Provide a build-time option to store large relations as single files, rather

than dividing them into 1GB segments as has been our longtime practice.  This
requires working support for large files in the operating system; at least for
the time being, it won't be the default.

Zdenek Kotala

1 files changed, 20 insertions, 21 deletions

diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 8d79e9574b8..94e5c67911a 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/file/buffile.c,v 1.29 2008/01/01 19:45:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/file/buffile.c,v 1.30 2008/03/10 20:06:27 tgl Exp $
  *
  * NOTES:
  *
@@ -38,13 +38,12 @@
 #include "storage/buffile.h"
 
 /*
- * The maximum safe file size is presumed to be RELSEG_SIZE * BLCKSZ.
- * Note we adhere to this limit whether or not LET_OS_MANAGE_FILESIZE
- * is defined, although md.c ignores it when that symbol is defined.
- * The reason for doing this is that we'd like large temporary BufFiles
- * to be spread across multiple tablespaces when available.
+ * We break BufFiles into gigabyte-sized segments, whether or not
+ * USE_SEGMENTED_FILES is defined.  The reason is that we'd like large
+ * temporary BufFiles to be spread across multiple tablespaces when available.
  */
-#define MAX_PHYSICAL_FILESIZE  (RELSEG_SIZE * BLCKSZ)
+#define MAX_PHYSICAL_FILESIZE	0x40000000
+#define BUFFILE_SEG_SIZE		(MAX_PHYSICAL_FILESIZE / BLCKSZ)
 
 /*
  * This data structure represents a buffered file that consists of one or
@@ -56,7 +55,7 @@ struct BufFile
 	int			numFiles;		/* number of physical files in set */
 	/* all files except the last have length exactly MAX_PHYSICAL_FILESIZE */
 	File	   *files;			/* palloc'd array with numFiles entries */
-	long	   *offsets;		/* palloc'd array with numFiles entries */
+	off_t	   *offsets;		/* palloc'd array with numFiles entries */
 
 	/*
 	 * offsets[i] is the current seek position of files[i].  We use this to
@@ -72,7 +71,7 @@ struct BufFile
 	 * Position as seen by user of BufFile is (curFile, curOffset + pos).
 	 */
 	int			curFile;		/* file index (0..n) part of current pos */
-	int			curOffset;		/* offset part of current pos */
+	off_t		curOffset;		/* offset part of current pos */
 	int			pos;			/* next read/write position in buffer */
 	int			nbytes;			/* total # of valid bytes in buffer */
 	char		buffer[BLCKSZ];
@@ -97,7 +96,7 @@ makeBufFile(File firstfile)
 	file->numFiles = 1;
 	file->files = (File *) palloc(sizeof(File));
 	file->files[0] = firstfile;
-	file->offsets = (long *) palloc(sizeof(long));
+	file->offsets = (off_t *) palloc(sizeof(off_t));
 	file->offsets[0] = 0L;
 	file->isTemp = false;
 	file->isInterXact = false;
@@ -124,8 +123,8 @@ extendBufFile(BufFile *file)
 
 	file->files = (File *) repalloc(file->files,
 									(file->numFiles + 1) * sizeof(File));
-	file->offsets = (long *) repalloc(file->offsets,
-									  (file->numFiles + 1) * sizeof(long));
+	file->offsets = (off_t *) repalloc(file->offsets,
+									  (file->numFiles + 1) * sizeof(off_t));
 	file->files[file->numFiles] = pfile;
 	file->offsets[file->numFiles] = 0L;
 	file->numFiles++;
@@ -279,9 +278,9 @@ BufFileDumpBuffer(BufFile *file)
 		bytestowrite = file->nbytes - wpos;
 		if (file->isTemp)
 		{
-			long		availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset;
+			off_t		availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset;
 
-			if ((long) bytestowrite > availbytes)
+			if ((off_t) bytestowrite > availbytes)
 				bytestowrite = (int) availbytes;
 		}
 
@@ -451,10 +450,10 @@ BufFileFlush(BufFile *file)
  * impossible seek is attempted.
  */
 int
-BufFileSeek(BufFile *file, int fileno, long offset, int whence)
+BufFileSeek(BufFile *file, int fileno, off_t offset, int whence)
 {
 	int			newFile;
-	long		newOffset;
+	off_t		newOffset;
 
 	switch (whence)
 	{
@@ -469,7 +468,7 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
 			/*
 			 * Relative seek considers only the signed offset, ignoring
 			 * fileno. Note that large offsets (> 1 gig) risk overflow in this
-			 * add...
+			 * add, unless we have 64-bit off_t.
 			 */
 			newFile = file->curFile;
 			newOffset = (file->curOffset + file->pos) + offset;
@@ -537,7 +536,7 @@ BufFileSeek(BufFile *file, int fileno, long offset, int whence)
 }
 
 void
-BufFileTell(BufFile *file, int *fileno, long *offset)
+BufFileTell(BufFile *file, int *fileno, off_t *offset)
 {
 	*fileno = file->curFile;
 	*offset = file->curOffset + file->pos;
@@ -558,8 +557,8 @@ int
 BufFileSeekBlock(BufFile *file, long blknum)
 {
 	return BufFileSeek(file,
-					   (int) (blknum / RELSEG_SIZE),
-					   (blknum % RELSEG_SIZE) * BLCKSZ,
+					   (int) (blknum / BUFFILE_SEG_SIZE),
+					   (off_t) (blknum % BUFFILE_SEG_SIZE) * BLCKSZ,
 					   SEEK_SET);
 }
 
@@ -575,7 +574,7 @@ BufFileTellBlock(BufFile *file)
 	long		blknum;
 
 	blknum = (file->curOffset + file->pos) / BLCKSZ;
-	blknum += file->curFile * RELSEG_SIZE;
+	blknum += file->curFile * BUFFILE_SEG_SIZE;
 	return blknum;
 }