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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2000-11-02 23:52:06 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2000-11-02 23:52:06 +0000 |
| commit | 94d8bbe5fbf18199d5aa968ba36749312453fd48 (patch) | |
| tree | fca4ec4ef66211b1741055dc169171575f43a9eb /src/backend | |
| parent | db263da46879cbcbaaaf20cfb676a2f748098de3 (diff) | |
| download | postgresql-94d8bbe5fbf18199d5aa968ba36749312453fd48.tar.gz postgresql-94d8bbe5fbf18199d5aa968ba36749312453fd48.zip | |
Improve inv_getsize() per suggestion from Denis Perchine; also fix
thinkos in inv_seek().
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/storage/large_object/inv_api.c | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c index 607c4861dc5..2c8e855dda2 100644 --- a/src/backend/storage/large_object/inv_api.c +++ b/src/backend/storage/large_object/inv_api.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.79 2000/10/24 01:38:29 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.80 2000/11/02 23:52:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -186,7 +186,6 @@ inv_getsize(LargeObjectDesc *obj_desc) { bool found = false; uint32 lastbyte = 0; - uint32 thislastbyte; ScanKeyData skey[1]; IndexScanDesc sd; RetrieveIndexResult indexRes; @@ -209,7 +208,13 @@ inv_getsize(LargeObjectDesc *obj_desc) tuple.t_datamcxt = CurrentMemoryContext; tuple.t_data = NULL; - while ((indexRes = index_getnext(sd, ForwardScanDirection))) + /* + * Because the pg_largeobject index is on both loid and pageno, + * but we constrain only loid, a backwards scan should visit all + * pages of the large object in reverse pageno order. So, it's + * sufficient to examine the first valid tuple (== last valid page). + */ + while ((indexRes = index_getnext(sd, BackwardScanDirection))) { tuple.t_self = indexRes->heap_iptr; heap_fetch(obj_desc->heap_r, SnapshotNow, &tuple, &buffer); @@ -226,12 +231,11 @@ inv_getsize(LargeObjectDesc *obj_desc) heap_tuple_untoast_attr((varattrib *) datafield); pfreeit = true; } - thislastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield); - if (thislastbyte > lastbyte) - lastbyte = thislastbyte; + lastbyte = data->pageno * LOBLKSIZE + getbytealen(datafield); if (pfreeit) pfree(datafield); ReleaseBuffer(buffer); + break; } index_endscan(sd); @@ -254,16 +258,17 @@ inv_seek(LargeObjectDesc *obj_desc, int offset, int whence) obj_desc->offset = offset; break; case SEEK_CUR: - if ((obj_desc->offset + offset) < 0) + if (offset < 0 && obj_desc->offset < ((uint32) (- offset))) elog(ERROR, "inv_seek: invalid offset: %d", offset); obj_desc->offset += offset; break; case SEEK_END: { - uint32 size = inv_getsize(obj_desc); - if (offset < 0 || ((uint32) offset) > size) - elog(ERROR, "inv_seek: invalid offset"); - obj_desc->offset = size - offset; + uint32 size = inv_getsize(obj_desc); + + if (offset < 0 && size < ((uint32) (- offset))) + elog(ERROR, "inv_seek: invalid offset: %d", offset); + obj_desc->offset = size + offset; } break; default: |