed prepared statement --- release any prior unnamed stmt */
		drop_unnamed_stmt();
		/* Create context for parsing */
		unnamed_stmt_context =
			AllocSetContextCreate(MessageContext,
								  "unnamed prepared statement",
								  ALLOCSET_DEFAULT_MINSIZE,
								  ALLOCSET_DEFAULT_INITSIZE,
								  ALLOCSET_DEFAULT_MAXSIZE);
		oldcontext = MemoryContextSwitchTo(unnamed_stmt_context);
	}

	/*
	 * Do basic parsing of the query or queries (this should be safe even if
	 * we are in aborted transaction state!)
	 */
	parsetree_list = pg_parse_query(query_string);

	/*
	 * We only allow a single user statement in a prepared statement. This is
	 * mainly to keep the protocol simple --- otherwise we'd need to worry
	 * about multiple result tupdescs and things like that.
	 */
	if (list_length(parsetree_list) > 1)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
		errmsg("cannot insert multiple commands into a prepared statement")));

	if (parsetree_list != NIL)
	{
		Query	   *query;
		bool		snapshot_set = false;
		int			i;

		raw_parse_tree = (Node *) linitial(parsetree_list);

		/*
		 * Get the command name for possible use in status display.
		 */
		commandTag = CreateCommandTag(raw_parse_tree);

		/*
		 * If we are in an aborted transaction, reject all commands except
		 * COMMIT/ROLLBACK.  It is important that this test occur before we
		 * try to do parse analysis, rewrite, or planning, since all those
		 * phases try to do database accesses, which may fail in abort state.
		 * (It might be safe to allow some additional utility commands in this
		 * state, but not many...)
		 */
		if (IsAbortedTransactionBlockState() &&
			!IsTransactionExitStmt(raw_parse_tree))
			ereport(ERROR,
					(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
					 errmsg("current transaction is aborted, "
						  "commands ignored until end of transaction block"),
					 errdetail_abort()));

		/*
		 * Create the CachedPlanSource before we do parse analysis, since it
		 * needs to see the unmodified raw parse tree.
		 */
		psrc = CreateCachedPlan(raw_parse_tree, query_string, commandTag);

		/*
		 * Set up a snapshot if parse analysis will need one.
		 */
		if (analyze_requires_snapshot(raw_parse_tree))
		{
			PushActiveSnapshot(GetTransactionSnapshot());
			snapshot_set = true;
		}

		/*
		 * Analyze and rewrite the query.  Note that the originally specified
		 * parameter set is not required to be complete, so we have to use
		 * parse_analyze_varparams().
		 */
		if (log_parser_stats)
			ResetUsage();

		query = parse_analyze_varparams(raw_parse_tree,
										query_string,
										&paramTypes,
										&numParams);

		/*
		 * Check all parameter types got determined.
		 */
		for (i = 0; i < numParams; i++)
		{
			Oid			ptype = paramTypes[i];

			if (ptype == InvalidOid || ptype == UNKNOWNOID)
				ereport(ERROR,
						(errcode(ERRCODE_INDETERMINATE_DATATYPE),
					 errmsg("could not determine data type of parameter $%d",
							i + 1)));
		}

		if (log_parser_stats)
			ShowUsage("PARSE ANALYSIS STATISTICS");

		querytree_list = pg_rewrite_query(query);

		/* Done with the snapshot used for parsing */
		if (snapshot_set)
			PopActiveSnapshot();
	}
	else
	{
		/* Empty input string.  This is legal. */
		raw_parse_tree = NULL;
		commandTag = NULL;
		psrc = CreateCachedPlan(raw_parse_tree, query_string, commandTag);
		querytree_list = NIL;
	}

	/*
	 * CachedPlanSource must be a direct child of MessageContext before we
	 * reparent unnamed_stmt_context under it, else we have a disconnected
	 * circular subgraph.  Klugy, but less so than flipping contexts even more
	 * above.
	 */
	if (unnamed_stmt_context)
		MemoryContextSetParent(psrc->context, MessageContext);

	/* Finish filling in the CachedPlanSource */
	CompleteCachedPlan(psrc,
					   querytree_list,
					   unnamed_stmt_context,
					   paramTypes,
					   numParams,
					   NULL,
					   NULL,
					   0,		/* default cursor options */
					   true);	/* fixed result */

	/* If we got a cancel signal during analysis, quit */
	CHECK_FOR_INTERRUPTS();

	if (is_named)
	{
		/*
		 * Store the query as a prepared statement.
		 */
		StorePreparedStatement(stmt_name, psrc, false);
	}
	else
	{
		/*
		 * We just save the CachedPlanSource into unnamed_stmt_psrc.
		 */
		SaveCachedPlan(psrc);
		unnamed_stmt_psrc = psrc;
	}

	MemoryContextSwitchTo(oldcontext);

	/*
	 * We do NOT close the open transaction command here; that only happens
	 * when the client sends Sync.  Instead, do CommandCounterIncrement just
	 * in case something happened during parse/plan.
	 */
	CommandCounterIncrement();

	/*
	 * Send ParseComplete.
	 */
	if (whereToSendOutput == DestRemote)
		pq_putemptymessage('1');

	/*
	 * Emit duration logging if appropriate.
	 */
	switch (check_log_duration(msec_str, false))
	{
		case 1:
			ereport(LOG,
					(errmsg("duration: %s ms", msec_str),
					 errhidestmt(true)));
			break;
		case 2:
			ereport(LOG,
					(errmsg("duration: %s ms  parse %s: %s",
							msec_str,
							*stmt_name ? stmt_name : "<unnamed>",
							query_string),
					 errhidestmt(true)));
			break;
	}

	if (save_log_statement_stats)
		ShowUsage("PARSE MESSAGE STATISTICS");

	debug_query_string = NULL;
}

/*
 * exec_bind_message
 *
 * Process a "Bind" message to create a portal from a prepared statement
 */
static void
exec_bind_message(StringInfo input_message)
{
	const char *portal_name;
	const char *stmt_name;
	int			numPFormats;
	int16	   *pformats = NULL;
	int			numParams;
	int			numRFormats;
	int16	   *rformats = NULL;
	CachedPlanSource *psrc;
	CachedPlan *cplan;
	Portal		portal;
	char	   *query_string;
	char	   *saved_stmt_name;
	ParamListInfo params;
	MemoryContext oldContext;
	bool		save_log_statement_stats = log_statement_stats;
	bool		snapshot_set = false;
	char		msec_str[32];

	/* Get the fixed part of the message */
	portal_name = pq_getmsgstring(input_message);
	stmt_name = pq_getmsgstring(input_message);

	ereport(DEBUG2,
			(errmsg("bind %s to %s",
					*portal_name ? portal_name : "<unnamed>",
					*stmt_name ? stmt_name : "<unnamed>")));

	/* Find prepared statement */
	if (stmt_name[0] != '\0')
	{
		PreparedStatement *pstmt;

		pstmt = FetchPreparedStatement(stmt_name, true);
		psrc = pstmt->plansource;
	}
	else
	{
		/* special-case the unnamed statement */
		psrc = unnamed_stmt_psrc;
		if (!psrc)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_PSTATEMENT),
					 errmsg("unnamed prepared statement does not exist")));
	}

	/*
	 * Report query to various monitoring facilities.
	 */
	debug_query_string = psrc->query_string;

	pgstat_report_activity(STATE_RUNNING, psrc->query_string);

	set_ps_display("BIND", false);

	if (save_log_statement_stats)
		ResetUsage();

	/*
	 * Start up a transaction command so we can call functions etc. (Note that
	 * this will normally change current memory context.) Nothing happens if
	 * we are already in one.
	 */
	start_xact_command();

	/* Switch back to message context */
	MemoryContextSwitchTo(MessageContext);

	/* Get the parameter format codes */
	numPFormats = pq_getmsgint(input_message, 2);
	if (numPFormats > 0)
	{
		int			i;

		pformats = (int16 *) palloc(numPFormats * sizeof(int16));
		for (i = 0; i < numPFormats; i++)
			pformats[i] = pq_getmsgint(input_message, 2);
	}

	/* Get the parameter value count */
	numParams = pq_getmsgint(input_message, 2);

	if (numPFormats > 1 && numPFormats != numParams)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
			errmsg("bind message has %d parameter formats but %d parameters",
				   numPFormats, numParams)));

	if (numParams != psrc->num_params)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("bind message supplies %d parameters, but prepared statement \"%s\" requires %d",
						numParams, stmt_name, psrc->num_params)));

	/*
	 * If we are in aborted transaction state, the only portals we can
	 * actually run are those containing COMMIT or ROLLBACK commands. We
	 * disallow binding anything else to avoid problems with infrastructure
	 * that expects to run inside a valid transaction.  We also disallow
	 * binding any parameters, since we can't risk calling user-defined I/O
	 * functions.
	 */
	if (IsAbortedTransactionBlockState() &&
		(!IsTransactionExitStmt(psrc->raw_parse_tree) ||
		 numParams != 0))
		ereport(ERROR,
				(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
				 errmsg("current transaction is aborted, "
						"commands ignored until end of transaction block"),
				 errdetail_abort()));

	/*
	 * Create the portal.  Allow silent replacement of an existing portal only
	 * if the unnamed portal is specified.
	 */
	if (portal_name[0] == '\0')
		portal = CreatePortal(portal_name, true, true);
	else
		portal = CreatePortal(portal_name, false, false);

	/*
	 * Prepare to copy stuff into the portal's memory context.  We do all this
	 * copying first, because it could possibly fail (out-of-memory) and we
	 * don't want a failure to occur between GetCachedPlan and
	 * PortalDefineQuery; that would result in leaking our plancache refcount.
	 */
	oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));

	/* Copy the plan's query string into the portal */
	query_string = pstrdup(psrc->query_string);

	/* Likewise make a copy of the statement name, unless it's unnamed */
	if (stmt_name[0])
		saved_stmt_name = pstrdup(stmt_name);
	else
		saved_stmt_name = NULL;

	/*
	 * Set a snapshot if we have parameters to fetch (since the input
	 * functions might need it) or the query isn't a utility command (and
	 * hence could require redoing parse analysis and planning).  We keep the
	 * snapshot active till we're done, so that plancache.c doesn't have to
	 * take new ones.
	 */
	if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree))
	{
		PushActiveSnapshot(GetTransactionSnapshot());
		snapshot_set = true;
	}

	/*
	 * Fetch parameters, if any, and store in the portal's memory context.
	 */
	if (numParams > 0)
	{
		int			paramno;

		/* sizeof(ParamListInfoData) includes the first array element */
		params = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
								  (numParams - 1) * sizeof(ParamExternData));
		/* we have static list of params, so no hooks needed */
		params->paramFetch = NULL;
		params->paramFetchArg = NULL;
		params->parserSetup = NULL;
		params->parserSetupArg = NULL;
		params->numParams = numParams;

		for (paramno = 0; paramno < numParams; paramno++)
		{
			Oid			ptype = psrc->param_types[paramno];
			int32		plength;
			Datum		pval;
			bool		isNull;
			StringInfoData pbuf;
			char		csave;
			int16		pformat;

			plength = pq_getmsgint(input_message, 4);
			isNull = (plength == -1);

			if (!isNull)
			{
				const char *pvalue = pq_getmsgbytes(input_message, plength);

				/*
				 * Rather than copying data around, we just set up a phony
				 * StringInfo pointing to the correct portion of the message
				 * buffer.  We assume we can scribble on the message buffer so
				 * as to maintain the convention that StringInfos have a
				 * trailing null.  This is grotty but is a big win when
				 * dealing with very large parameter strings.
				 */
				pbuf.data = (char *) pvalue;
				pbuf.maxlen = plength + 1;
				pbuf.len = plength;
				pbuf.cursor = 0;

				csave = pbuf.data[plength];
				pbuf.data[plength] = '\0';
			}
			else
			{
				pbuf.data = NULL;		/* keep compiler quiet */
				csave = 0;
			}

			if (numPFormats > 1)
				pformat = pformats[paramno];
			else if (numPFormats > 0)
				pformat = pformats[0];
			else
				pformat = 0;	/* default = text */

			if (pformat == 0)	/* text mode */
			{
				Oid			typinput;
				Oid			typioparam;
				char	   *pstring;

				getTypeInputInfo(ptype, &typinput, &typioparam);

				/*
				 * We have to do encoding conversion before calling the
				 * typinput routine.
				 */
				if (isNull)
					pstring = NULL;
				else
					pstring = pg_client_to_server(pbuf.data, plength);

				pval = OidInputFunctionCall(typinput, pstring, typioparam, -1);

				/* Free result of encoding conversion, if any */
				if (pstring && pstring != pbuf.data)
					pfree(pstring);
			}
			else if (pformat == 1)		/* binary mode */
			{
				Oid			typreceive;
				Oid			typioparam;
				StringInfo	bufptr;

				/*
				 * Call the parameter type's binary input converter
				 */
				getTypeBinaryInputInfo(ptype, &typreceive, &typioparam);

				if (isNull)
					bufptr = NULL;
				else
					bufptr = &pbuf;

				pval = OidReceiveFunctionCall(typreceive, bufptr, typioparam, -1);

				/* Trouble if it didn't eat the whole buffer */
				if (!isNull && pbuf.cursor != pbuf.len)
					ereport(ERROR,
							(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
							 errmsg("incorrect binary data format in bind parameter %d",
									paramno + 1)));
			}
			else
			{
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("unsupported format code: %d",
								pformat)));
				pval = 0;		/* keep compiler quiet */
			}

			/* Restore message buffer contents */
			if (!isNull)
				pbuf.data[plength] = csave;

			params->params[paramno].value = pval;
			params->params[paramno].isnull = isNull;

			/*
			 * We mark the params as CONST.  This ensures that any custom plan
			 * makes full use of the parameter values.
			 */
			params->params[paramno].pflags = PARAM_FLAG_CONST;
			params->params[paramno].ptype = ptype;
		}
	}
	else
		params = NULL;

	/* Done storing stuff in portal's context */
	MemoryContextSwitchTo(oldContext);

	/* Get the result format codes */
	numRFormats = pq_getmsgint(input_message, 2);
	if (numRFormats > 0)
	{
		int			i;

		rformats = (int16 *) palloc(numRFormats * sizeof(int16));
		for (i = 0; i < numRFormats; i++)
			rformats[i] = pq_getmsgint(input_message, 2);
	}

	pq_getmsgend(input_message);

	/*
	 * Obtain a plan from the CachedPlanSource.  Any cruft from (re)planning
	 * will be generated in MessageContext.  The plan refcount will be
	 * assigned to the Portal, so it will be released at portal destruction.
	 */
	cplan = GetCachedPlan(psrc, params, false);

	/*
	 * Now we can define the portal.
	 *
	 * DO NOT put any code that could possibly throw an error between the
	 * above GetCachedPlan call and here.
	 */
	PortalDefineQuery(portal,
					  saved_stmt_name,
					  query_string,
					  psrc->commandTag,
					  cplan->stmt_list,
					  cplan);

	/* Done with the snapshot used for parameter I/O and parsing/planning */
	if (snapshot_set)
		PopActiveSnapshot();

	/*
	 * And we're ready to start portal execution.
	 */
	PortalStart(portal, params, 0, InvalidSnapshot);

	/*
	 * Apply the result format requests to the portal.
	 */
	PortalSetResultFormat(portal, numRFormats, rformats);

	/*
	 * Send BindComplete.
	 */
	if (whereToSendOutput == DestRemote)
		pq_putemptymessage('2');

	/*
	 * Emit duration logging if appropriate.
	 */
	switch (check_log_duration(msec_str, false))
	{
		case 1:
			ereport(LOG,
					(errmsg("duration: %s ms", msec_str),
					 errhidestmt(true)));
			break;
		case 2:
			ereport(LOG,
					(errmsg("duration: %s ms  bind %s%s%s: %s",
							msec_str,
							*stmt_name ? stmt_name : "<unnamed>",
							*portal_name ? "/" : "",
							*portal_name ? portal_name : "",
							psrc->query_string),
					 errhidestmt(true),
					 errdetail_params(params)));
			break;
	}

	if (save_log_statement_stats)
		ShowUsage("BIND MESSAGE STATISTICS");

	debug_query_string = NULL;
}

/*
 * exec_execute_message
 *
 * Process an "Execute" message for a portal
 */
static void
exec_execute_message(const char *portal_name, long max_rows)
{
	CommandDest dest;
	DestReceiver *receiver;
	Portal		portal;
	bool		completed;
	char		completionTag[COMPLETION_TAG_BUFSIZE];
	const char *sourceText;
	const char *prepStmtName;
	ParamListInfo portalParams;
	bool		save_log_statement_stats = log_statement_stats;
	bool		is_xact_command;
	bool		execute_is_fetch;
	bool		was_logged = false;
	char		msec_str[32];

	/* Adjust destination to tell printtup.c what to do */
	dest = whereToSendOutput;
	if (dest == DestRemote)
		dest = DestRemoteExecute;

	portal = GetPortalByName(portal_name);
	if (!PortalIsValid(portal))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_CURSOR),
				 errmsg("portal \"%s\" does not exist", portal_name)));

	/*
	 * If the original query was a null string, just return
	 * EmptyQueryResponse.
	 */
	if (portal->commandTag == NULL)
	{
		Assert(portal->stmts == NIL);
		NullCommand(dest);
		return;
	}

	/* Does the portal contain a transaction command? */
	is_xact_command = IsTransactionStmtList(portal->stmts);

	/*
	 * We must copy the sourceText and prepStmtName into MessageContext in
	 * case the portal is destroyed during finish_xact_command. Can avoid the
	 * copy if it's not an xact command, though.
	 */
	if (is_xact_command)
	{
		sourceText = pstrdup(portal->sourceText);
		if (portal->prepStmtName)
			prepStmtName = pstrdup(portal->prepStmtName);
		else
			prepStmtName = "<unnamed>";

		/*
		 * An xact command shouldn't have any parameters, which is a good
		 * thing because they wouldn't be around after finish_xact_command.
		 */
		portalParams = NULL;
	}
	else
	{
		sourceText = portal->sourceText;
		if (portal->prepStmtName)
			prepStmtName = portal->prepStmtName;
		else
			prepStmtName = "<unnamed>";
		portalParams = portal->portalParams;
	}

	/*
	 * Report query to various monitoring facilities.
	 */
	debug_query_string = sourceText;

	pgstat_report_activity(STATE_RUNNING, sourceText);

	set_ps_display(portal->commandTag, false);

	if (save_log_statement_stats)
		ResetUsage();

	BeginCommand(portal->commandTag, dest);

	/*
	 * Create dest receiver in MessageContext (we don't want it in transaction
	 * context, because that may get deleted if portal contains VACUUM).
	 */
	receiver = CreateDestReceiver(dest);
	if (dest == DestRemoteExecute)
		SetRemoteDestReceiverParams(receiver, portal);

	/*
	 * Ensure we are in a transaction command (this should normally be the
	 * case already due to prior BIND).
	 */
	start_xact_command();

	/*
	 * If we re-issue an Execute protocol requ…

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