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Major overhaul of large-object implementation, by Denis Perchine with

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kibitzing from Tom Lane.  Large objects are now all stored in a single
system relation "pg_largeobject" --- no more xinv or xinx files, no more
relkind 'l'.  This should offer substantial performance improvement for
large numbers of LOs, since there won't be directory bloat anymore.
It'll also fix problems like running out of locktable space when you
access thousands of LOs in one transaction.
Also clean up cruft in read/write routines.  LOs with "holes" in them
(never-written byte ranges) now work just like Unix files with holes do:
a hole reads as zeroes but doesn't occupy storage space.
INITDB forced!
This commit is contained in:
Tom Lane
2000-10-24 01:38:44 +00:00
parent d7186cfa9b
commit 4f44aa04b5
21 changed files with 735 additions and 1205 deletions
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52
src/include/storage/large_object.h
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@@ -8,39 +8,54 @@
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: large_object.h,v 1.17 2000/10/22 05:27:23 momjian Exp $
* $Id: large_object.h,v 1.18 2000/10/24 01:38:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef LARGE_OBJECT_H
#define LARGE_OBJECT_H
#include <sys/types.h>
#include "utils/rel.h"
#include "access/relscan.h"
/*
* This structure will eventually have lots more stuff associated with it.
/*----------
* Data about a currently-open large object.
*
* id is the logical OID of the large object
* offset is the current seek offset within the LO
* heap_r holds an open-relation reference to pg_largeobject
* index_r holds an open-relation reference to pg_largeobject_loid_pn_index
*
* NOTE: before 7.1, heap_r and index_r held references to the separate
* table and index of a specific large object. Now they all live in one rel.
*----------
*/
typedef struct LargeObjectDesc
{
Relation heap_r; /* heap relation */
Relation index_r; /* index relation on seqno attribute */
IndexScanDesc iscan; /* index scan we're using */
TupleDesc hdesc; /* heap relation tuple desc */
TupleDesc idesc; /* index relation tuple desc */
uint32 lowbyte; /* low byte on the current page */
uint32 highbyte; /* high byte on the current page */
typedef struct LargeObjectDesc {
Oid id;
uint32 offset; /* current seek pointer */
ItemPointerData htid; /* tid of current heap tuple */
int flags; /* locking info, etc */
/* flag bits: */
#define IFS_RDLOCK (1 << 0)
#define IFS_WRLOCK (1 << 1)
#define IFS_ATEOF (1 << 2)
u_long flags; /* locking info, etc */
Relation heap_r;
Relation index_r;
} LargeObjectDesc;
/*
* Each "page" (tuple) of a large object can hold this much data
*
* Calculation is max tuple size less tuple header, loid field (Oid),
* pageno field (int32), and varlena header of data (int32). Note we
* assume none of the fields will be NULL, hence no need for null bitmap.
*/
#define LOBLKSIZE (MaxTupleSize \
- MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) \
- sizeof(Oid) - sizeof(int32) * 2)
/*
* Function definitions...
*/
@@ -55,7 +70,4 @@ 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, char *buf, int nbytes);
/* added for buffer leak prevention [ PA ] */
extern void inv_cleanindex(LargeObjectDesc *obj_desc);
#endif /* LARGE_OBJECT_H */