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Adjust lo_open() so that specifying INV_READ without INV_WRITE creates

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a descriptor that uses the current transaction snapshot, rather than
SnapshotNow as it did before (and still does if INV_WRITE is set).
This means pg_dump will now dump a consistent snapshot of large object
contents, as it never could do before.  Also, add a lo_create() function
that is similar to lo_creat() but allows the desired OID of the large
object to be specified.  This will simplify pg_restore considerably
(but I'll fix that in a separate commit).
This commit is contained in:
Tom Lane
2005-06-13 02:26:53 +00:00
parent f52a34229b
commit a2fb7b8a1f
11 changed files with 265 additions and 96 deletions
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46
src/backend/libpq/be-fsstubs.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.77 2004/12/31 21:59:50 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.78 2005/06/13 02:26:48 tgl Exp $
*
* NOTES
* This should be moved to a more appropriate place. It is here
@@ -195,6 +195,12 @@ lo_write(int fd, char *buf, int len)
return -1;
}
if ((cookies[fd]->flags & IFS_WRLOCK) == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("large object descriptor %d was not opened for writing",
fd)));
Assert(fscxt != NULL);
currentContext = MemoryContextSwitchTo(fscxt);
@@ -236,26 +242,33 @@ lo_lseek(PG_FUNCTION_ARGS)
Datum
lo_creat(PG_FUNCTION_ARGS)
{
int32 mode = PG_GETARG_INT32(0);
LargeObjectDesc *lobjDesc;
MemoryContext currentContext;
Oid lobjId;
MemoryContext currentContext;
/* do we actually need fscxt for this? */
CreateFSContext();
currentContext = MemoryContextSwitchTo(fscxt);
lobjDesc = inv_create(mode);
lobjId = inv_create(InvalidOid);
if (lobjDesc == NULL)
{
MemoryContextSwitchTo(currentContext);
PG_RETURN_OID(InvalidOid);
}
MemoryContextSwitchTo(currentContext);
lobjId = lobjDesc->id;
PG_RETURN_OID(lobjId);
}
inv_close(lobjDesc);
Datum
lo_create(PG_FUNCTION_ARGS)
{
Oid lobjId = PG_GETARG_OID(0);
MemoryContext currentContext;
/* do we actually need fscxt for this? */
CreateFSContext();
currentContext = MemoryContextSwitchTo(fscxt);
lobjId = inv_create(lobjId);
MemoryContextSwitchTo(currentContext);
@@ -403,12 +416,13 @@ lo_import(PG_FUNCTION_ARGS)
/*
* create an inversion object
*/
lobj = inv_create(INV_READ | INV_WRITE);
lobjOid = lobj->id;
lobjOid = inv_create(InvalidOid);
/*
* read in from the filesystem and write to the inversion file
* read in from the filesystem and write to the inversion object
*/
lobj = inv_open(lobjOid, INV_WRITE);
while ((nbytes = FileRead(fd, buf, BUFSIZE)) > 0)
{
tmp = inv_write(lobj, buf, nbytes);
@@ -421,8 +435,8 @@ lo_import(PG_FUNCTION_ARGS)
errmsg("could not read server file \"%s\": %m",
fnamebuf)));
FileClose(fd);
inv_close(lobj);
FileClose(fd);
PG_RETURN_OID(lobjOid);
}