database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-11 10:01:57 +03:00
Code Activity

Split 'BufFile' routines out of fd.c into a new module, buffile.c. Extend

Browse Source 
BufFile so that it handles multi-segment temporary files transparently.
This allows sorts and hashes to work with data exceeding 2Gig (or whatever
the local limit on file size is).  Change psort.c to use relative seeks
instead of absolute seeks for backwards scanning, so that it won't fail
when the data volume exceeds 2Gig.
This commit is contained in:
Tom Lane
1999-10-13 15:02:32 +00:00
parent c3ac9f07b7
commit db3c4c3a2d
12 changed files with 707 additions and 318 deletions
Download Patch File Download Diff File Expand all files Collapse all files

112
src/backend/utils/sort/psort.c
View File

@ -4,7 +4,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: psort.c,v 1.56 1999/07/17 20:18:16 momjian Exp $
* $Id: psort.c,v 1.57 1999/10/13 15:02:31 tgl Exp $
*
* NOTES
* Sorts the first relation into the second relation.
@ -142,7 +142,8 @@ psort_begin(Sort *node, int nkeys, ScanKey key)
PS(node)->psort_grab_file = mergeruns(node);
PS(node)->psort_current = 0;
PS(node)->psort_saved = 0;
PS(node)->psort_saved_fileno = 0;
PS(node)->psort_saved = 0L;
return true;
}
@ -227,7 +228,7 @@ inittapes(Sort *node)
#define SETTUPLEN(TUP, LEN) ((TUP)->t_len = (LEN) - HEAPTUPLESIZE)
#define rewind(FP) BufFileSeek(FP, 0L, SEEK_SET)
#define rewind(FP) BufFileSeek(FP, 0, 0L, SEEK_SET)
/*
* USEMEM - record use of memory FREEMEM - record
@ -764,9 +765,6 @@ psort_grabtuple(Sort *node, bool *should_free)
tup = ALLOCTUP(tuplen);
SETTUPLEN(tup, tuplen);
GETTUP(node, tup, tuplen, PS(node)->psort_grab_file);
/* Update current merged sort file position */
PS(node)->psort_current += tuplen + sizeof(tlendummy);
return tup;
}
else
@ -775,70 +773,67 @@ psort_grabtuple(Sort *node, bool *should_free)
return NULL;
}
}
/* Backward */
if (PS(node)->psort_current <= sizeof(tlendummy))
return NULL;
/*
/* Backward.
*
* if all tuples are fetched already then we return last tuple,
* else - tuple before last returned.
*/
if (PS(node)->all_fetched)
{
/*
* psort_current is pointing to the zero tuplen at the end of
* file
* Assume seek position is pointing just past the zero tuplen
* at the end of file; back up and fetch last tuple's ending
* length word. If seek fails we must have a completely empty
* file.
*/
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_current - sizeof(tlendummy), SEEK_SET);
if (BufFileSeek(PS(node)->psort_grab_file, 0,
- (long) (2 * sizeof(tlendummy)), SEEK_CUR))
return NULL;
GETLEN(tuplen, PS(node)->psort_grab_file);
if (PS(node)->psort_current < tuplen)
elog(ERROR, "psort_grabtuple: too big last tuple len in backward scan");
PS(node)->all_fetched = false;
}
else
{
/* move to position of end tlen of prev tuple */
PS(node)->psort_current -= sizeof(tlendummy);
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_current, SEEK_SET);
GETLEN(tuplen, PS(node)->psort_grab_file); /* get tlen of prev
* tuple */
/*
* Back up and fetch prev tuple's ending length word.
* If seek fails, assume we are at start of file.
*/
if (BufFileSeek(PS(node)->psort_grab_file, 0,
- (long) sizeof(tlendummy), SEEK_CUR))
return NULL;
GETLEN(tuplen, PS(node)->psort_grab_file);
if (tuplen == 0)
elog(ERROR, "psort_grabtuple: tuplen is 0 in backward scan");
if (PS(node)->psort_current <= tuplen + sizeof(tlendummy))
{ /* prev tuple should be first one */
if (PS(node)->psort_current != tuplen)
elog(ERROR, "psort_grabtuple: first tuple expected in backward scan");
PS(node)->psort_current = 0;
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_current, SEEK_SET);
/*
* Back up to get ending length word of tuple before it.
*/
if (BufFileSeek(PS(node)->psort_grab_file, 0,
- (long) (tuplen + 2*sizeof(tlendummy)), SEEK_CUR))
{
/* If fail, presumably the prev tuple is the first in the file.
* Back up so that it becomes next to read in forward direction
* (not obviously right, but that is what in-memory case does)
*/
if (BufFileSeek(PS(node)->psort_grab_file, 0,
- (long) (tuplen + sizeof(tlendummy)), SEEK_CUR))
elog(ERROR, "psort_grabtuple: too big last tuple len in backward scan");
return NULL;
}
/*
* Get position of prev tuple. This tuple becomes current
* tuple now and we have to return previous one.
*/
PS(node)->psort_current -= tuplen;
/* move to position of end tlen of prev tuple */
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_current - sizeof(tlendummy), SEEK_SET);
GETLEN(tuplen, PS(node)->psort_grab_file);
if (PS(node)->psort_current < tuplen + sizeof(tlendummy))
elog(ERROR, "psort_grabtuple: too big tuple len in backward scan");
}
/*
* move to prev (or last) tuple start position + sizeof(t_len)
* Now we have the length of the prior tuple, back up and read it.
* Note: GETTUP expects we are positioned after the initial length
* word of the tuple, so back up to that point.
*/
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_current - tuplen, SEEK_SET);
if (BufFileSeek(PS(node)->psort_grab_file, 0,
- (long) tuplen, SEEK_CUR))
elog(ERROR, "psort_grabtuple: too big tuple len in backward scan");
tup = ALLOCTUP(tuplen);
SETTUPLEN(tup, tuplen);
GETTUP(node, tup, tuplen, PS(node)->psort_grab_file);
return tup; /* file position is equal to psort_current */
return tup;
}
else
{
@ -875,6 +870,8 @@ psort_grabtuple(Sort *node, bool *should_free)
/*
* psort_markpos - saves current position in the merged sort file
*
* XXX I suspect these need to save & restore the all_fetched flag as well!
*/
void
psort_markpos(Sort *node)
@ -882,7 +879,12 @@ psort_markpos(Sort *node)
Assert(node != (Sort *) NULL);
Assert(PS(node) != (Psortstate *) NULL);
PS(node)->psort_saved = PS(node)->psort_current;
if (PS(node)->using_tape_files == true)
BufFileTell(PS(node)->psort_grab_file,
& PS(node)->psort_saved_fileno,
& PS(node)->psort_saved);
else
PS(node)->psort_saved = PS(node)->psort_current;
}
/*
@ -897,8 +899,11 @@ psort_restorepos(Sort *node)
if (PS(node)->using_tape_files == true)
BufFileSeek(PS(node)->psort_grab_file,
PS(node)->psort_saved, SEEK_SET);
PS(node)->psort_current = PS(node)->psort_saved;
PS(node)->psort_saved_fileno,
PS(node)->psort_saved,
SEEK_SET);
else
PS(node)->psort_current = PS(node)->psort_saved;
}
/*
@ -952,7 +957,8 @@ psort_rescan(Sort *node)
{
PS(node)->all_fetched = false;
PS(node)->psort_current = 0;
PS(node)->psort_saved = 0;
PS(node)->psort_saved_fileno = 0;
PS(node)->psort_saved = 0L;
if (PS(node)->using_tape_files == true)
rewind(PS(node)->psort_grab_file);
}
@ -973,11 +979,7 @@ psort_rescan(Sort *node)
static BufFile *
gettape()
{
File tfile;
tfile = OpenTemporaryFile();
Assert(tfile >= 0);
return BufFileCreate(tfile);
return BufFileCreateTemp();
}
/*