greenplumn printtup 源码
greenplumn printtup 代码
文件路径：/src/backend/access/common/printtup.c
/*-------------------------------------------------------------------------
*
* printtup.c
* Routines to print out tuples to the destination (both frontend
* clients and standalone backends are supported here).
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/common/printtup.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/printtup.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "tcop/pquery.h"
#include "utils/lsyscache.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
static void printtup_startup(DestReceiver *self, int operation,
TupleDesc typeinfo);
static bool printtup(TupleTableSlot *slot, DestReceiver *self);
static bool printtup_20(TupleTableSlot *slot, DestReceiver *self);
static bool printtup_internal_20(TupleTableSlot *slot, DestReceiver *self);
static void printtup_shutdown(DestReceiver *self);
static void printtup_destroy(DestReceiver *self);
static void SendRowDescriptionCols_2(StringInfo buf, TupleDesc typeinfo,
List *targetlist, int16 *formats);
static void SendRowDescriptionCols_3(StringInfo buf, TupleDesc typeinfo,
List *targetlist, int16 *formats);
/* ----------------------------------------------------------------
* printtup / debugtup support
* ----------------------------------------------------------------
*/
/* ----------------
* Private state for a printtup destination object
*
* NOTE: finfo is the lookup info for either typoutput or typsend, whichever
* we are using for this column.
* ----------------
*/
typedef struct
{ /* Per-attribute information */
Oid typoutput; /* Oid for the type's text output fn */
Oid typsend; /* Oid for the type's binary output fn */
bool typisvarlena; /* is it varlena (ie possibly toastable)? */
int16 format; /* format code for this column */
FmgrInfo finfo; /* Precomputed call info for output fn */
} PrinttupAttrInfo;
typedef struct
{
DestReceiver pub; /* publicly-known function pointers */
Portal portal; /* the Portal we are printing from */
bool sendDescrip; /* send RowDescription at startup? */
TupleDesc attrinfo; /* The attr info we are set up for */
int nattrs;
PrinttupAttrInfo *myinfo; /* Cached info about each attr */
StringInfoData buf; /* output buffer (*not* in tmpcontext) */
MemoryContext tmpcontext; /* Memory context for per-row workspace */
} DR_printtup;
/* ----------------
* Initialize: create a DestReceiver for printtup
* ----------------
*/
DestReceiver *
printtup_create_DR(CommandDest dest)
{
DR_printtup *self = (DR_printtup *) palloc0(sizeof(DR_printtup));
self->pub.receiveSlot = printtup; /* might get changed later */
self->pub.rStartup = printtup_startup;
self->pub.rShutdown = printtup_shutdown;
self->pub.rDestroy = printtup_destroy;
self->pub.mydest = dest;
/*
* Send T message automatically if DestRemote, but not if
* DestRemoteExecute
*/
self->sendDescrip = (dest == DestRemote);
self->attrinfo = NULL;
self->nattrs = 0;
self->myinfo = NULL;
self->buf.data = NULL;
self->tmpcontext = NULL;
return (DestReceiver *) self;
}
/*
* Set parameters for a DestRemote (or DestRemoteExecute) receiver
*/
void
SetRemoteDestReceiverParams(DestReceiver *self, Portal portal)
{
DR_printtup *myState = (DR_printtup *) self;
Assert(myState->pub.mydest == DestRemote ||
myState->pub.mydest == DestRemoteExecute);
myState->portal = portal;
if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
{
/*
* In protocol 2.0 the Bind message does not exist, so there is no way
* for the columns to have different print formats; it's sufficient to
* look at the first one.
*/
if (portal->formats && portal->formats[0] != 0)
myState->pub.receiveSlot = printtup_internal_20;
else
myState->pub.receiveSlot = printtup_20;
}
}
static void
printtup_startup(DestReceiver *self, int operation pg_attribute_unused(), TupleDesc typeinfo)
{
DR_printtup *myState = (DR_printtup *) self;
Portal portal = myState->portal;
/*
* Create I/O buffer to be used for all messages. This cannot be inside
* tmpcontext, since we want to re-use it across rows.
*/
initStringInfo(&myState->buf);
/*
* Create a temporary memory context that we can reset once per row to
* recover palloc'd memory. This avoids any problems with leaks inside
* datatype output routines, and should be faster than retail pfree's
* anyway.
*/
myState->tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
"printtup",
ALLOCSET_DEFAULT_SIZES);
if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
{
/*
* Send portal name to frontend (obsolete cruft, gone in proto 3.0)
*
* If portal name not specified, use "blank" portal.
*/
const char *portalName = portal->name;
if (portalName == NULL || portalName[0] == '\0')
portalName = "blank";
pq_puttextmessage('P', portalName);
}
/*
* If we are supposed to emit row descriptions, then send the tuple
* descriptor of the tuples.
*/
if (myState->sendDescrip)
SendRowDescriptionMessage(&myState->buf,
typeinfo,
FetchPortalTargetList(portal),
portal->formats);
/* ----------------
* We could set up the derived attr info at this time, but we postpone it
* until the first call of printtup, for 2 reasons:
* 1. We don't waste time (compared to the old way) if there are no
* tuples at all to output.
* 2. Checking in printtup allows us to handle the case that the tuples
* change type midway through (although this probably can't happen in
* the current executor).
* ----------------
*/
}
/*
* SendRowDescriptionMessage --- send a RowDescription message to the frontend
*
* Notes: the TupleDesc has typically been manufactured by ExecTypeFromTL()
* or some similar function; it does not contain a full set of fields.
* The targetlist will be NIL when executing a utility function that does
* not have a plan. If the targetlist isn't NIL then it is a Query node's
* targetlist; it is up to us to ignore resjunk columns in it. The formats[]
* array pointer might be NULL (if we are doing Describe on a prepared stmt);
* send zeroes for the format codes in that case.
*/
void
SendRowDescriptionMessage(StringInfo buf, TupleDesc typeinfo,
List *targetlist, int16 *formats)
{
int natts = typeinfo->natts;
int proto = PG_PROTOCOL_MAJOR(FrontendProtocol);
/* tuple descriptor message type */
pq_beginmessage_reuse(buf, 'T');
/* # of attrs in tuples */
pq_sendint16(buf, natts);
if (proto >= 3)
SendRowDescriptionCols_3(buf, typeinfo, targetlist, formats);
else
SendRowDescriptionCols_2(buf, typeinfo, targetlist, formats);
pq_endmessage_reuse(buf);
}
/*
* Send description for each column when using v3+ protocol
*/
static void
SendRowDescriptionCols_3(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats)
{
int natts = typeinfo->natts;
int i;
ListCell *tlist_item = list_head(targetlist);
/*
* Preallocate memory for the entire message to be sent. That allows to
* use the significantly faster inline pqformat.h functions and to avoid
* reallocations.
*
* Have to overestimate the size of the column-names, to account for
* character set overhead.
*/
enlargeStringInfo(buf, (NAMEDATALEN * MAX_CONVERSION_GROWTH /* attname */
+ sizeof(Oid) /* resorigtbl */
+ sizeof(AttrNumber) /* resorigcol */
+ sizeof(Oid) /* atttypid */
+ sizeof(int16) /* attlen */
+ sizeof(int32) /* attypmod */
+ sizeof(int16) /* format */
) * natts);
for (i = 0; i < natts; ++i)
{
Form_pg_attribute att = TupleDescAttr(typeinfo, i);
Oid atttypid = att->atttypid;
int32 atttypmod = att->atttypmod;
Oid resorigtbl;
AttrNumber resorigcol;
int16 format;
/*
* If column is a domain, send the base type and typmod instead.
* Lookup before sending any ints, for efficiency.
*/
atttypid = getBaseTypeAndTypmod(atttypid, &atttypmod);
/* Do we have a non-resjunk tlist item? */
while (tlist_item &&
((TargetEntry *) lfirst(tlist_item))->resjunk)
tlist_item = lnext(tlist_item);
if (tlist_item)
{
TargetEntry *tle = (TargetEntry *) lfirst(tlist_item);
resorigtbl = tle->resorigtbl;
resorigcol = tle->resorigcol;
tlist_item = lnext(tlist_item);
}
else
{
/* No info available, so send zeroes */
resorigtbl = 0;
resorigcol = 0;
}
if (formats)
format = formats[i];
else
format = 0;
pq_writestring(buf, NameStr(att->attname));
pq_writeint32(buf, resorigtbl);
pq_writeint16(buf, resorigcol);
pq_writeint32(buf, atttypid);
pq_writeint16(buf, att->attlen);
pq_writeint32(buf, atttypmod);
pq_writeint16(buf, format);
}
}
/*
* Send description for each column when using v2 protocol
*/
static void
SendRowDescriptionCols_2(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats)
{
int natts = typeinfo->natts;
int i;
for (i = 0; i < natts; ++i)
{
Form_pg_attribute att = TupleDescAttr(typeinfo, i);
Oid atttypid = att->atttypid;
int32 atttypmod = att->atttypmod;
/* If column is a domain, send the base type and typmod instead */
atttypid = getBaseTypeAndTypmod(atttypid, &atttypmod);
pq_sendstring(buf, NameStr(att->attname));
/* column ID only info appears in protocol 3.0 and up */
pq_sendint32(buf, atttypid);
pq_sendint16(buf, att->attlen);
pq_sendint32(buf, atttypmod);
/* format info only appears in protocol 3.0 and up */
}
}
/*
* Get the lookup info that printtup() needs
*/
static void
printtup_prepare_info(DR_printtup *myState, TupleDesc typeinfo, int numAttrs)
{
int16 *formats = myState->portal->formats;
int i;
/* get rid of any old data */
if (myState->myinfo)
pfree(myState->myinfo);
myState->myinfo = NULL;
myState->attrinfo = typeinfo;
myState->nattrs = numAttrs;
if (numAttrs <= 0)
return;
myState->myinfo = (PrinttupAttrInfo *)
palloc0(numAttrs * sizeof(PrinttupAttrInfo));
for (i = 0; i < numAttrs; i++)
{
PrinttupAttrInfo *thisState = myState->myinfo + i;
int16 format = (formats ? formats[i] : 0);
Form_pg_attribute attr = TupleDescAttr(typeinfo, i);
thisState->format = format;
if (format == 0)
{
getTypeOutputInfo(attr->atttypid,
&thisState->typoutput,
&thisState->typisvarlena);
fmgr_info(thisState->typoutput, &thisState->finfo);
}
else if (format == 1)
{
getTypeBinaryOutputInfo(attr->atttypid,
&thisState->typsend,
&thisState->typisvarlena);
fmgr_info(thisState->typsend, &thisState->finfo);
}
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unsupported format code: %d", format)));
}
}
/* ----------------
* printtup --- print a tuple in protocol 3.0
* ----------------
*/
static bool
printtup(TupleTableSlot *slot, DestReceiver *self)
{
TupleDesc typeinfo = slot->tts_tupleDescriptor;
DR_printtup *myState = (DR_printtup *) self;
MemoryContext oldcontext;
StringInfo buf = &myState->buf;
int natts = typeinfo->natts;
int i;
/* Set or update my derived attribute info, if needed */
if (myState->attrinfo != typeinfo || myState->nattrs != natts)
printtup_prepare_info(myState, typeinfo, natts);
/* Make sure the tuple is fully deconstructed */
slot_getallattrs(slot);
/* Switch into per-row context so we can recover memory below */
oldcontext = MemoryContextSwitchTo(myState->tmpcontext);
/*
* Prepare a DataRow message (note buffer is in per-row context)
*/
pq_beginmessage_reuse(buf, 'D');
pq_sendint16(buf, natts);
/*
* send the attributes of this tuple
*/
for (i = 0; i < natts; ++i)
{
PrinttupAttrInfo *thisState = myState->myinfo + i;
bool isnull;
Datum attr = slot_getattr(slot, i+1, &isnull);
Form_pg_attribute fatt = TupleDescAttr(typeinfo, i);
if (isnull)
{
pq_sendint32(buf, -1);
continue;
}
/*
* Here we catch undefined bytes in datums that are returned to the
* client without hitting disk; see comments at the related check in
* PageAddItem(). This test is most useful for uncompressed,
* non-external datums, but we're quite likely to see such here when
* testing new C functions.
*/
if (thisState->typisvarlena)
VALGRIND_CHECK_MEM_IS_DEFINED(DatumGetPointer(attr),
VARSIZE_ANY(attr));
if (thisState->format == 0)
{
/* Text output */
char str[256];
int32 n32;
switch (fatt->atttypid)
{
case INT2OID: /* int2 */
case INT4OID: /* int4 */
{
/*
* The standard postgres way is to call the output function, but that involves one or more pallocs,
* and a call to sprintf, followed by a conversion to client charset.
* Do a fast conversion to string instead.
*/
char tmp[33];
char *tp = tmp;
char *sp;
long li = 0;
unsigned long v;
long value;
bool sign;
if (fatt->atttypid == INT2OID)
value =(long)DatumGetInt16(attr);
else
value =(long)DatumGetInt32(attr);
sign = (value < 0);
if (sign)
v = -value;
else
v = (unsigned long)value;
while (v || tp == tmp)
{
li = v % 10;
v = v / 10;
*tp++ = li+'0';
}
sp = str;
if (sign)
*sp++ = '-';
while (tp > tmp)
*sp++ = *--tp;
*sp = 0;
/* send the size as a 4 byte big-endian int (same as pg_sendint) */
#if BYTE_ORDER == LITTLE_ENDIAN
n32 = (uint32)((sp-str) << 24); /* We know len is < 127, so this works, replaces htonl */
#elif BYTE_ORDER == BIG_ENDIAN
n32 = (uint32) (sp-str);
#else
#error BYTE_ORDER must be BIG_ENDIAN or LITTLE_ENDIAN
#endif
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, str, strlen(str));
}
break;
case INT8OID: /* int8 */
{
char tmp[33];
char *tp = tmp;
char *sp;
uint64 v;
long li = 0;
int64 value =DatumGetInt64(attr);
bool sign = (value < 0);
if (sign)
v = -value;
else
v = (uint64)value;
while (v || tp == tmp)
{
li = v % 10;
v = v / 10;
*tp++ = li+'0';
}
sp = str;
if (sign)
*sp++ = '-';
while (tp > tmp)
*sp++ = *--tp;
*sp = 0;
#if BYTE_ORDER == LITTLE_ENDIAN
n32 = (uint32)((sp-str) << 24); /* We know len is < 127, so this works, replaces htonl */
#else
n32 = (uint32) (sp-str);
#endif
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, str, strlen(str));
}
break;
case VARCHAROID:
case TEXTOID:
case BPCHAROID:
{
const char *s;
char *p;
int len;
struct varlena *dptr;
/*
* Detoast if needed. Packed, unaligned data is OK.
* (This is a substitute for calling textout())
*/
dptr = PG_DETOAST_DATUM_PACKED(attr);
s = VARDATA_ANY(dptr);
len = VARSIZE_ANY_EXHDR(dptr);
/* inlined version of pq_sendcountedtext() */
p = pg_server_to_client(s, len);
if (p != s) /* actual conversion has been done? */
{
len = strlen(p);
n32 = htonl((uint32) len);
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, p, len);
pfree(p);
}
else
{
n32 = htonl((uint32) len);
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, s, len);
}
}
break;
default:
{
char *outputstr;
outputstr = OutputFunctionCall(&thisState->finfo, attr);
pq_sendcountedtext(buf, outputstr, strlen(outputstr), false);
}
}
}
else
{
/* Binary output */
int32 n32;
switch (fatt->atttypid)
{
case INT2OID: /* int2 */
{
short int2 = DatumGetInt16(attr);
#if BYTE_ORDER == LITTLE_ENDIAN
int2 = htons(int2);
n32 = (uint32)(2 << 24); /* replaced htonl */
#else
n32 = (uint32) 2;
#endif
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, (char *) &int2, 2);
}
break;
case INT4OID: /* int4 */
{
int32 int4 = DatumGetInt32(attr);
#if BYTE_ORDER == LITTLE_ENDIAN
int4 = htonl(int4);
n32 = (uint32)(4 << 24); /* replaced htonl */
#else
n32 = (uint32) 4;
#endif
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, (char *) &int4, 4);
}
break;
case INT8OID: /* int8 */
{
int64 int8 = DatumGetInt64(attr);
#if BYTE_ORDER == LITTLE_ENDIAN
#define local_htonll(n) ((((uint64) htonl(n)) << 32LL) | htonl((n) >> 32LL))
#define local_ntohll(n) ((((uint64) ntohl(n)) << 32LL) | (uint32) ntohl(((uint64)n) >> 32LL))
int8 = local_htonll(int8);
n32 = (uint32)(8 << 24); /* replaced htonl */
#else
n32 = (uint32) 8;
#endif
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, (char *) &int8, 8);
}
break;
case VARCHAROID:
case TEXTOID:
case BPCHAROID:
{
const char *s;
char *p;
int len;
struct varlena *dptr;
/*
* Detoast if needed. Packed, unaligned data is OK.
* (This is a substitute for calling textsend())
*/
dptr = PG_DETOAST_DATUM_PACKED(attr);
s = VARDATA_ANY(dptr);
len = VARSIZE_ANY_EXHDR(dptr);
/* inlined version of pq_sendtext(), as done by textsend() */
p = pg_server_to_client(s, len);
if (p != s) /* actual conversion has been done? */
{
len = strlen(p);
n32 = htonl((uint32) len);
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, p, len);
pfree(p);
}
else
{
n32 = htonl((uint32) len);
appendBinaryStringInfo(buf, (char *) &n32, 4);
appendBinaryStringInfo(buf, s, len);
}
}
break;
default:
{
bytea *outputbytes;
outputbytes = SendFunctionCall(&thisState->finfo, attr);
pq_sendint32(buf, VARSIZE(outputbytes) - VARHDRSZ);
pq_sendbytes(buf, VARDATA(outputbytes),
VARSIZE(outputbytes) - VARHDRSZ);
}
}
}
}
pq_endmessage_reuse(buf);
/* Return to caller's context, and flush row's temporary memory */
MemoryContextSwitchTo(oldcontext);
MemoryContextReset(myState->tmpcontext);
return true;
}
/* ----------------
* printtup_20 --- print a tuple in protocol 2.0
* ----------------
*/
static bool
printtup_20(TupleTableSlot *slot, DestReceiver *self)
{
TupleDesc typeinfo = slot->tts_tupleDescriptor;
DR_printtup *myState = (DR_printtup *) self;
MemoryContext oldcontext;
StringInfo buf = &myState->buf;
int natts = typeinfo->natts;
int i,
j,
k;
/* Set or update my derived attribute info, if needed */
if (myState->attrinfo != typeinfo || myState->nattrs != natts)
printtup_prepare_info(myState, typeinfo, natts);
/* Make sure the tuple is fully deconstructed */
slot_getallattrs(slot);
/* Switch into per-row context so we can recover memory below */
oldcontext = MemoryContextSwitchTo(myState->tmpcontext);
/*
* tell the frontend to expect new tuple data (in ASCII style)
*/
pq_beginmessage_reuse(buf, 'D');
/*
* send a bitmap of which attributes are not null
*/
j = 0;
k = 1 << 7;
for (i = 0; i < natts; ++i)
{
bool orignull;
slot_getattr(slot, i+1, &orignull);
if (!orignull)
j |= k; /* set bit if not null */
k >>= 1;
if (k == 0) /* end of byte? */
{
pq_sendint8(buf, j);
j = 0;
k = 1 << 7;
}
}
if (k != (1 << 7)) /* flush last partial byte */
pq_sendint8(buf, j);
/*
* send the attributes of this tuple
*/
for (i = 0; i < natts; ++i)
{
PrinttupAttrInfo *thisState = myState->myinfo + i;
bool isnull;
Datum attr = slot_getattr(slot, i+1, &isnull);
char *outputstr;
if (isnull)
continue;
Assert(thisState->format == 0);
outputstr = OutputFunctionCall(&thisState->finfo, attr);
pq_sendcountedtext(buf, outputstr, strlen(outputstr), true);
}
pq_endmessage_reuse(buf);
/* Return to caller's context, and flush row's temporary memory */
MemoryContextSwitchTo(oldcontext);
MemoryContextReset(myState->tmpcontext);
return true;
}
/* ----------------
* printtup_shutdown
* ----------------
*/
static void
printtup_shutdown(DestReceiver *self)
{
DR_printtup *myState = (DR_printtup *) self;
if (myState->myinfo)
pfree(myState->myinfo);
myState->myinfo = NULL;
myState->attrinfo = NULL;
if (myState->buf.data)
pfree(myState->buf.data);
myState->buf.data = NULL;
if (myState->tmpcontext)
MemoryContextDelete(myState->tmpcontext);
myState->tmpcontext = NULL;
}
/* ----------------
* printtup_destroy
* ----------------
*/
static void
printtup_destroy(DestReceiver *self)
{
pfree(self);
}
/* ----------------
* printatt
* ----------------
*/
static void
printatt(unsigned attributeId,
Form_pg_attribute attributeP,
char *value)
{
printf("\t%2d: %s%s%s%s\t(typeid = %u, len = %d, typmod = %d, byval = %c)\n",
attributeId,
NameStr(attributeP->attname),
value != NULL ? " = \"" : "",
value != NULL ? value : "",
value != NULL ? "\"" : "",
(unsigned int) (attributeP->atttypid),
attributeP->attlen,
attributeP->atttypmod,
attributeP->attbyval ? 't' : 'f');
}
/* ----------------
* debugStartup - prepare to print tuples for an interactive backend
* ----------------
*/
void
debugStartup(DestReceiver *self pg_attribute_unused(), int operation pg_attribute_unused(), TupleDesc typeinfo)
{
int natts = typeinfo->natts;
int i;
/*
* show the return type of the tuples
*/
for (i = 0; i < natts; ++i)
printatt((unsigned) i + 1, TupleDescAttr(typeinfo, i), NULL);
printf("\t----\n");
}
/* ----------------
* debugtup - print one tuple for an interactive backend
* ----------------
*/
bool
debugtup(TupleTableSlot *slot, DestReceiver *self)
{
TupleDesc typeinfo = slot->tts_tupleDescriptor;
int natts = typeinfo->natts;
int i;
Datum attr;
char *value;
bool isnull;
Oid typoutput;
bool typisvarlena;
for (i = 0; i < natts; ++i)
{
attr = slot_getattr(slot, i + 1, &isnull);
if (isnull)
continue;
getTypeOutputInfo(TupleDescAttr(typeinfo, i)->atttypid,
&typoutput, &typisvarlena);
value = OidOutputFunctionCall(typoutput, attr);
printatt((unsigned) i + 1, TupleDescAttr(typeinfo, i), value);
}
printf("\t----\n");
return true;
}
/* ----------------
* printtup_internal_20 --- print a binary tuple in protocol 2.0
*
* We use a different message type, i.e. 'B' instead of 'D' to
* indicate a tuple in internal (binary) form.
*
* This is largely same as printtup_20, except we use binary formatting.
* ----------------
*/
static bool
printtup_internal_20(TupleTableSlot *slot, DestReceiver *self)
{
TupleDesc typeinfo = slot->tts_tupleDescriptor;
DR_printtup *myState = (DR_printtup *) self;
MemoryContext oldcontext;
StringInfo buf = &myState->buf;
int natts = typeinfo->natts;
int i,
j,
k;
/* Set or update my derived attribute info, if needed */
if (myState->attrinfo != typeinfo || myState->nattrs != natts)
printtup_prepare_info(myState, typeinfo, natts);
/* Make sure the tuple is fully deconstructed */
slot_getallattrs(slot);
/* Switch into per-row context so we can recover memory below */
oldcontext = MemoryContextSwitchTo(myState->tmpcontext);
/*
* tell the frontend to expect new tuple data (in binary style)
*/
pq_beginmessage_reuse(buf, 'B');
/*
* send a bitmap of which attributes are not null
*/
j = 0;
k = 1 << 7;
for (i = 0; i < natts; ++i)
{
bool orignull;
slot_getattr(slot, i+1, &orignull);
if (!orignull)
j |= k; /* set bit if not null */
k >>= 1;
if (k == 0) /* end of byte? */
{
pq_sendint8(buf, j);
j = 0;
k = 1 << 7;
}
}
if (k != (1 << 7)) /* flush last partial byte */
pq_sendint8(buf, j);
/*
* send the attributes of this tuple
*/
for (i = 0; i < natts; ++i)
{
PrinttupAttrInfo *thisState = myState->myinfo + i;
bool isnull;
Datum attr = slot_getattr(slot, i+1, &isnull);
bytea *outputbytes;
if (isnull)
continue;
Assert(thisState->format == 1);
outputbytes = SendFunctionCall(&thisState->finfo, attr);
pq_sendint32(buf, VARSIZE(outputbytes) - VARHDRSZ);
pq_sendbytes(buf, VARDATA(outputbytes),
VARSIZE(outputbytes) - VARHDRSZ);
}
pq_endmessage_reuse(buf);
/* Return to caller's context, and flush row's temporary memory */
MemoryContextSwitchTo(oldcontext);
MemoryContextReset(myState->tmpcontext);
return true;
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
6、 golang
-
7、 openharmony