Re: 64-bit API for large object - Mailing list pgsql-hackers

From Tatsuo Ishii
Subject Re: 64-bit API for large object
Date
Msg-id 20121006.104439.915962073973074329.t-ishii@sraoss.co.jp
Whole thread Raw
In response to Re: 64-bit API for large object  (Kohei KaiGai <kaigai@kaigai.gr.jp>)
Responses Re: 64-bit API for large object  (Tatsuo Ishii <ishii@postgresql.org>)
List pgsql-hackers
As a committer, I have looked into the patch and it seems it's good to
commit. However I want to make a small enhancement in the
documentation part:

1) lo_open section needs to mention about new 64bit APIs. Also it  should include description about lo_truncate, but
thisis not 64bit  APIs author's fault since it should had been there when lo_truncate  was added.
 

2) Add mention that 64bit APIs are only available in PostgreSQL 9.3 or  later and if the API is requested against older
versionof servers  it will fail.
 

If there's no objection, I would like commit attached patches.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Hi Anzai-san,
> 
> The latest patch is fair enough for me, so let me hand over its reviewing
> for comitters.
> 
> Thanks,
> 
> 2012/10/1 Nozomi Anzai <anzai@sraoss.co.jp>:
>> Here is 64-bit API for large object version 3 patch.
>>
>>> I checked this patch. It looks good, but here are still some points to be
>>> discussed.
>>>
>>> * I have a question. What is the meaning of INT64_IS_BUSTED?
>>>   It seems to me a marker to indicate a platform without 64bit support.
>>>   However, the commit 901be0fad4034c9cf8a3588fd6cf2ece82e4b8ce
>>>   says as follows:
>>>   | Remove all the special-case code for INT64_IS_BUSTED, per decision that
>>>   | we're not going to support that anymore.
>>
>> Removed INT64_IS_BUSTED.
>>
>>
>>> * At inv_seek(), it seems to me it checks offset correctness with wrong way,
>>>   as follows:
>>> |          case SEEK_SET:
>>> |              if (offset < 0)
>>> |                  elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);
>>> |              obj_desc->offset = offset;
>>> |              break;
>>>   It is a right assumption, if large object size would be restricted to 2GB.
>>>   But the largest positive int64 is larger than expected limitation.
>>>   So, it seems to me it should be compared with (INT_MAX * PAGE_SIZE)
>>>   instead.
>>
>> Fixed.
>>
>>
>>> * At inv_write(), it definitely needs a check to prevent data-write upper 4TB.
>>>   In case when obj_desc->offset is a bit below 4TB, an additional 1GB write
>>>   will break head of the large object because of "pageno" overflow.
>>
>> Added a such check.
>>
>>
>>> * Please also add checks on inv_read() to prevent LargeObjectDesc->offset
>>>   unexpectedly overflows 4TB boundary.
>>
>> Added a such check.
>>
>>
>>> * At inv_truncate(), variable "off" is re-defined to int64. Is it really needed
>>>   change? All its usage is to store the result of "len % LOBLKSIZE".
>>
>> Fixed and back to int32.
>>
>>
>>> Thanks,
>>>
>>> 2012/9/24 Nozomi Anzai <anzai@sraoss.co.jp>:
>>> > Here is 64-bit API for large object version 2 patch.
>>> >
>>> >> I checked this patch. It can be applied onto the latest master branch
>>> >> without any problems. My comments are below.
>>> >>
>>> >> 2012/9/11 Tatsuo Ishii <ishii@postgresql.org>:
>>> >> > Ok, here is the patch to implement 64-bit API for large object, to
>>> >> > allow to use up to 4TB large objects(or 16TB if BLCKSZ changed to
>>> >> > 32KB). The patch is based on Jeremy Drake's patch posted on September
>>> >> > 23, 2005
>>> >> > (http://archives.postgresql.org/pgsql-hackers/2005-09/msg01026.php)
>>> >> > and reasonably updated/edited to adopt PostgreSQL 9.3 by Nozomi Anzai
>>> >> > for the backend part and Yugo Nagata for the rest(including
>>> >> > documentation patch).
>>> >> >
>>> >> > Here are changes made in the patch:
>>> >> >
>>> >> > 1) Frontend lo_* libpq functions(fe-lobj.c)(Yugo Nagata)
>>> >> >
>>> >> > lo_initialize() gathers backend 64-bit large object handling
>>> >> > function's oid, namely lo_lseek64, lo_tell64, lo_truncate64.
>>> >> >
>>> >> > If client calls lo_*64 functions and backend does not support them,
>>> >> > lo_*64 functions return error to caller. There might be an argument
>>> >> > since calls to lo_*64 functions can automatically be redirected to
>>> >> > 32-bit older API. I don't know this is worth the trouble though.
>>> >> >
>>> >> I think it should definitely return an error code when user tries to
>>> >> use lo_*64 functions towards the backend v9.2 or older, because
>>> >> fallback to 32bit API can raise unexpected errors if application
>>> >> intends to seek the area over than 2GB.
>>> >>
>>> >> > Currently lo_initialize() throws an error if one of oids are not
>>> >> > available. I doubt we do the same way for 64-bit functions since this
>>> >> > will make 9.3 libpq unable to access large objects stored in pre-9.2
>>> >> > PostgreSQL servers.
>>> >> >
>>> >> It seems to me the situation to split the case of pre-9.2 and post-9.3
>>> >> using a condition of "conn->sversion >= 90300".
>>> >
>>> > Fixed so, and tested it by deleteing the lo_tell64's row from pg_proc.
>>> >
>>> >
>>> >> > To pass 64-bit integer to PQfn, PQArgBlock is used like this: int *ptr
>>> >> > is a pointer to 64-bit integer and actual data is placed somewhere
>>> >> > else. There might be other way: add new member to union u to store
>>> >> > 64-bit integer:
>>> >> >
>>> >> > typedef struct
>>> >> > {
>>> >> >         int                     len;
>>> >> >         int                     isint;
>>> >> >         union
>>> >> >         {
>>> >> >                 int                *ptr;                /* can't use void (dec compiler barfs)   */
>>> >> >                 int                     integer;
>>> >> >                 int64           bigint;         /* 64-bit integer */
>>> >> >         }                       u;
>>> >> > } PQArgBlock;
>>> >> >
>>> >> > I'm a little bit worried about this way because PQArgBlock is a public
>>> >> > interface.
>>> >> >
>>> >> I'm inclined to add a new field for the union; that seems to me straight
>>> >> forward approach.
>>> >> For example, the manner in lo_seek64() seems to me confusable.
>>> >> It set 1 on "isint" field even though pointer is delivered actually.
>>> >>
>>> >> +       argv[1].isint = 1;
>>> >> +       argv[1].len = 8;
>>> >> +       argv[1].u.ptr = (int *) &len;
>>> >
>>> > Your proposal was not adopted per discussion.
>>> >
>>> >
>>> >> > Also we add new type "pg_int64":
>>> >> >
>>> >> > #ifndef NO_PG_INT64
>>> >> > #define HAVE_PG_INT64 1
>>> >> > typedef long long int pg_int64;
>>> >> > #endif
>>> >> >
>>> >> > in postgres_ext.h per suggestion from Tom Lane:
>>> >> > http://archives.postgresql.org/pgsql-hackers/2005-09/msg01062.php
>>> >> >
>>> >> I'm uncertain about context of this discussion.
>>> >>
>>> >> Does it make matter if we include <stdint.h> and use int64_t instead
>>> >> of the self defined data type?
>>> >
>>> > Your proposal was not adopted per discussion.
>>> > Per discussion, endiannness translation was moved to fe-lobj.c.
>>> >
>>> >
>>> >> > 2) Backend lo_* functions (be-fsstubs.c)(Nozomi Anzai)
>>> >> >
>>> >> > Add lo_lseek64, lo_tell64, lo_truncate64 so that they can handle
>>> >> > 64-bit seek position and data length. loread64 and lowrite64 are not
>>> >> > added because if a program tries to read/write more than 2GB at once,
>>> >> > it would be a sign that the program need to be re-designed anyway.
>>> >> >
>>> >> I think it is a reasonable.
>>> >>
>>> >> > 3) Backend inv_api.c functions(Nozomi Anzai)
>>> >> >
>>> >> > No need to add new functions. Just extend them to handle 64-bit data.
>>> >> >
>>> >> > BTW , what will happen if older 32-bit libpq accesses large objects
>>> >> > over 2GB?
>>> >> >
>>> >> > lo_read and lo_write: they can read or write lobjs using 32-bit API as
>>> >> > long as requested read/write data length is smaller than 2GB. So I
>>> >> > think we can safely allow them to access over 2GB lobjs.
>>> >> >
>>> >> > lo_lseek: again as long as requested offset is smaller than 2GB, there
>>> >> > would be no problem.
>>> >> >
>>> >> > lo_tell:if current seek position is beyond 2GB, returns an error.
>>> >> >
>>> >> Even though iteration of lo_lseek() may move the offset to 4TB, it also
>>> >> makes unavailable to use lo_tell() to obtain the current offset, so I think
>>> >> it is reasonable behavior.
>>> >>
>>> >> However, error code is not an appropriate one.
>>> >>
>>> >> +       if (INT_MAX < offset)
>>> >> +       {
>>> >> +               ereport(ERROR,
>>> >> +                               (errcode(ERRCODE_UNDEFINED_OBJECT),
>>> >> +                                errmsg("invalid large-object
>>> >> descriptor: %d", fd)));
>>> >> +               PG_RETURN_INT32(-1);
>>> >> +       }
>>> >>
>>> >> According to the manpage of lseek(2)
>>> >>     EOVERFLOW
>>> >>         The resulting file offset cannot be represented in an off_t.
>>> >>
>>> >> Please add a new error code such as ERRCODE_BLOB_OFFSET_OVERFLOW.
>>> >
>>> > Changed the error code and error message. We added a new error code
>>> > "ERRCODE_UNDEFINED_OBJECT (22P07)".
>>> >
>>> >
>>> >> > 4) src/test/examples/testlo64.c added for 64-bit API example(Yugo Nagata)
>>> >> >
>>> >> > Comments and suggestions are welcome.
>>> >> >
>>> >> miscellaneous comments are below.
>>> >>
>>> >> Regression test is helpful. Even though no need to try to create 4TB large
>>> >> object, it is helpful to write some chunks around the design boundary.
>>> >> Could you add some test cases that writes some chunks around 4TB offset.
>>> >
>>> > Added 64-bit lobj test items into regression test and confirmed it worked
>>> > rightly.
>>> >
>>> >
>>> >> Thanks,
>>> >> --
>>> >> KaiGai Kohei <kaigai@kaigai.gr.jp>
>>> >>
>>> >>
>>> >> --
>>> >> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
>>> >> To make changes to your subscription:
>>> >> http://www.postgresql.org/mailpref/pgsql-hackers
>>> >
>>> >
>>> > --
>>> > Nozomi Anzai
>>> > SRA OSS, Inc. Japan
>>> >
>>> >
>>> > --
>>> > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
>>> > To make changes to your subscription:
>>> > http://www.postgresql.org/mailpref/pgsql-hackers
>>> >
>>>
>>>
>>>
>>> --
>>> KaiGai Kohei <kaigai@kaigai.gr.jp>
>>>
>>>
>>> --
>>> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
>>> To make changes to your subscription:
>>> http://www.postgresql.org/mailpref/pgsql-hackers
>>
>>
>> --
>> Nozomi Anzai
>> SRA OSS, Inc. Japan
>>
>>
>> --
>> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
>> To make changes to your subscription:
>> http://www.postgresql.org/mailpref/pgsql-hackers
>>
> 
> 
> 
> -- 
> KaiGai Kohei <kaigai@kaigai.gr.jp>
> 
> 
> -- 
> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers
diff --git a/doc/src/sgml/lobj.sgml b/doc/src/sgml/lobj.sgml
new file mode 100644
index 291409f..d34190f
*** a/doc/src/sgml/lobj.sgml
--- b/doc/src/sgml/lobj.sgml
***************
*** 41,47 ****     larger than a single database page into a secondary storage area per table.     This makes the large
objectfacility partially obsolete.  One     remaining advantage of the large object facility is that it allows values
 
!     up to 2 GB in size, whereas <acronym>TOAST</acronym>ed fields can be at     most 1 GB.  Also, large objects can
berandomly modified using a read/write     API that is more efficient than performing such operations using
<acronym>TOAST</acronym>.
--- 41,47 ----     larger than a single database page into a secondary storage area per table.     This makes the large
objectfacility partially obsolete.  One     remaining advantage of the large object facility is that it allows values
 
!     up to 4 TB in size, whereas <acronym>TOAST</acronym>ed fields can be at     most 1 GB.  Also, large objects can
berandomly modified using a read/write     API that is more efficient than performing such operations using
<acronym>TOAST</acronym>.
*************** int lo_open(PGconn *conn, Oid lobjId, in
*** 237,243 ****      <function>lo_open</function> returns a (non-negative) large object      descriptor for later use
in<function>lo_read</function>,      <function>lo_write</function>, <function>lo_lseek</function>,
 
!      <function>lo_tell</function>, and <function>lo_close</function>.      The descriptor is only valid for      the
durationof the current transaction.      On failure, -1 is returned.
 
--- 237,245 ----      <function>lo_open</function> returns a (non-negative) large object      descriptor for later use
in<function>lo_read</function>,      <function>lo_write</function>, <function>lo_lseek</function>,
 
!      <function>lo_lseek64</function>, <function>lo_tell</function>,
!      <function>lo_tell64</function>, <function>lo_truncate</function>,
!      <function>lo_truncate64</function>, and <function>lo_close</function>.      The descriptor is only valid for
the duration of the current transaction.      On failure, -1 is returned.
 
*************** int lo_read(PGconn *conn, int fd, char *
*** 312,317 ****
--- 314,320 ----      large object descriptor, call <synopsis> int lo_lseek(PGconn *conn, int fd, int offset, int
whence);
+ pg_int64 lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence); </synopsis>
<indexterm><primary>lo_lseek</></>This function moves the      current location pointer for the large object descriptor
identifiedby
 
*************** int lo_lseek(PGconn *conn, int fd, int o
*** 321,327 ****
--- 324,339 ----      <symbol>SEEK_CUR</> (seek from current position), and      <symbol>SEEK_END</> (seek from object
end). The return value is      the new location pointer, or -1 on error.
 
+      <indexterm><primary>lo_lseek64</></> <function>lo_lseek64</function>
+      is a function for large objects larger than 2GB. <symbol>pg_int64</>
+      is defined as 8-byte integer type.
+ </para>
+ <para>
+      <function>lo_lseek64</> is new as of <productname>PostgreSQL</productname>
+      9.3; if this function is run against an older server version, it will
+      fail and return a negative value. </para>
+  </sect2>  <sect2 id="lo-tell">
*************** int lo_lseek(PGconn *conn, int fd, int o
*** 332,340 ****
--- 344,360 ----      call <synopsis> int lo_tell(PGconn *conn, int fd);
+ pg_int64 lo_tell64(PGconn *conn, int fd); </synopsis>      <indexterm><primary>lo_tell</></> If there is an error,
the     return value is negative.
 
+      <indexterm><primary>lo_tell64</></> <function>lo_tell64</function> is
+      a function for large objects larger than 2GB.
+ </para>
+ <para>
+      <function>lo_tell64</> is new as of <productname>PostgreSQL</productname>
+      9.3; if this function is run against an older server version, it will
+      fail and return a negative value. </para> </sect2> 
*************** int lo_tell(PGconn *conn, int fd);
*** 345,350 ****
--- 365,371 ----      To truncate a large object to a given length, call <synopsis> int lo_truncate(PGcon *conn, int
fd,size_t len);
 
+ int lo_truncate64(PGcon *conn, int fd, pg_int64 len); </synopsis>      <indexterm><primary>lo_truncate</></>
truncatesthe large object      descriptor <parameter>fd</> to length <parameter>len</>.  The
 
*************** int lo_truncate(PGcon *conn, int fd, siz
*** 352,357 ****
--- 373,380 ----      previous <function>lo_open</function>.  If <parameter>len</> is      greater than the current
largeobject length, the large object      is extended with null bytes ('\0').
 
+      <indexterm><primary>lo_truncate64</></> <function>lo_truncate64</function>
+      is a function for large objects larger than 2GB. </para>  <para>
*************** int lo_truncate(PGcon *conn, int fd, siz
*** 359,365 **** </para>  <para>
!      On success <function>lo_truncate</function> returns      zero.  On error, the return value is negative. </para>

--- 382,388 ---- </para>  <para>
!      On success <function>lo_truncate</function>, <function>lo_truncate64</function> returns      zero.  On error,
thereturn value is negative. </para> 
 
*************** int lo_truncate(PGcon *conn, int fd, siz
*** 368,373 ****
--- 391,401 ----      8.3; if this function is run against an older server version, it will      fail and return a
negativevalue. </para>
 
+ <para>
+      <function>lo_truncate64</> is new as of <productname>PostgreSQL</productname>
+      9.3; if this function is run against an older server version, it will
+      fail and return a negative value.
+ </para> </sect2>  <sect2 id="lo-close">
diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
new file mode 100644
index 6f7e474..4bc81ba
*** a/src/backend/libpq/be-fsstubs.c
--- b/src/backend/libpq/be-fsstubs.c
***************
*** 39,44 ****
--- 39,45 ---- #include "postgres.h"  #include <fcntl.h>
+ #include <limits.h> #include <sys/stat.h> #include <unistd.h> 
*************** lo_lseek(PG_FUNCTION_ARGS)
*** 216,222 ****     int32        fd = PG_GETARG_INT32(0);     int32        offset = PG_GETARG_INT32(1);     int32
 whence = PG_GETARG_INT32(2);
 
!     int            status;      if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)         ereport(ERROR,
--- 217,223 ----     int32        fd = PG_GETARG_INT32(0);     int32        offset = PG_GETARG_INT32(1);     int32
 whence = PG_GETARG_INT32(2);
 
!     int64        status;      if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)         ereport(ERROR,
*************** lo_lseek(PG_FUNCTION_ARGS)
*** 225,233 ****
--- 226,270 ----      status = inv_seek(cookies[fd], offset, whence); 
+     if (INT_MAX < status)
+     {
+         ereport(ERROR,
+                 (errcode(ERRCODE_BLOB_OFFSET_OVERFLOW),
+                  errmsg("offset overflow: %d", fd)));
+         PG_RETURN_INT32(-1);
+     }
+      PG_RETURN_INT32(status); } 
+ 
+ Datum
+ lo_lseek64(PG_FUNCTION_ARGS)
+ {
+     int32        fd = PG_GETARG_INT32(0);
+     int64        offset = PG_GETARG_INT64(1);
+     int32        whence = PG_GETARG_INT32(2);
+     MemoryContext currentContext;
+     int64            status;
+ 
+     if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
+     {
+         ereport(ERROR,
+                 (errcode(ERRCODE_UNDEFINED_OBJECT),
+                  errmsg("invalid large-object descriptor: %d", fd)));
+         PG_RETURN_INT64(-1);
+     }
+ 
+     Assert(fscxt != NULL);
+     currentContext = MemoryContextSwitchTo(fscxt);
+ 
+     status = inv_seek(cookies[fd], offset, whence);
+ 
+     MemoryContextSwitchTo(currentContext);
+ 
+     PG_RETURN_INT64(status);
+ }
+  Datum lo_creat(PG_FUNCTION_ARGS) {
*************** Datum
*** 264,276 **** lo_tell(PG_FUNCTION_ARGS) {     int32        fd = PG_GETARG_INT32(0);      if (fd < 0 || fd >=
cookies_size|| cookies[fd] == NULL)         ereport(ERROR,                 (errcode(ERRCODE_UNDEFINED_OBJECT),
       errmsg("invalid large-object descriptor: %d", fd))); 
 
!     PG_RETURN_INT32(inv_tell(cookies[fd])); }  Datum
--- 301,346 ---- lo_tell(PG_FUNCTION_ARGS) {     int32        fd = PG_GETARG_INT32(0);
+     int64        offset = 0;      if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)         ereport(ERROR,
           (errcode(ERRCODE_UNDEFINED_OBJECT),                  errmsg("invalid large-object descriptor: %d", fd))); 
 
!     offset = inv_tell(cookies[fd]);
! 
!     if (INT_MAX < offset)
!     {
!         ereport(ERROR,
!                 (errcode(ERRCODE_BLOB_OFFSET_OVERFLOW),
!                  errmsg("offset overflow: %d", fd)));
!         PG_RETURN_INT32(-1);
!     }
! 
!     PG_RETURN_INT32(offset);
! }
! 
! 
! Datum
! lo_tell64(PG_FUNCTION_ARGS)
! {
!     int32        fd = PG_GETARG_INT32(0);
! 
!     if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
!     {
!         ereport(ERROR,
!                 (errcode(ERRCODE_UNDEFINED_OBJECT),
!                  errmsg("invalid large-object descriptor: %d", fd)));
!         PG_RETURN_INT64(-1);
!     }
! 
!     /*
!      * We assume we do not need to switch contexts for inv_tell. That is
!      * true for now, but is probably more than this module ought to
!      * assume...
!      */
!     PG_RETURN_INT64(inv_tell(cookies[fd])); }  Datum
*************** lo_truncate(PG_FUNCTION_ARGS)
*** 533,538 ****
--- 603,635 ----     PG_RETURN_INT32(0); } 
+ Datum
+ lo_truncate64(PG_FUNCTION_ARGS)
+ {
+     int32        fd = PG_GETARG_INT32(0);
+     int64        len = PG_GETARG_INT64(1);
+ 
+     if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
+         ereport(ERROR,
+                 (errcode(ERRCODE_UNDEFINED_OBJECT),
+                  errmsg("invalid large-object descriptor: %d", fd)));
+ 
+     /* Permission checks */
+     if (!lo_compat_privileges &&
+         pg_largeobject_aclcheck_snapshot(cookies[fd]->id,
+                                          GetUserId(),
+                                          ACL_UPDATE,
+                                        cookies[fd]->snapshot) != ACLCHECK_OK)
+         ereport(ERROR,
+                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+                  errmsg("permission denied for large object %u",
+                         cookies[fd]->id)));
+ 
+     inv_truncate(cookies[fd], len);
+ 
+     PG_RETURN_INT32(0);
+ }
+  /*  * AtEOXact_LargeObject -  *         prepares large objects for transaction commit
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
new file mode 100644
index 3adfb15..3f5688b
*** a/src/backend/storage/large_object/inv_api.c
--- b/src/backend/storage/large_object/inv_api.c
*************** inv_drop(Oid lobjId)
*** 324,333 ****  * NOTE: LOs can contain gaps, just like Unix files.  We actually return  * the offset of the last
byte+ 1.  */
 
! static uint32 inv_getsize(LargeObjectDesc *obj_desc) {
!     uint32        lastbyte = 0;     ScanKeyData skey[1];     SysScanDesc sd;     HeapTuple    tuple;
--- 324,333 ----  * NOTE: LOs can contain gaps, just like Unix files.  We actually return  * the offset of the last
byte+ 1.  */
 
! static uint64 inv_getsize(LargeObjectDesc *obj_desc) {
!     uint64        lastbyte = 0;     ScanKeyData skey[1];     SysScanDesc sd;     HeapTuple    tuple;
*************** inv_getsize(LargeObjectDesc *obj_desc)
*** 368,374 ****                 heap_tuple_untoast_attr((struct varlena *) datafield);             pfreeit = true;
   }
 
!         lastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield);         if (pfreeit)
pfree(datafield);    }
 
--- 368,374 ----                 heap_tuple_untoast_attr((struct varlena *) datafield);             pfreeit = true;
   }
 
!         lastbyte = (uint64) data->pageno * LOBLKSIZE + getbytealen(datafield);         if (pfreeit)
pfree(datafield);    }
 
*************** inv_getsize(LargeObjectDesc *obj_desc)
*** 378,407 ****     return lastbyte; } 
! int
! inv_seek(LargeObjectDesc *obj_desc, int offset, int whence) {     Assert(PointerIsValid(obj_desc));      switch
(whence)    {         case SEEK_SET:
 
!             if (offset < 0)
!                 elog(ERROR, "invalid seek offset: %d", offset);             obj_desc->offset = offset;
break;        case SEEK_CUR:
 
!             if (offset < 0 && obj_desc->offset < ((uint32) (-offset)))
!                 elog(ERROR, "invalid seek offset: %d", offset);             obj_desc->offset += offset;
break;        case SEEK_END:             {
 
!                 uint32        size = inv_getsize(obj_desc); 
!                 if (offset < 0 && size < ((uint32) (-offset)))
!                     elog(ERROR, "invalid seek offset: %d", offset);
!                 obj_desc->offset = size + offset;             }             break;         default:
--- 378,408 ----     return lastbyte; } 
! int64
! inv_seek(LargeObjectDesc *obj_desc, int64 offset, int whence) {     Assert(PointerIsValid(obj_desc));      switch
(whence)    {         case SEEK_SET:
 
!             if (offset < 0 || offset >= MAX_LARGE_OBJECT_SIZE)
!                 elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);             obj_desc->offset = offset;
       break;         case SEEK_CUR:
 
!             if ((offset + obj_desc->offset) < 0 ||
!                (offset + obj_desc->offset) >= MAX_LARGE_OBJECT_SIZE)
!                 elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);             obj_desc->offset += offset;
        break;         case SEEK_END:             {
 
!                 int64        pos = inv_getsize(obj_desc) + offset; 
!                 if (pos < 0 || pos >= MAX_LARGE_OBJECT_SIZE)
!                     elog(ERROR, "invalid seek offset: " INT64_FORMAT, offset);
!                 obj_desc->offset = pos;             }             break;         default:
*************** inv_seek(LargeObjectDesc *obj_desc, int 
*** 410,416 ****     return obj_desc->offset; } 
! int inv_tell(LargeObjectDesc *obj_desc) {     Assert(PointerIsValid(obj_desc));
--- 411,417 ----     return obj_desc->offset; } 
! int64 inv_tell(LargeObjectDesc *obj_desc) {     Assert(PointerIsValid(obj_desc));
*************** int
*** 422,432 **** inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes) {     int            nread = 0;
!     int            n;
!     int            off;     int            len;     int32        pageno = (int32) (obj_desc->offset / LOBLKSIZE);
!     uint32        pageoff;     ScanKeyData skey[2];     SysScanDesc sd;     HeapTuple    tuple;
--- 423,433 ---- inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes) {     int            nread = 0;
!     int64        n;
!     int64        off;     int            len;     int32        pageno = (int32) (obj_desc->offset / LOBLKSIZE);
!     uint64        pageoff;     ScanKeyData skey[2];     SysScanDesc sd;     HeapTuple    tuple;
*************** inv_read(LargeObjectDesc *obj_desc, char
*** 437,442 ****
--- 438,446 ----     if (nbytes <= 0)         return 0; 
+     if ((nbytes + obj_desc->offset) > MAX_LARGE_OBJECT_SIZE)
+         elog(ERROR, "invalid read request size: %d", nbytes);
+      open_lo_relation();      ScanKeyInit(&skey[0],
*************** inv_read(LargeObjectDesc *obj_desc, char
*** 467,473 ****          * there may be missing pages if the LO contains unwritten "holes". We          * want missing
sectionsto read out as zeroes.          */
 
!         pageoff = ((uint32) data->pageno) * LOBLKSIZE;         if (pageoff > obj_desc->offset)         {
n= pageoff - obj_desc->offset;
 
--- 471,477 ----          * there may be missing pages if the LO contains unwritten "holes". We          * want missing
sectionsto read out as zeroes.          */
 
!         pageoff = ((uint64) data->pageno) * LOBLKSIZE;         if (pageoff > obj_desc->offset)         {
n= pageoff - obj_desc->offset;
 
*************** inv_write(LargeObjectDesc *obj_desc, con
*** 560,565 ****
--- 564,572 ----     if (nbytes <= 0)         return 0; 
+     if ((nbytes + obj_desc->offset) > MAX_LARGE_OBJECT_SIZE)
+         elog(ERROR, "invalid write request size: %d", nbytes);
+      open_lo_relation();      indstate = CatalogOpenIndexes(lo_heap_r);
*************** inv_write(LargeObjectDesc *obj_desc, con
*** 718,727 **** }  void
! inv_truncate(LargeObjectDesc *obj_desc, int len) {     int32        pageno = (int32) (len / LOBLKSIZE);
!     int            off;     ScanKeyData skey[2];     SysScanDesc sd;     HeapTuple    oldtuple;
--- 725,734 ---- }  void
! inv_truncate(LargeObjectDesc *obj_desc, int64 len) {     int32        pageno = (int32) (len / LOBLKSIZE);
!     int32        off;     ScanKeyData skey[2];     SysScanDesc sd;     HeapTuple    oldtuple;
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
new file mode 100644
index 3e04164..db8ab53
*** a/src/backend/utils/errcodes.txt
--- b/src/backend/utils/errcodes.txt
*************** Section: Class 22 - Data Exception
*** 199,204 ****
--- 199,205 ---- 2200N    E    ERRCODE_INVALID_XML_CONTENT                                    invalid_xml_content 2200S
  E    ERRCODE_INVALID_XML_COMMENT                                    invalid_xml_comment 2200T    E
ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION                    invalid_xml_processing_instruction
 
+ 22P07    E    ERRCODE_BLOB_OFFSET_OVERFLOW                                   blob_offset_overflow  Section: Class 23
-Integrity Constraint Violation 
 
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
new file mode 100644
index 77a3b41..a2da836
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
*************** DATA(insert OID = 955 (  lowrite           PGN
*** 1040,1053 ****
--- 1040,1059 ---- DESCR("large object write"); DATA(insert OID = 956 (  lo_lseek           PGNSP PGUID 12 1 0 0 0 f f
ff t f v 3 0 23 "23 23 23" _null_ _null_ _null_ _null_    lo_lseek _null_ _null_ _null_ )); DESCR("large object
seek");
+ DATA(insert OID = 3170 (  lo_lseek64           PGNSP PGUID 12 1 0 0 0 f f f f t f v 3 0 20 "23 20 23" _null_ _null_
_null__null_    lo_lseek64 _null_ _null_ _null_ ));
 
+ DESCR("large object seek (64 bit)"); DATA(insert OID = 957 (  lo_creat           PGNSP PGUID 12 1 0 0 0 f f f f t f v
10 26 "23" _null_ _null_ _null_ _null_ lo_creat _null_ _null_ _null_ )); DESCR("large object create"); DATA(insert OID
=715 (  lo_create           PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 26 "26" _null_ _null_ _null_ _null_ lo_create
_null__null_ _null_ )); DESCR("large object create"); DATA(insert OID = 958 (  lo_tell           PGNSP PGUID 12 1 0 0 0
ff f f t f v 1 0 23 "23" _null_ _null_ _null_ _null_ lo_tell _null_ _null_ _null_ )); DESCR("large object position");
 
+ DATA(insert OID = 3171 (  lo_tell64           PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 20 "23" _null_ _null_ _null_
_null_lo_tell64 _null_ _null_ _null_ ));
 
+ DESCR("large object position (64 bit)"); DATA(insert OID = 1004 (  lo_truncate       PGNSP PGUID 12 1 0 0 0 f f f f t
fv 2 0 23 "23 23" _null_ _null_ _null_ _null_ lo_truncate _null_ _null_ _null_ )); DESCR("truncate large object");
 
+ DATA(insert OID = 3172 (  lo_truncate64       PGNSP PGUID 12 1 0 0 0 f f f f t f v 2 0 23 "23 20" _null_ _null_
_null__null_ lo_truncate64 _null_ _null_ _null_ ));
 
+ DESCR("truncate large object (64 bit)");  DATA(insert OID = 959 (  on_pl               PGNSP PGUID 12 1 0 0 0 f f f f
tf i 2 0 16 "600 628" _null_ _null_ _null_ _null_    on_pl _null_ _null_ _null_ )); DATA(insert OID = 960 (  on_sl
        PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 16 "601 628" _null_ _null_ _null_ _null_    on_sl _null_ _null_ _null_
));
diff --git a/src/include/libpq/be-fsstubs.h b/src/include/libpq/be-fsstubs.h
new file mode 100644
index 0c832da..d74ea0e
*** a/src/include/libpq/be-fsstubs.h
--- b/src/include/libpq/be-fsstubs.h
*************** extern Datum lowrite(PG_FUNCTION_ARGS);
*** 34,41 ****
--- 34,44 ----  extern Datum lo_lseek(PG_FUNCTION_ARGS); extern Datum lo_tell(PG_FUNCTION_ARGS);
+ extern Datum lo_lseek64(PG_FUNCTION_ARGS);
+ extern Datum lo_tell64(PG_FUNCTION_ARGS); extern Datum lo_unlink(PG_FUNCTION_ARGS); extern Datum
lo_truncate(PG_FUNCTION_ARGS);
+ extern Datum lo_truncate64(PG_FUNCTION_ARGS);  /*  * compatibility option for access control
diff --git a/src/include/postgres_ext.h b/src/include/postgres_ext.h
new file mode 100644
index b6ebb7a..76502de
*** a/src/include/postgres_ext.h
--- b/src/include/postgres_ext.h
*************** typedef unsigned int Oid;
*** 56,59 ****
--- 56,64 ---- #define PG_DIAG_SOURCE_LINE        'L' #define PG_DIAG_SOURCE_FUNCTION 'R' 
+ #ifndef NO_PG_INT64
+ #define HAVE_PG_INT64 1
+ typedef long long int pg_int64;
+ #endif
+  #endif
diff --git a/src/include/storage/large_object.h b/src/include/storage/large_object.h
new file mode 100644
index 1fe07ee..52f01c6
*** a/src/include/storage/large_object.h
--- b/src/include/storage/large_object.h
*************** typedef struct LargeObjectDesc
*** 37,43 ****     Oid            id;                /* LO's identifier */     Snapshot    snapshot;        /* snapshot
touse */     SubTransactionId subid;        /* owning subtransaction ID */
 
!     uint32        offset;            /* current seek pointer */     int            flags;            /* locking info,
etc*/  /* flag bits: */
 
--- 37,43 ----     Oid            id;                /* LO's identifier */     Snapshot    snapshot;        /* snapshot
touse */     SubTransactionId subid;        /* owning subtransaction ID */
 
!     uint64        offset;            /* current seek pointer */     int            flags;            /* locking info,
etc*/  /* flag bits: */
 
*************** typedef struct LargeObjectDesc
*** 62,68 ****  * This avoids unnecessary tuple updates caused by partial-page writes.  */ #define LOBLKSIZE
(BLCKSZ/ 4)
 
!   /*  * Function definitions...
--- 62,71 ----  * This avoids unnecessary tuple updates caused by partial-page writes.  */ #define LOBLKSIZE
(BLCKSZ/ 4)
 
! /*
!  * Maximum byte length for each large object
! */
! #define MAX_LARGE_OBJECT_SIZE    INT64CONST(INT_MAX * LOBLKSIZE)  /*  * Function definitions...
*************** extern Oid    inv_create(Oid lobjId);
*** 74,83 **** extern LargeObjectDesc *inv_open(Oid lobjId, int flags, MemoryContext mcxt); extern void
inv_close(LargeObjectDesc*obj_desc); extern int    inv_drop(Oid lobjId);
 
! extern int    inv_seek(LargeObjectDesc *obj_desc, int offset, int whence);
! extern int    inv_tell(LargeObjectDesc *obj_desc); extern int    inv_read(LargeObjectDesc *obj_desc, char *buf, int
nbytes);extern int    inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes);
 
! extern void inv_truncate(LargeObjectDesc *obj_desc, int len);  #endif   /* LARGE_OBJECT_H */
--- 77,86 ---- extern LargeObjectDesc *inv_open(Oid lobjId, int flags, MemoryContext mcxt); extern void
inv_close(LargeObjectDesc*obj_desc); extern int    inv_drop(Oid lobjId);
 
! extern int64    inv_seek(LargeObjectDesc *obj_desc, int64 offset, int whence);
! extern int64    inv_tell(LargeObjectDesc *obj_desc); extern int    inv_read(LargeObjectDesc *obj_desc, char *buf, int
nbytes);extern int    inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes);
 
! extern void inv_truncate(LargeObjectDesc *obj_desc, int64 len);  #endif   /* LARGE_OBJECT_H */
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
new file mode 100644
index 9d95e26..56d0bb8
*** a/src/interfaces/libpq/exports.txt
--- b/src/interfaces/libpq/exports.txt
*************** PQping                    158
*** 161,163 ****
--- 161,166 ---- PQpingParams              159 PQlibVersion              160 PQsetSingleRowMode        161
+ lo_lseek64                162
+ lo_tell64                 163
+ lo_truncate64             164
diff --git a/src/interfaces/libpq/fe-lobj.c b/src/interfaces/libpq/fe-lobj.c
new file mode 100644
index f3a6d03..fb17ac8
*** a/src/interfaces/libpq/fe-lobj.c
--- b/src/interfaces/libpq/fe-lobj.c
***************
*** 37,46 ****
--- 37,52 ---- #include "libpq-int.h" #include "libpq/libpq-fs.h"        /* must come after sys/stat.h */ 
+ /* for ntohl/htonl */
+ #include <netinet/in.h>
+ #include <arpa/inet.h>
+  #define LO_BUFSIZE          8192  static int    lo_initialize(PGconn *conn); static Oid    lo_import_internal(PGconn
*conn,const char *filename, Oid oid);
 
+ static pg_int64    lo_hton64(pg_int64 host64);
+ static pg_int64    lo_ntoh64(pg_int64 net64);  /*  * lo_open
*************** lo_truncate(PGconn *conn, int fd, size_t
*** 174,179 ****
--- 180,238 ----     } } 
+ /*
+  * lo_truncate64
+  *      truncates an existing large object to the given size
+  *
+  * returns 0 upon success
+  * returns -1 upon failure
+  */
+ #ifdef HAVE_PG_INT64
+ int
+ lo_truncate64(PGconn *conn, int fd, pg_int64 len)
+ {
+     PQArgBlock    argv[2];
+     PGresult   *res;
+     int            retval;
+     int            result_len;
+ 
+     if (conn == NULL || conn->lobjfuncs == NULL)
+     {
+         if (lo_initialize(conn) < 0)
+             return -1;
+     }
+ 
+     if (conn->lobjfuncs->fn_lo_truncate64 == 0)
+     {
+         printfPQExpBuffer(&conn->errorMessage,
+             libpq_gettext("cannot determine OID of function lo_truncate64\n"));
+         return -1;
+     }
+ 
+     argv[0].isint = 1;
+     argv[0].len = 4;
+     argv[0].u.integer = fd;
+ 
+     len = lo_hton64(len);
+     argv[1].isint = 0;
+     argv[1].len = 8;
+     argv[1].u.ptr = (int *) &len;
+ 
+     res = PQfn(conn, conn->lobjfuncs->fn_lo_truncate64,
+                &retval, &result_len, 1, argv, 2);
+ 
+     if (PQresultStatus(res) == PGRES_COMMAND_OK)
+     {
+         PQclear(res);
+         return retval;
+     }
+     else
+     {
+         PQclear(res);
+         return -1;
+     }
+ }
+ #endif  /*  * lo_read
*************** lo_lseek(PGconn *conn, int fd, int offse
*** 311,316 ****
--- 370,432 ---- }  /*
+  * lo_lseek64
+  *      change the current read or write location on a large object
+  * currently, only L_SET is a legal value for whence
+  *
+  */
+ 
+ #ifdef HAVE_PG_INT64
+ pg_int64
+ lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence)
+ {
+     PQArgBlock    argv[3];
+     PGresult   *res;
+     pg_int64        retval;
+     int            result_len;
+ 
+     if (conn == NULL || conn->lobjfuncs == NULL)
+     {
+         if (lo_initialize(conn) < 0)
+             return -1;
+     }
+ 
+     if (conn->lobjfuncs->fn_lo_lseek64 == 0)
+     {
+         printfPQExpBuffer(&conn->errorMessage,
+             libpq_gettext("cannot determine OID of function lo_lseek64\n"));
+         return -1;
+     }
+ 
+     argv[0].isint = 1;
+     argv[0].len = 4;
+     argv[0].u.integer = fd;
+ 
+     offset = lo_hton64(offset);
+     argv[1].isint = 0;
+     argv[1].len = 8;
+     argv[1].u.ptr = (int *) &offset;
+ 
+     argv[2].isint = 1;
+     argv[2].len = 4;
+     argv[2].u.integer = whence;
+ 
+     res = PQfn(conn, conn->lobjfuncs->fn_lo_lseek64,
+                (int *)&retval, &result_len, 0, argv, 3);
+     if (PQresultStatus(res) == PGRES_COMMAND_OK)
+     {
+         PQclear(res);
+         return lo_ntoh64((pg_int64)retval);
+     }
+     else
+     {
+         PQclear(res);
+         return -1;
+     }
+ }
+ #endif
+ 
+ /*  * lo_creat  *      create a new large object  * the mode is ignored (once upon a time it had a use)
*************** lo_tell(PGconn *conn, int fd)
*** 436,441 ****
--- 552,603 ---- }  /*
+  * lo_tell64
+  *      returns the current seek location of the large object
+  *
+  */
+ #ifdef HAVE_PG_INT64
+ pg_int64
+ lo_tell64(PGconn *conn, int fd)
+ {
+     pg_int64    retval;
+     PQArgBlock    argv[1];
+     PGresult   *res;
+     int            result_len;
+ 
+     if (conn == NULL || conn->lobjfuncs == NULL)
+     {
+         if (lo_initialize(conn) < 0)
+             return -1;
+     }
+ 
+     if (conn->lobjfuncs->fn_lo_tell64 == 0)
+     {
+         printfPQExpBuffer(&conn->errorMessage,
+             libpq_gettext("cannot determine OID of function lo_tell64\n"));
+         return -1;
+     }
+ 
+     argv[0].isint = 1;
+     argv[0].len = 4;
+     argv[0].u.integer = fd;
+ 
+     res = PQfn(conn, conn->lobjfuncs->fn_lo_tell64,
+                (int *) &retval, &result_len, 0, argv, 1);
+     if (PQresultStatus(res) == PGRES_COMMAND_OK)
+     {
+         PQclear(res);
+         return lo_ntoh64((pg_int64) retval);
+     }
+     else
+     {
+         PQclear(res);
+         return -1;
+     }
+ }
+ #endif
+ 
+ /*  * lo_unlink  *      delete a file  *
*************** lo_initialize(PGconn *conn)
*** 713,720 ****
--- 875,885 ----             "'lo_create', "             "'lo_unlink', "             "'lo_lseek', "
+             "'lo_lseek64', "             "'lo_tell', "
+             "'lo_tell64', "             "'lo_truncate', "
+             "'lo_truncate64', "             "'loread', "             "'lowrite') "             "and pronamespace =
(selectoid from pg_catalog.pg_namespace "
 
*************** lo_initialize(PGconn *conn)
*** 765,774 ****
--- 930,945 ----             lobjfuncs->fn_lo_unlink = foid;         else if (strcmp(fname, "lo_lseek") == 0)
 lobjfuncs->fn_lo_lseek = foid;
 
+         else if (strcmp(fname, "lo_lseek64") == 0)
+             lobjfuncs->fn_lo_lseek64 = foid;         else if (strcmp(fname, "lo_tell") == 0)
lobjfuncs->fn_lo_tell= foid;
 
+         else if (strcmp(fname, "lo_tell64") == 0)
+             lobjfuncs->fn_lo_tell64 = foid;         else if (strcmp(fname, "lo_truncate") == 0)
lobjfuncs->fn_lo_truncate= foid;
 
+         else if (strcmp(fname, "lo_truncate64") == 0)
+             lobjfuncs->fn_lo_truncate64 = foid;         else if (strcmp(fname, "loread") == 0)
lobjfuncs->fn_lo_read= foid;         else if (strcmp(fname, "lowrite") == 0)
 
*************** lo_initialize(PGconn *conn)
*** 836,845 ****         free(lobjfuncs);         return -1;     }
!      /*      * Put the structure into the connection control      */     conn->lobjfuncs = lobjfuncs;     return 0;
}
--- 1007,1082 ----         free(lobjfuncs);         return -1;     }
!     if (conn->sversion >= 90300)
!     {
!         if (lobjfuncs->fn_lo_lseek64 == 0)
!         {
!             printfPQExpBuffer(&conn->errorMessage,
!                     libpq_gettext("cannot determine OID of function lo_lseek64\n"));
!             free(lobjfuncs);
!             return -1;
!         }
!         if (lobjfuncs->fn_lo_tell64 == 0)
!         {
!             printfPQExpBuffer(&conn->errorMessage,
!                     libpq_gettext("cannot determine OID of function lo_tell64\n"));
!             free(lobjfuncs);
!             return -1;
!         }
!         if (lobjfuncs->fn_lo_truncate64 == 0)
!         {
!             printfPQExpBuffer(&conn->errorMessage,
!                     libpq_gettext("cannot determine OID of function lo_truncate64\n"));
!             free(lobjfuncs);
!             return -1;
!         }
!     }     /*      * Put the structure into the connection control      */     conn->lobjfuncs = lobjfuncs;     return
0;}
 
+ 
+ /*
+  * lo_hton64
+  *      converts an 64-bit integer from host byte order to network byte order
+  */
+ static pg_int64
+ lo_hton64(pg_int64 host64)
+ {
+     pg_int64     result;
+     uint32_t    h32, l32;
+ 
+     /* High order half first, since we're doing MSB-first */
+     h32 = (uint32_t) (host64 >> 32);
+ 
+     /* Now the low order half */
+     l32 = (uint32_t) (host64 & 0xffffffff);
+ 
+     result = htonl(l32);
+     result <<= 32;
+     result |= htonl(h32);
+ 
+     return result;
+ }
+ 
+ /*
+  * lo_ntoh64
+  *      converts an 64-bit integer from network byte order to host byte order
+  */
+ static pg_int64
+ lo_ntoh64(pg_int64 net64)
+ {
+     pg_int64     result;
+     uint32_t    h32, l32;
+ 
+     l32 = (uint32_t) (net64 >> 32);
+     h32 = (uint32_t) (net64 & 0xffffffff);
+ 
+     result = ntohl(h32);
+     result <<= 32;
+     result |= ntohl(l32);
+ 
+     return result;
+ }
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
new file mode 100644
index 9d05dd2..73568ca
*** a/src/interfaces/libpq/libpq-fe.h
--- b/src/interfaces/libpq/libpq-fe.h
*************** extern Oid    lo_import(PGconn *conn, const
*** 548,553 ****
--- 548,559 ---- extern Oid    lo_import_with_oid(PGconn *conn, const char *filename, Oid lobjId); extern int
lo_export(PGconn*conn, Oid lobjId, const char *filename); 
 
+ #ifdef HAVE_PG_INT64
+ extern pg_int64    lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence);
+ extern pg_int64    lo_tell64(PGconn *conn, int fd);
+ extern int    lo_truncate64(PGconn *conn, int fd, pg_int64 len);
+ #endif
+  /* === in fe-misc.c === */  /* Get the version of the libpq library in use */
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
new file mode 100644
index 4a6c8fe..375821e
*** a/src/interfaces/libpq/libpq-int.h
--- b/src/interfaces/libpq/libpq-int.h
*************** typedef struct pgLobjfuncs
*** 271,278 ****
--- 271,281 ----     Oid            fn_lo_create;    /* OID of backend function lo_create    */     Oid
fn_lo_unlink;   /* OID of backend function lo_unlink    */     Oid            fn_lo_lseek;    /* OID of backend
functionlo_lseek        */
 
+     Oid            fn_lo_lseek64;    /* OID of backend function lo_lseek64        */     Oid            fn_lo_tell;
    /* OID of backend function lo_tell        */
 
+     Oid            fn_lo_tell64;        /* OID of backend function lo_tell64        */     Oid
fn_lo_truncate;/* OID of backend function lo_truncate    */
 
+     Oid            fn_lo_truncate64; /* OID of backend function lo_truncate64    */     Oid            fn_lo_read;
   /* OID of backend function LOread        */     Oid            fn_lo_write;    /* OID of backend function LOwrite
   */ } PGlobjfuncs;
 
diff --git a/src/test/examples/Makefile b/src/test/examples/Makefile
new file mode 100644
index bbc6ee1..aee5c04
*** a/src/test/examples/Makefile
--- b/src/test/examples/Makefile
*************** override CPPFLAGS := -I$(libpq_srcdir) $
*** 14,20 **** override LDLIBS := $(libpq_pgport) $(LDLIBS)  
! PROGS = testlibpq testlibpq2 testlibpq3 testlibpq4 testlo  all: $(PROGS) 
--- 14,20 ---- override LDLIBS := $(libpq_pgport) $(LDLIBS)  
! PROGS = testlibpq testlibpq2 testlibpq3 testlibpq4 testlo testlo64  all: $(PROGS) 
diff --git a/src/test/regress/input/largeobject.source b/src/test/regress/input/largeobject.source
new file mode 100644
index 40f40f8..4984d78
*** a/src/test/regress/input/largeobject.source
--- b/src/test/regress/input/largeobject.source
*************** SELECT lo_tell(fd) FROM lotest_stash_val
*** 125,130 ****
--- 125,153 ---- SELECT lo_close(fd) FROM lotest_stash_values; END; 
+ -- Test 64-bit largelbject functions.
+ BEGIN;
+ UPDATE lotest_stash_values SET fd = lo_open(loid, CAST(x'20000' | x'40000' AS integer));
+ 
+ SELECT lo_lseek64(fd, 4294967296, 0) FROM lotest_stash_values;
+ SELECT lowrite(fd, 'offset:4GB') FROM lotest_stash_values;
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+ 
+ SELECT lo_lseek64(fd, -10, 1) FROM lotest_stash_values;
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+ SELECT loread(fd, 10) FROM lotest_stash_values;
+ 
+ SELECT lo_truncate64(fd, 5000000000) FROM lotest_stash_values;
+ SELECT lo_lseek64(fd, 0, 2) FROM lotest_stash_values;
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+ 
+ SELECT lo_truncate64(fd, 3000000000) FROM lotest_stash_values;
+ SELECT lo_lseek64(fd, 0, 2) FROM lotest_stash_values;
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+ 
+ SELECT lo_close(fd) FROM lotest_stash_values;
+ END;
+  -- lo_unlink(lobjId oid) returns integer -- return value appears to always be 1 SELECT lo_unlink(loid) from
lotest_stash_values;
diff --git a/src/test/regress/output/largeobject.source b/src/test/regress/output/largeobject.source
new file mode 100644
index 55aaf8f..74c4772
*** a/src/test/regress/output/largeobject.source
--- b/src/test/regress/output/largeobject.source
*************** SELECT lo_close(fd) FROM lotest_stash_va
*** 210,215 ****
--- 210,297 ---- (1 row)  END;
+ -- Test 64-bit largelbject functions.
+ BEGIN;
+ UPDATE lotest_stash_values SET fd = lo_open(loid, CAST(x'20000' | x'40000' AS integer));
+ SELECT lo_lseek64(fd, 4294967296, 0) FROM lotest_stash_values;
+  lo_lseek64 
+ ------------
+  4294967296
+ (1 row)
+ 
+ SELECT lowrite(fd, 'offset:4GB') FROM lotest_stash_values;
+  lowrite 
+ ---------
+       10
+ (1 row)
+ 
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+  lo_tell64  
+ ------------
+  4294967306
+ (1 row)
+ 
+ SELECT lo_lseek64(fd, -10, 1) FROM lotest_stash_values;
+  lo_lseek64 
+ ------------
+  4294967296
+ (1 row)
+ 
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+  lo_tell64  
+ ------------
+  4294967296
+ (1 row)
+ 
+ SELECT loread(fd, 10) FROM lotest_stash_values;
+    loread   
+ ------------
+  offset:4GB
+ (1 row)
+ 
+ SELECT lo_truncate64(fd, 5000000000) FROM lotest_stash_values;
+  lo_truncate64 
+ ---------------
+              0
+ (1 row)
+ 
+ SELECT lo_lseek64(fd, 0, 2) FROM lotest_stash_values;
+  lo_lseek64 
+ ------------
+  5000000000
+ (1 row)
+ 
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+  lo_tell64  
+ ------------
+  5000000000
+ (1 row)
+ 
+ SELECT lo_truncate64(fd, 3000000000) FROM lotest_stash_values;
+  lo_truncate64 
+ ---------------
+              0
+ (1 row)
+ 
+ SELECT lo_lseek64(fd, 0, 2) FROM lotest_stash_values;
+  lo_lseek64 
+ ------------
+  3000000000
+ (1 row)
+ 
+ SELECT lo_tell64(fd) FROM lotest_stash_values;
+  lo_tell64  
+ ------------
+  3000000000
+ (1 row)
+ 
+ SELECT lo_close(fd) FROM lotest_stash_values;
+  lo_close 
+ ----------
+         0
+ (1 row)
+ 
+ END; -- lo_unlink(lobjId oid) returns integer -- return value appears to always be 1 SELECT lo_unlink(loid) from
lotest_stash_values;

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