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db3c4c3a2d
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.
97 lines
3.7 KiB
C
97 lines
3.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* hashjoin.h
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* internal structures for hash joins
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*
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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* $Id: hashjoin.h,v 1.15 1999/10/13 15:02:26 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef HASHJOIN_H
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#define HASHJOIN_H
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#include "access/htup.h"
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#include "storage/buffile.h"
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/* ----------------------------------------------------------------
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* hash-join hash table structures
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*
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* Each active hashjoin has a HashJoinTable control block which is
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* palloc'd in the executor's context. All other storage needed for
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* the hashjoin is kept in a private "named portal", one for each hashjoin.
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* This makes it easy and fast to release the storage when we don't need it
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* anymore.
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*
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* The portal manager guarantees that portals will be discarded at end of
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* transaction, so we have no problem with a memory leak if the join is
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* aborted early by an error. (Likewise, any temporary files we make will
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* be cleaned up by the virtual file manager in event of an error.)
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*
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* Storage that should live through the entire join is allocated from the
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* portal's "variable context", while storage that is only wanted for the
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* current batch is allocated in the portal's "heap context". By popping
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* the portal's heap at the end of a batch, we free all the per-batch storage
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* reliably and without tedium.
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* ----------------------------------------------------------------
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*/
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typedef struct HashJoinTupleData
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{
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struct HashJoinTupleData *next; /* link to next tuple in same
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* bucket */
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HeapTupleData htup; /* tuple header */
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} HashJoinTupleData;
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typedef HashJoinTupleData *HashJoinTuple;
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typedef struct HashTableData
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{
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int nbuckets; /* buckets in use during this batch */
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int totalbuckets; /* total number of (virtual) buckets */
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HashJoinTuple *buckets; /* buckets[i] is head of list of tuples */
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/* buckets array is per-batch storage, as are all the tuples */
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int nbatch; /* number of batches; 0 means 1-pass join */
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int curbatch; /* current batch #, or 0 during 1st pass */
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/*
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* all these arrays are allocated for the life of the hash join, but
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* only if nbatch > 0:
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*/
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BufFile **innerBatchFile; /* buffered virtual temp file per batch */
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BufFile **outerBatchFile; /* buffered virtual temp file per batch */
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long *outerBatchSize; /* count of tuples in each outer batch
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* file */
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long *innerBatchSize; /* count of tuples in each inner batch
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* file */
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/*
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* During 1st scan of inner relation, we get tuples from executor. If
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* nbatch > 0 then tuples that don't belong in first nbuckets logical
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* buckets get dumped into inner-batch temp files. The same statements
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* apply for the 1st scan of the outer relation, except we write
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* tuples to outer-batch temp files. If nbatch > 0 then we do the
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* following for each batch: 1. Read tuples from inner batch file,
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* load into hash buckets. 2. Read tuples from outer batch file, match
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* to hash buckets and output.
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*/
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/*
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* Ugly kluge: myPortal ought to be declared as type Portal (ie,
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* PortalD*) but if we try to include utils/portal.h here, we end up
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* with a circular dependency of include files! Until the various
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* node.h files are restructured in a cleaner way, we have to fake it.
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* The most reliable fake seems to be to declare myPortal as void *
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* and then cast it to the right things in nodeHash.c.
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*/
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void *myPortal; /* where to keep working storage */
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MemoryContext hashCxt; /* context for whole-hash-join storage */
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MemoryContext batchCxt; /* context for this-batch-only storage */
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} HashTableData;
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typedef HashTableData *HashJoinTable;
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#endif /* HASHJOIN_H */
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