From a84069d9350400c860d5e932b50dfd337aa407b0 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Tue, 24 Jan 2017 16:53:56 -0500 Subject: [PATCH] Add a new DestReceiver for printing tuples without catalog access. If you create a DestReciver of type DestRemote and try to use it from a replication connection that is not bound to a specific daabase, or any other hypothetical type of backend that is not bound to a specific database, it will fail because it doesn't have a pg_proc catalog to look up properties of the types being printed. In general, that's an unavoidable problem, but we can hardwire the properties of a few builtin types in order to support utility commands. This new DestReceiver of type DestRemoteSimple does just that. Patch by me, reviewed by Michael Paquier. Discussion: http://postgr.es/m/CA+TgmobNo4qz06wHEmy9DszAre3dYx-WNhHSCbU9SAwf+9Ft6g@mail.gmail.com --- src/backend/access/common/Makefile | 4 +- src/backend/access/common/printsimple.c | 110 ++++++++++++++++++++++++ src/backend/tcop/dest.c | 12 +++ src/include/access/printsimple.h | 23 +++++ src/include/tcop/dest.h | 1 + 5 files changed, 148 insertions(+), 2 deletions(-) create mode 100644 src/backend/access/common/printsimple.c create mode 100644 src/include/access/printsimple.h diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile index 1fa6de0823..d4b8132a97 100644 --- a/src/backend/access/common/Makefile +++ b/src/backend/access/common/Makefile @@ -12,7 +12,7 @@ subdir = src/backend/access/common top_builddir = ../../../.. include $(top_builddir)/src/Makefile.global -OBJS = heaptuple.o indextuple.o printtup.o reloptions.o scankey.o \ - tupconvert.o tupdesc.o +OBJS = heaptuple.o indextuple.o printsimple.o printtup.o reloptions.o \ + scankey.o tupconvert.o tupdesc.o include $(top_srcdir)/src/backend/common.mk diff --git a/src/backend/access/common/printsimple.c b/src/backend/access/common/printsimple.c new file mode 100644 index 0000000000..420de65e20 --- /dev/null +++ b/src/backend/access/common/printsimple.c @@ -0,0 +1,110 @@ +/*------------------------------------------------------------------------- + * + * printsimple.c + * Routines to print out tuples containing only a limited range of + * builtin types without catalog access. This is intended for + * backends that don't have catalog access because they are not bound + * to a specific database, such as some walsender processes. It + * doesn't handle standalone backends or protocol versions other than + * 3.0, because we don't need such handling for current applications. + * + * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/access/common/printsimple.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/printsimple.h" +#include "catalog/pg_type.h" +#include "fmgr.h" +#include "libpq/pqformat.h" + +/* + * At startup time, send a RowDescription message. + */ +void +printsimple_startup(DestReceiver *self, int operation, TupleDesc tupdesc) +{ + StringInfoData buf; + int i; + + pq_beginmessage(&buf, 'T'); /* RowDescription */ + pq_sendint(&buf, tupdesc->natts, 2); + + for (i = 0; i < tupdesc->natts; ++i) + { + Form_pg_attribute attr = tupdesc->attrs[i]; + + pq_sendstring(&buf, NameStr(attr->attname)); + pq_sendint(&buf, 0, 4); /* table oid */ + pq_sendint(&buf, 0, 2); /* attnum */ + pq_sendint(&buf, (int) attr->atttypid, 4); + pq_sendint(&buf, attr->attlen, 2); + pq_sendint(&buf, attr->atttypmod, 4); + pq_sendint(&buf, 0, 2); /* format code */ + } + + pq_endmessage(&buf); +} + +/* + * For each tuple, send a DataRow message. + */ +bool +printsimple(TupleTableSlot *slot, DestReceiver *self) +{ + TupleDesc tupdesc = slot->tts_tupleDescriptor; + StringInfoData buf; + int i; + + /* Make sure the tuple is fully deconstructed */ + slot_getallattrs(slot); + + /* Prepare and send message */ + pq_beginmessage(&buf, 'D'); + pq_sendint(&buf, tupdesc->natts, 2); + + for (i = 0; i < tupdesc->natts; ++i) + { + Form_pg_attribute attr = tupdesc->attrs[i]; + Datum value; + + if (slot->tts_isnull[i]) + { + pq_sendint(&buf, -1, 4); + continue; + } + + value = slot->tts_values[i]; + + /* + * We can't call the regular type output functions here because we + * might not have catalog access. Instead, we must hard-wire + * knowledge of the required types. + */ + switch (attr->atttypid) + { + case TEXTOID: + { + text *t = DatumGetTextPP(value); + + pq_sendcountedtext(&buf, + VARDATA_ANY(t), + VARSIZE_ANY_EXHDR(t), + false); + } + break; + + default: + elog(ERROR, "unsupported type OID: %u", attr->atttypid); + } + } + + pq_endmessage(&buf); + + return true; +} diff --git a/src/backend/tcop/dest.c b/src/backend/tcop/dest.c index da39f43f38..28081c3765 100644 --- a/src/backend/tcop/dest.c +++ b/src/backend/tcop/dest.c @@ -28,6 +28,7 @@ #include "postgres.h" +#include "access/printsimple.h" #include "access/printtup.h" #include "access/xact.h" #include "commands/copy.h" @@ -76,6 +77,11 @@ static DestReceiver debugtupDR = { DestDebug }; +static DestReceiver printsimpleDR = { + printsimple, printsimple_startup, donothingCleanup, donothingCleanup, + DestRemoteSimple +}; + static DestReceiver spi_printtupDR = { spi_printtup, spi_dest_startup, donothingCleanup, donothingCleanup, DestSPI @@ -108,6 +114,9 @@ CreateDestReceiver(CommandDest dest) case DestRemoteExecute: return printtup_create_DR(dest); + case DestRemoteSimple: + return &printsimpleDR; + case DestNone: return &donothingDR; @@ -151,6 +160,7 @@ EndCommand(const char *commandTag, CommandDest dest) { case DestRemote: case DestRemoteExecute: + case DestRemoteSimple: /* * We assume the commandTag is plain ASCII and therefore requires @@ -191,6 +201,7 @@ NullCommand(CommandDest dest) { case DestRemote: case DestRemoteExecute: + case DestRemoteSimple: /* * tell the fe that we saw an empty query string. In protocols @@ -233,6 +244,7 @@ ReadyForQuery(CommandDest dest) { case DestRemote: case DestRemoteExecute: + case DestRemoteSimple: if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3) { StringInfoData buf; diff --git a/src/include/access/printsimple.h b/src/include/access/printsimple.h new file mode 100644 index 0000000000..3f3e7a3840 --- /dev/null +++ b/src/include/access/printsimple.h @@ -0,0 +1,23 @@ +/*------------------------------------------------------------------------- + * + * printsimple.h + * print simple tuples without catalog access + * + * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/access/printsimple.h + * + *------------------------------------------------------------------------- + */ + +#ifndef PRINTSIMPLE_H +#define PRINTSIMPLE_H + +#include "tcop/dest.h" + +extern bool printsimple(TupleTableSlot *slot, DestReceiver *self); +extern void printsimple_startup(DestReceiver *self, int operation, + TupleDesc tupdesc); + +#endif /* PRINTSIMPLE_H */ diff --git a/src/include/tcop/dest.h b/src/include/tcop/dest.h index 93f9b7463a..c459af2e13 100644 --- a/src/include/tcop/dest.h +++ b/src/include/tcop/dest.h @@ -89,6 +89,7 @@ typedef enum DestDebug, /* results go to debugging output */ DestRemote, /* results sent to frontend process */ DestRemoteExecute, /* sent to frontend, in Execute command */ + DestRemoteSimple, /* sent to frontend, w/no catalog access */ DestSPI, /* results sent to SPI manager */ DestTuplestore, /* results sent to Tuplestore */ DestIntoRel, /* results sent to relation (SELECT INTO) */