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for each temp file, rather than once per sort or hashjoin; this allows spreading the data of a large sort or join across multiple tablespaces. (I remain dubious that this will make any difference in practice, but certain people insisted.) Arrange to cache the results of parsing the GUC variable instead of recomputing from scratch on every demand, and push usage of the cache down to the bottommost fd.c level.
46 lines
1.7 KiB
C
46 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* buffile.h
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* Management of large buffered files, primarily temporary files.
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*
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* The BufFile routines provide a partial replacement for stdio atop
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* virtual file descriptors managed by fd.c. Currently they only support
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* buffered access to a virtual file, without any of stdio's formatting
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* features. That's enough for immediate needs, but the set of facilities
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* could be expanded if necessary.
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*
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* BufFile also supports working with temporary files that exceed the OS
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* file size limit and/or the largest offset representable in an int.
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* It might be better to split that out as a separately accessible module,
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* but currently we have no need for oversize temp files without buffered
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* access.
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*
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* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/buffile.h,v 1.22 2007/06/07 19:19:57 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef BUFFILE_H
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#define BUFFILE_H
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/* BufFile is an opaque type whose details are not known outside buffile.c. */
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typedef struct BufFile BufFile;
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/*
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* prototypes for functions in buffile.c
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*/
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extern BufFile *BufFileCreateTemp(bool interXact);
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extern void BufFileClose(BufFile *file);
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extern size_t BufFileRead(BufFile *file, void *ptr, size_t size);
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extern size_t BufFileWrite(BufFile *file, void *ptr, size_t size);
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extern int BufFileSeek(BufFile *file, int fileno, long offset, int whence);
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extern void BufFileTell(BufFile *file, int *fileno, long *offset);
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extern int BufFileSeekBlock(BufFile *file, long blknum);
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#endif /* BUFFILE_H */
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