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77a7e9968b
to make a reasonable attempt at accounting for palloc overhead, not just the requested size of each memory chunk. Since in many scenarios this will make for a significant reduction in the amount of space acquired, partially compensate by doubling the default value of SORT_MEM to 1Mb. Per discussion in pgsql-general around 9-Jun-2002..
2182 lines
65 KiB
C
2182 lines
65 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuplesort.c
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* Generalized tuple sorting routines.
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*
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* This module handles sorting of heap tuples, index tuples, or single
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* Datums (and could easily support other kinds of sortable objects,
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* if necessary). It works efficiently for both small and large amounts
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* of data. Small amounts are sorted in-memory using qsort(). Large
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* amounts are sorted using temporary files and a standard external sort
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* algorithm.
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*
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* See Knuth, volume 3, for more than you want to know about the external
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* sorting algorithm. We divide the input into sorted runs using replacement
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* selection, in the form of a priority tree implemented as a heap
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* (essentially his Algorithm 5.2.3H), then merge the runs using polyphase
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* merge, Knuth's Algorithm 5.4.2D. The logical "tapes" used by Algorithm D
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* are implemented by logtape.c, which avoids space wastage by recycling
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* disk space as soon as each block is read from its "tape".
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*
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* We do not form the initial runs using Knuth's recommended replacement
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* selection data structure (Algorithm 5.4.1R), because it uses a fixed
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* number of records in memory at all times. Since we are dealing with
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* tuples that may vary considerably in size, we want to be able to vary
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* the number of records kept in memory to ensure full utilization of the
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* allowed sort memory space. So, we keep the tuples in a variable-size
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* heap, with the next record to go out at the top of the heap. Like
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* Algorithm 5.4.1R, each record is stored with the run number that it
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* must go into, and we use (run number, key) as the ordering key for the
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* heap. When the run number at the top of the heap changes, we know that
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* no more records of the prior run are left in the heap.
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*
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* The (approximate) amount of memory allowed for any one sort operation
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* is given in kilobytes by the external variable SortMem. Initially,
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* we absorb tuples and simply store them in an unsorted array as long as
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* we haven't exceeded SortMem. If we reach the end of the input without
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* exceeding SortMem, we sort the array using qsort() and subsequently return
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* tuples just by scanning the tuple array sequentially. If we do exceed
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* SortMem, we construct a heap using Algorithm H and begin to emit tuples
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* into sorted runs in temporary tapes, emitting just enough tuples at each
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* step to get back within the SortMem limit. Whenever the run number at
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* the top of the heap changes, we begin a new run with a new output tape
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* (selected per Algorithm D). After the end of the input is reached,
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* we dump out remaining tuples in memory into a final run (or two),
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* then merge the runs using Algorithm D.
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*
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* When merging runs, we use a heap containing just the frontmost tuple from
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* each source run; we repeatedly output the smallest tuple and insert the
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* next tuple from its source tape (if any). When the heap empties, the merge
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* is complete. The basic merge algorithm thus needs very little memory ---
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* only M tuples for an M-way merge, and M is at most six in the present code.
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* However, we can still make good use of our full SortMem allocation by
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* pre-reading additional tuples from each source tape. Without prereading,
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* our access pattern to the temporary file would be very erratic; on average
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* we'd read one block from each of M source tapes during the same time that
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* we're writing M blocks to the output tape, so there is no sequentiality of
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* access at all, defeating the read-ahead methods used by most Unix kernels.
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* Worse, the output tape gets written into a very random sequence of blocks
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* of the temp file, ensuring that things will be even worse when it comes
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* time to read that tape. A straightforward merge pass thus ends up doing a
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* lot of waiting for disk seeks. We can improve matters by prereading from
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* each source tape sequentially, loading about SortMem/M bytes from each tape
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* in turn. Then we run the merge algorithm, writing but not reading until
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* one of the preloaded tuple series runs out. Then we switch back to preread
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* mode, fill memory again, and repeat. This approach helps to localize both
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* read and write accesses.
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*
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* When the caller requests random access to the sort result, we form
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* the final sorted run on a logical tape which is then "frozen", so
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* that we can access it randomly. When the caller does not need random
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* access, we return from tuplesort_performsort() as soon as we are down
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* to one run per logical tape. The final merge is then performed
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* on-the-fly as the caller repeatedly calls tuplesort_gettuple; this
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* saves one cycle of writing all the data out to disk and reading it in.
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*
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*
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* Portions Copyright (c) 1996-2002, 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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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/sort/tuplesort.c,v 1.25 2002/08/12 00:36:12 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "access/nbtree.h"
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#include "catalog/catname.h"
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#include "catalog/pg_amop.h"
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#include "catalog/pg_amproc.h"
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#include "catalog/pg_operator.h"
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#include "miscadmin.h"
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#include "utils/fmgroids.h"
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#include "utils/logtape.h"
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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#include "utils/tuplesort.h"
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/*
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* Possible states of a Tuplesort object. These denote the states that
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* persist between calls of Tuplesort routines.
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*/
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typedef enum
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{
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TSS_INITIAL, /* Loading tuples; still within memory
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* limit */
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TSS_BUILDRUNS, /* Loading tuples; writing to tape */
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TSS_SORTEDINMEM, /* Sort completed entirely in memory */
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TSS_SORTEDONTAPE, /* Sort completed, final run is on tape */
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TSS_FINALMERGE /* Performing final merge on-the-fly */
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} TupSortStatus;
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/*
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* We use a seven-tape polyphase merge, which is the "sweet spot" on the
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* tapes-to-passes curve according to Knuth's figure 70 (section 5.4.2).
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*/
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#define MAXTAPES 7 /* Knuth's T */
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#define TAPERANGE (MAXTAPES-1) /* Knuth's P */
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/*
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* Private state of a Tuplesort operation.
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*/
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struct Tuplesortstate
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{
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TupSortStatus status; /* enumerated value as shown above */
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bool randomAccess; /* did caller request random access? */
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long availMem; /* remaining memory available, in bytes */
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LogicalTapeSet *tapeset; /* logtape.c object for tapes in a temp
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* file */
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/*
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* These function pointers decouple the routines that must know what
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* kind of tuple we are sorting from the routines that don't need to
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* know it. They are set up by the tuplesort_begin_xxx routines.
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*
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* Function to compare two tuples; result is per qsort() convention, ie:
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*
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* <0, 0, >0 according as a<b, a=b, a>b.
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*/
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int (*comparetup) (Tuplesortstate *state, const void *a, const void *b);
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/*
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* Function to copy a supplied input tuple into palloc'd space. (NB:
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* we assume that a single pfree() is enough to release the tuple
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* later, so the representation must be "flat" in one palloc chunk.)
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* state->availMem must be decreased by the amount of space used.
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*/
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void *(*copytup) (Tuplesortstate *state, void *tup);
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/*
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* Function to write a stored tuple onto tape. The representation of
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* the tuple on tape need not be the same as it is in memory;
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* requirements on the tape representation are given below. After
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* writing the tuple, pfree() it, and increase state->availMem by the
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* amount of memory space thereby released.
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*/
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void (*writetup) (Tuplesortstate *state, int tapenum, void *tup);
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/*
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* Function to read a stored tuple from tape back into memory. 'len'
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* is the already-read length of the stored tuple. Create and return
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* a palloc'd copy, and decrease state->availMem by the amount of
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* memory space consumed.
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*/
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void *(*readtup) (Tuplesortstate *state, int tapenum, unsigned int len);
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/*
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* This array holds pointers to tuples in sort memory. If we are in
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* state INITIAL, the tuples are in no particular order; if we are in
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* state SORTEDINMEM, the tuples are in final sorted order; in states
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* BUILDRUNS and FINALMERGE, the tuples are organized in "heap" order
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* per Algorithm H. (Note that memtupcount only counts the tuples
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* that are part of the heap --- during merge passes, memtuples[]
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* entries beyond TAPERANGE are never in the heap and are used to hold
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* pre-read tuples.) In state SORTEDONTAPE, the array is not used.
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*/
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void **memtuples; /* array of pointers to palloc'd tuples */
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int memtupcount; /* number of tuples currently present */
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int memtupsize; /* allocated length of memtuples array */
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/*
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* While building initial runs, this array holds the run number for
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* each tuple in memtuples[]. During merge passes, we re-use it to
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* hold the input tape number that each tuple in the heap was read
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* from, or to hold the index of the next tuple pre-read from the same
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* tape in the case of pre-read entries. This array is never
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* allocated unless we need to use tapes. Whenever it is allocated,
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* it has the same length as memtuples[].
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*/
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int *memtupindex; /* index value associated with
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* memtuples[i] */
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/*
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* While building initial runs, this is the current output run number
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* (starting at 0). Afterwards, it is the number of initial runs we
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* made.
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*/
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int currentRun;
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/*
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* These variables are only used during merge passes. mergeactive[i]
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* is true if we are reading an input run from (actual) tape number i
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* and have not yet exhausted that run. mergenext[i] is the memtuples
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* index of the next pre-read tuple (next to be loaded into the heap)
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* for tape i, or 0 if we are out of pre-read tuples. mergelast[i]
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* similarly points to the last pre-read tuple from each tape.
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* mergeavailmem[i] is the amount of unused space allocated for tape
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* i. mergefreelist and mergefirstfree keep track of unused locations
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* in the memtuples[] array. memtupindex[] links together pre-read
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* tuples for each tape as well as recycled locations in
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* mergefreelist. It is OK to use 0 as a null link in these lists,
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* because memtuples[0] is part of the merge heap and is never a
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* pre-read tuple.
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*/
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bool mergeactive[MAXTAPES]; /* Active input run source? */
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int mergenext[MAXTAPES]; /* first preread tuple for each
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* source */
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int mergelast[MAXTAPES]; /* last preread tuple for each
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* source */
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long mergeavailmem[MAXTAPES]; /* availMem for prereading
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* tapes */
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long spacePerTape; /* actual per-tape target usage */
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int mergefreelist; /* head of freelist of recycled slots */
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int mergefirstfree; /* first slot never used in this merge */
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/*
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* Variables for Algorithm D. Note that destTape is a "logical" tape
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* number, ie, an index into the tp_xxx[] arrays. Be careful to keep
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* "logical" and "actual" tape numbers straight!
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*/
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int Level; /* Knuth's l */
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int destTape; /* current output tape (Knuth's j, less 1) */
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int tp_fib[MAXTAPES]; /* Target Fibonacci run counts
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* (A[]) */
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int tp_runs[MAXTAPES]; /* # of real runs on each tape */
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int tp_dummy[MAXTAPES]; /* # of dummy runs for each tape
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* (D[]) */
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int tp_tapenum[MAXTAPES]; /* Actual tape numbers (TAPE[]) */
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/*
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* These variables are used after completion of sorting to keep track
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* of the next tuple to return. (In the tape case, the tape's current
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* read position is also critical state.)
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*/
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int result_tape; /* actual tape number of finished output */
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int current; /* array index (only used if SORTEDINMEM) */
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bool eof_reached; /* reached EOF (needed for cursors) */
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/* markpos_xxx holds marked position for mark and restore */
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long markpos_block; /* tape block# (only used if SORTEDONTAPE) */
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int markpos_offset; /* saved "current", or offset in tape
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* block */
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bool markpos_eof; /* saved "eof_reached" */
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/*
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* These variables are specific to the HeapTuple case; they are set by
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* tuplesort_begin_heap and used only by the HeapTuple routines.
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*/
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TupleDesc tupDesc;
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int nKeys;
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ScanKey scanKeys;
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SortFunctionKind *sortFnKinds;
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/*
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* These variables are specific to the IndexTuple case; they are set
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* by tuplesort_begin_index and used only by the IndexTuple routines.
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*/
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Relation indexRel;
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ScanKey indexScanKey;
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bool enforceUnique; /* complain if we find duplicate tuples */
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/*
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* These variables are specific to the Datum case; they are set by
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* tuplesort_begin_datum and used only by the DatumTuple routines.
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*/
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Oid datumType;
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Oid sortOperator;
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FmgrInfo sortOpFn; /* cached lookup data for sortOperator */
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SortFunctionKind sortFnKind;
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/* we need typelen and byval in order to know how to copy the Datums. */
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int datumTypeLen;
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bool datumTypeByVal;
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};
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#define COMPARETUP(state,a,b) ((*(state)->comparetup) (state, a, b))
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#define COPYTUP(state,tup) ((*(state)->copytup) (state, tup))
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#define WRITETUP(state,tape,tup) ((*(state)->writetup) (state, tape, tup))
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#define READTUP(state,tape,len) ((*(state)->readtup) (state, tape, len))
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#define LACKMEM(state) ((state)->availMem < 0)
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#define USEMEM(state,amt) ((state)->availMem -= (amt))
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#define FREEMEM(state,amt) ((state)->availMem += (amt))
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/*--------------------
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*
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* NOTES about on-tape representation of tuples:
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*
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* We require the first "unsigned int" of a stored tuple to be the total size
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* on-tape of the tuple, including itself (so it is never zero; an all-zero
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* unsigned int is used to delimit runs). The remainder of the stored tuple
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* may or may not match the in-memory representation of the tuple ---
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* any conversion needed is the job of the writetup and readtup routines.
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*
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* If state->randomAccess is true, then the stored representation of the
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* tuple must be followed by another "unsigned int" that is a copy of the
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* length --- so the total tape space used is actually sizeof(unsigned int)
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* more than the stored length value. This allows read-backwards. When
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* randomAccess is not true, the write/read routines may omit the extra
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* length word.
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*
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* writetup is expected to write both length words as well as the tuple
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* data. When readtup is called, the tape is positioned just after the
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* front length word; readtup must read the tuple data and advance past
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* the back length word (if present).
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*
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* The write/read routines can make use of the tuple description data
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* stored in the Tuplesortstate record, if needed. They are also expected
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* to adjust state->availMem by the amount of memory space (not tape space!)
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* released or consumed. There is no error return from either writetup
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* or readtup; they should elog() on failure.
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*
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*
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* NOTES about memory consumption calculations:
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*
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* We count space allocated for tuples against the SortMem limit, plus
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* the space used by the variable-size arrays memtuples and memtupindex.
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* Fixed-size space (primarily the LogicalTapeSet I/O buffers) is not
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* counted.
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*
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* Note that we count actual space used (as shown by GetMemoryChunkSpace)
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* rather than the originally-requested size. This is important since
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* palloc can add substantial overhead. It's not a complete answer since
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* we won't count any wasted space in palloc allocation blocks, but it's
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* a lot better than what we were doing before 7.3.
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*
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*--------------------
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*/
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/*
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* For sorting single Datums, we build "pseudo tuples" that just carry
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* the datum's value and null flag. For pass-by-reference data types,
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* the actual data value appears after the DatumTupleHeader (MAXALIGNed,
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* of course), and the value field in the header is just a pointer to it.
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*/
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typedef struct
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{
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Datum val;
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bool isNull;
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} DatumTuple;
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static Tuplesortstate *tuplesort_begin_common(bool randomAccess);
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static void puttuple_common(Tuplesortstate *state, void *tuple);
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static void inittapes(Tuplesortstate *state);
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static void selectnewtape(Tuplesortstate *state);
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static void mergeruns(Tuplesortstate *state);
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static void mergeonerun(Tuplesortstate *state);
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static void beginmerge(Tuplesortstate *state);
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static void mergepreread(Tuplesortstate *state);
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static void dumptuples(Tuplesortstate *state, bool alltuples);
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static void tuplesort_heap_insert(Tuplesortstate *state, void *tuple,
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int tupleindex, bool checkIndex);
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static void tuplesort_heap_siftup(Tuplesortstate *state, bool checkIndex);
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static unsigned int getlen(Tuplesortstate *state, int tapenum, bool eofOK);
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static void markrunend(Tuplesortstate *state, int tapenum);
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static int qsort_comparetup(const void *a, const void *b);
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static int comparetup_heap(Tuplesortstate *state,
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const void *a, const void *b);
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static void *copytup_heap(Tuplesortstate *state, void *tup);
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static void writetup_heap(Tuplesortstate *state, int tapenum, void *tup);
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static void *readtup_heap(Tuplesortstate *state, int tapenum,
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unsigned int len);
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static int comparetup_index(Tuplesortstate *state,
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const void *a, const void *b);
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static void *copytup_index(Tuplesortstate *state, void *tup);
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static void writetup_index(Tuplesortstate *state, int tapenum, void *tup);
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static void *readtup_index(Tuplesortstate *state, int tapenum,
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unsigned int len);
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static int comparetup_datum(Tuplesortstate *state,
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const void *a, const void *b);
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static void *copytup_datum(Tuplesortstate *state, void *tup);
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static void writetup_datum(Tuplesortstate *state, int tapenum, void *tup);
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static void *readtup_datum(Tuplesortstate *state, int tapenum,
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unsigned int len);
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/*
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* Since qsort(3) will not pass any context info to qsort_comparetup(),
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* we have to use this ugly static variable. It is set to point to the
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* active Tuplesortstate object just before calling qsort. It should
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* not be used directly by anything except qsort_comparetup().
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*/
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static Tuplesortstate *qsort_tuplesortstate;
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/*
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* tuplesort_begin_xxx
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*
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* Initialize for a tuple sort operation.
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*
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* After calling tuplesort_begin, the caller should call tuplesort_puttuple
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* zero or more times, then call tuplesort_performsort when all the tuples
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* have been supplied. After performsort, retrieve the tuples in sorted
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* order by calling tuplesort_gettuple until it returns NULL. (If random
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* access was requested, rescan, markpos, and restorepos can also be called.)
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* For Datum sorts, putdatum/getdatum are used instead of puttuple/gettuple.
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* Call tuplesort_end to terminate the operation and release memory/disk space.
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*/
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static Tuplesortstate *
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tuplesort_begin_common(bool randomAccess)
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{
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Tuplesortstate *state;
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state = (Tuplesortstate *) palloc(sizeof(Tuplesortstate));
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MemSet((char *) state, 0, sizeof(Tuplesortstate));
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|
|
state->status = TSS_INITIAL;
|
|
state->randomAccess = randomAccess;
|
|
state->availMem = SortMem * 1024L;
|
|
state->tapeset = NULL;
|
|
|
|
state->memtupcount = 0;
|
|
state->memtupsize = 1024; /* initial guess */
|
|
state->memtuples = (void **) palloc(state->memtupsize * sizeof(void *));
|
|
|
|
state->memtupindex = NULL; /* until and unless needed */
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
|
|
state->currentRun = 0;
|
|
|
|
/* Algorithm D variables will be initialized by inittapes, if needed */
|
|
|
|
state->result_tape = -1; /* flag that result tape has not been
|
|
* formed */
|
|
|
|
return state;
|
|
}
|
|
|
|
Tuplesortstate *
|
|
tuplesort_begin_heap(TupleDesc tupDesc,
|
|
int nkeys,
|
|
Oid *sortOperators, AttrNumber *attNums,
|
|
bool randomAccess)
|
|
{
|
|
Tuplesortstate *state = tuplesort_begin_common(randomAccess);
|
|
int i;
|
|
|
|
AssertArg(nkeys > 0);
|
|
|
|
state->comparetup = comparetup_heap;
|
|
state->copytup = copytup_heap;
|
|
state->writetup = writetup_heap;
|
|
state->readtup = readtup_heap;
|
|
|
|
state->tupDesc = tupDesc;
|
|
state->nKeys = nkeys;
|
|
state->scanKeys = (ScanKey) palloc(nkeys * sizeof(ScanKeyData));
|
|
MemSet(state->scanKeys, 0, nkeys * sizeof(ScanKeyData));
|
|
state->sortFnKinds = (SortFunctionKind *)
|
|
palloc(nkeys * sizeof(SortFunctionKind));
|
|
MemSet(state->sortFnKinds, 0, nkeys * sizeof(SortFunctionKind));
|
|
|
|
for (i = 0; i < nkeys; i++)
|
|
{
|
|
RegProcedure sortFunction;
|
|
|
|
AssertArg(sortOperators[i] != 0);
|
|
AssertArg(attNums[i] != 0);
|
|
|
|
/* select a function that implements the sort operator */
|
|
SelectSortFunction(sortOperators[i], &sortFunction,
|
|
&state->sortFnKinds[i]);
|
|
|
|
ScanKeyEntryInitialize(&state->scanKeys[i],
|
|
0x0,
|
|
attNums[i],
|
|
sortFunction,
|
|
(Datum) 0);
|
|
}
|
|
|
|
return state;
|
|
}
|
|
|
|
Tuplesortstate *
|
|
tuplesort_begin_index(Relation indexRel,
|
|
bool enforceUnique,
|
|
bool randomAccess)
|
|
{
|
|
Tuplesortstate *state = tuplesort_begin_common(randomAccess);
|
|
|
|
state->comparetup = comparetup_index;
|
|
state->copytup = copytup_index;
|
|
state->writetup = writetup_index;
|
|
state->readtup = readtup_index;
|
|
|
|
state->indexRel = indexRel;
|
|
/* see comments below about btree dependence of this code... */
|
|
state->indexScanKey = _bt_mkscankey_nodata(indexRel);
|
|
state->enforceUnique = enforceUnique;
|
|
|
|
return state;
|
|
}
|
|
|
|
Tuplesortstate *
|
|
tuplesort_begin_datum(Oid datumType,
|
|
Oid sortOperator,
|
|
bool randomAccess)
|
|
{
|
|
Tuplesortstate *state = tuplesort_begin_common(randomAccess);
|
|
RegProcedure sortFunction;
|
|
int16 typlen;
|
|
bool typbyval;
|
|
|
|
state->comparetup = comparetup_datum;
|
|
state->copytup = copytup_datum;
|
|
state->writetup = writetup_datum;
|
|
state->readtup = readtup_datum;
|
|
|
|
state->datumType = datumType;
|
|
state->sortOperator = sortOperator;
|
|
|
|
/* select a function that implements the sort operator */
|
|
SelectSortFunction(sortOperator, &sortFunction, &state->sortFnKind);
|
|
/* and look up the function */
|
|
fmgr_info(sortFunction, &state->sortOpFn);
|
|
|
|
/* lookup necessary attributes of the datum type */
|
|
get_typlenbyval(datumType, &typlen, &typbyval);
|
|
state->datumTypeLen = typlen;
|
|
state->datumTypeByVal = typbyval;
|
|
|
|
return state;
|
|
}
|
|
|
|
/*
|
|
* tuplesort_end
|
|
*
|
|
* Release resources and clean up.
|
|
*/
|
|
void
|
|
tuplesort_end(Tuplesortstate *state)
|
|
{
|
|
int i;
|
|
|
|
if (state->tapeset)
|
|
LogicalTapeSetClose(state->tapeset);
|
|
if (state->memtuples)
|
|
{
|
|
for (i = 0; i < state->memtupcount; i++)
|
|
pfree(state->memtuples[i]);
|
|
pfree(state->memtuples);
|
|
}
|
|
if (state->memtupindex)
|
|
pfree(state->memtupindex);
|
|
|
|
/*
|
|
* this stuff might better belong in a variant-specific shutdown
|
|
* routine
|
|
*/
|
|
if (state->scanKeys)
|
|
pfree(state->scanKeys);
|
|
if (state->sortFnKinds)
|
|
pfree(state->sortFnKinds);
|
|
|
|
pfree(state);
|
|
}
|
|
|
|
/*
|
|
* Accept one tuple while collecting input data for sort.
|
|
*
|
|
* Note that the input tuple is always copied; the caller need not save it.
|
|
*/
|
|
void
|
|
tuplesort_puttuple(Tuplesortstate *state, void *tuple)
|
|
{
|
|
/*
|
|
* Copy the given tuple into memory we control, and decrease availMem.
|
|
* Then call the code shared with the Datum case.
|
|
*/
|
|
tuple = COPYTUP(state, tuple);
|
|
|
|
puttuple_common(state, tuple);
|
|
}
|
|
|
|
/*
|
|
* Accept one Datum while collecting input data for sort.
|
|
*
|
|
* If the Datum is pass-by-ref type, the value will be copied.
|
|
*/
|
|
void
|
|
tuplesort_putdatum(Tuplesortstate *state, Datum val, bool isNull)
|
|
{
|
|
DatumTuple *tuple;
|
|
|
|
/*
|
|
* Build pseudo-tuple carrying the datum, and decrease availMem.
|
|
*/
|
|
if (isNull || state->datumTypeByVal)
|
|
{
|
|
tuple = (DatumTuple *) palloc(sizeof(DatumTuple));
|
|
tuple->val = val;
|
|
tuple->isNull = isNull;
|
|
}
|
|
else
|
|
{
|
|
int datalen = state->datumTypeLen;
|
|
int tuplelen;
|
|
char *newVal;
|
|
|
|
if (datalen == -1) /* variable length type? */
|
|
datalen = VARSIZE((struct varlena *) DatumGetPointer(val));
|
|
tuplelen = datalen + MAXALIGN(sizeof(DatumTuple));
|
|
newVal = (char *) palloc(tuplelen);
|
|
tuple = (DatumTuple *) newVal;
|
|
newVal += MAXALIGN(sizeof(DatumTuple));
|
|
memcpy(newVal, DatumGetPointer(val), datalen);
|
|
tuple->val = PointerGetDatum(newVal);
|
|
tuple->isNull = false;
|
|
}
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(tuple));
|
|
|
|
puttuple_common(state, (void *) tuple);
|
|
}
|
|
|
|
/*
|
|
* Shared code for tuple and datum cases.
|
|
*/
|
|
static void
|
|
puttuple_common(Tuplesortstate *state, void *tuple)
|
|
{
|
|
switch (state->status)
|
|
{
|
|
case TSS_INITIAL:
|
|
|
|
/*
|
|
* Save the copied tuple into the unsorted array.
|
|
*/
|
|
if (state->memtupcount >= state->memtupsize)
|
|
{
|
|
/* Grow the unsorted array as needed. */
|
|
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
state->memtupsize *= 2;
|
|
state->memtuples = (void **)
|
|
repalloc(state->memtuples,
|
|
state->memtupsize * sizeof(void *));
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
}
|
|
state->memtuples[state->memtupcount++] = tuple;
|
|
|
|
/*
|
|
* Done if we still fit in available memory.
|
|
*/
|
|
if (!LACKMEM(state))
|
|
return;
|
|
|
|
/*
|
|
* Nope; time to switch to tape-based operation.
|
|
*/
|
|
inittapes(state);
|
|
|
|
/*
|
|
* Dump tuples until we are back under the limit.
|
|
*/
|
|
dumptuples(state, false);
|
|
break;
|
|
case TSS_BUILDRUNS:
|
|
|
|
/*
|
|
* Insert the copied tuple into the heap, with run number
|
|
* currentRun if it can go into the current run, else run
|
|
* number currentRun+1. The tuple can go into the current run
|
|
* if it is >= the first not-yet-output tuple. (Actually, it
|
|
* could go into the current run if it is >= the most recently
|
|
* output tuple ... but that would require keeping around the
|
|
* tuple we last output, and it's simplest to let writetup
|
|
* free each tuple as soon as it's written.)
|
|
*
|
|
* Note there will always be at least one tuple in the heap at
|
|
* this point; see dumptuples.
|
|
*/
|
|
Assert(state->memtupcount > 0);
|
|
if (COMPARETUP(state, tuple, state->memtuples[0]) >= 0)
|
|
tuplesort_heap_insert(state, tuple, state->currentRun, true);
|
|
else
|
|
tuplesort_heap_insert(state, tuple, state->currentRun + 1, true);
|
|
|
|
/*
|
|
* If we are over the memory limit, dump tuples till we're
|
|
* under.
|
|
*/
|
|
dumptuples(state, false);
|
|
break;
|
|
default:
|
|
elog(ERROR, "tuplesort_puttuple: invalid state");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* All tuples have been provided; finish the sort.
|
|
*/
|
|
void
|
|
tuplesort_performsort(Tuplesortstate *state)
|
|
{
|
|
switch (state->status)
|
|
{
|
|
case TSS_INITIAL:
|
|
|
|
/*
|
|
* We were able to accumulate all the tuples within the
|
|
* allowed amount of memory. Just qsort 'em and we're done.
|
|
*/
|
|
if (state->memtupcount > 1)
|
|
{
|
|
qsort_tuplesortstate = state;
|
|
qsort((void *) state->memtuples, state->memtupcount,
|
|
sizeof(void *), qsort_comparetup);
|
|
}
|
|
state->current = 0;
|
|
state->eof_reached = false;
|
|
state->markpos_offset = 0;
|
|
state->markpos_eof = false;
|
|
state->status = TSS_SORTEDINMEM;
|
|
break;
|
|
case TSS_BUILDRUNS:
|
|
|
|
/*
|
|
* Finish tape-based sort. First, flush all tuples remaining
|
|
* in memory out to tape; then merge until we have a single
|
|
* remaining run (or, if !randomAccess, one run per tape).
|
|
* Note that mergeruns sets the correct state->status.
|
|
*/
|
|
dumptuples(state, true);
|
|
mergeruns(state);
|
|
state->eof_reached = false;
|
|
state->markpos_block = 0L;
|
|
state->markpos_offset = 0;
|
|
state->markpos_eof = false;
|
|
break;
|
|
default:
|
|
elog(ERROR, "tuplesort_performsort: invalid state");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Fetch the next tuple in either forward or back direction.
|
|
* Returns NULL if no more tuples. If should_free is set, the
|
|
* caller must pfree the returned tuple when done with it.
|
|
*/
|
|
void *
|
|
tuplesort_gettuple(Tuplesortstate *state, bool forward,
|
|
bool *should_free)
|
|
{
|
|
unsigned int tuplen;
|
|
void *tup;
|
|
|
|
switch (state->status)
|
|
{
|
|
case TSS_SORTEDINMEM:
|
|
Assert(forward || state->randomAccess);
|
|
*should_free = false;
|
|
if (forward)
|
|
{
|
|
if (state->current < state->memtupcount)
|
|
return state->memtuples[state->current++];
|
|
state->eof_reached = true;
|
|
return NULL;
|
|
}
|
|
else
|
|
{
|
|
if (state->current <= 0)
|
|
return NULL;
|
|
|
|
/*
|
|
* if all tuples are fetched already then we return last
|
|
* tuple, else - tuple before last returned.
|
|
*/
|
|
if (state->eof_reached)
|
|
state->eof_reached = false;
|
|
else
|
|
{
|
|
state->current--; /* last returned tuple */
|
|
if (state->current <= 0)
|
|
return NULL;
|
|
}
|
|
return state->memtuples[state->current - 1];
|
|
}
|
|
break;
|
|
|
|
case TSS_SORTEDONTAPE:
|
|
Assert(forward || state->randomAccess);
|
|
*should_free = true;
|
|
if (forward)
|
|
{
|
|
if (state->eof_reached)
|
|
return NULL;
|
|
if ((tuplen = getlen(state, state->result_tape, true)) != 0)
|
|
{
|
|
tup = READTUP(state, state->result_tape, tuplen);
|
|
return tup;
|
|
}
|
|
else
|
|
{
|
|
state->eof_reached = true;
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Backward.
|
|
*
|
|
* if all tuples are fetched already then we return last tuple,
|
|
* else - tuple before last returned.
|
|
*/
|
|
if (state->eof_reached)
|
|
{
|
|
/*
|
|
* Seek position is pointing just past the zero tuplen at
|
|
* the end of file; back up to fetch last tuple's ending
|
|
* length word. If seek fails we must have a completely
|
|
* empty file.
|
|
*/
|
|
if (!LogicalTapeBackspace(state->tapeset,
|
|
state->result_tape,
|
|
2 * sizeof(unsigned int)))
|
|
return NULL;
|
|
state->eof_reached = false;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Back up and fetch previously-returned tuple's ending
|
|
* length word. If seek fails, assume we are at start of
|
|
* file.
|
|
*/
|
|
if (!LogicalTapeBackspace(state->tapeset,
|
|
state->result_tape,
|
|
sizeof(unsigned int)))
|
|
return NULL;
|
|
tuplen = getlen(state, state->result_tape, false);
|
|
|
|
/*
|
|
* Back up to get ending length word of tuple before it.
|
|
*/
|
|
if (!LogicalTapeBackspace(state->tapeset,
|
|
state->result_tape,
|
|
tuplen + 2 * sizeof(unsigned int)))
|
|
{
|
|
/*
|
|
* If that fails, 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 (!LogicalTapeBackspace(state->tapeset,
|
|
state->result_tape,
|
|
tuplen + sizeof(unsigned int)))
|
|
elog(ERROR, "tuplesort_gettuple: bogus tuple len in backward scan");
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
tuplen = getlen(state, state->result_tape, false);
|
|
|
|
/*
|
|
* Now we have the length of the prior tuple, back up and read
|
|
* it. Note: READTUP expects we are positioned after the
|
|
* initial length word of the tuple, so back up to that point.
|
|
*/
|
|
if (!LogicalTapeBackspace(state->tapeset,
|
|
state->result_tape,
|
|
tuplen))
|
|
elog(ERROR, "tuplesort_gettuple: bogus tuple len in backward scan");
|
|
tup = READTUP(state, state->result_tape, tuplen);
|
|
return tup;
|
|
|
|
case TSS_FINALMERGE:
|
|
Assert(forward);
|
|
*should_free = true;
|
|
|
|
/*
|
|
* This code should match the inner loop of mergeonerun().
|
|
*/
|
|
if (state->memtupcount > 0)
|
|
{
|
|
int srcTape = state->memtupindex[0];
|
|
Size tuplen;
|
|
int tupIndex;
|
|
void *newtup;
|
|
|
|
tup = state->memtuples[0];
|
|
/* returned tuple is no longer counted in our memory space */
|
|
tuplen = GetMemoryChunkSpace(tup);
|
|
state->availMem += tuplen;
|
|
state->mergeavailmem[srcTape] += tuplen;
|
|
tuplesort_heap_siftup(state, false);
|
|
if ((tupIndex = state->mergenext[srcTape]) == 0)
|
|
{
|
|
/*
|
|
* out of preloaded data on this tape, try to read
|
|
* more
|
|
*/
|
|
mergepreread(state);
|
|
|
|
/*
|
|
* if still no data, we've reached end of run on this
|
|
* tape
|
|
*/
|
|
if ((tupIndex = state->mergenext[srcTape]) == 0)
|
|
return tup;
|
|
}
|
|
/* pull next preread tuple from list, insert in heap */
|
|
newtup = state->memtuples[tupIndex];
|
|
state->mergenext[srcTape] = state->memtupindex[tupIndex];
|
|
if (state->mergenext[srcTape] == 0)
|
|
state->mergelast[srcTape] = 0;
|
|
state->memtupindex[tupIndex] = state->mergefreelist;
|
|
state->mergefreelist = tupIndex;
|
|
tuplesort_heap_insert(state, newtup, srcTape, false);
|
|
return tup;
|
|
}
|
|
return NULL;
|
|
|
|
default:
|
|
elog(ERROR, "tuplesort_gettuple: invalid state");
|
|
return NULL; /* keep compiler quiet */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Fetch the next Datum in either forward or back direction.
|
|
* Returns FALSE if no more datums.
|
|
*
|
|
* If the Datum is pass-by-ref type, the returned value is freshly palloc'd
|
|
* and is now owned by the caller.
|
|
*/
|
|
bool
|
|
tuplesort_getdatum(Tuplesortstate *state, bool forward,
|
|
Datum *val, bool *isNull)
|
|
{
|
|
DatumTuple *tuple;
|
|
bool should_free;
|
|
|
|
tuple = (DatumTuple *) tuplesort_gettuple(state, forward, &should_free);
|
|
|
|
if (tuple == NULL)
|
|
return false;
|
|
|
|
if (tuple->isNull || state->datumTypeByVal)
|
|
{
|
|
*val = tuple->val;
|
|
*isNull = tuple->isNull;
|
|
}
|
|
else
|
|
{
|
|
int datalen = state->datumTypeLen;
|
|
char *newVal;
|
|
|
|
if (datalen == -1) /* variable length type? */
|
|
datalen = VARSIZE((struct varlena *) DatumGetPointer(tuple->val));
|
|
newVal = (char *) palloc(datalen);
|
|
memcpy(newVal, DatumGetPointer(tuple->val), datalen);
|
|
*val = PointerGetDatum(newVal);
|
|
*isNull = false;
|
|
}
|
|
|
|
if (should_free)
|
|
pfree(tuple);
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/*
|
|
* inittapes - initialize for tape sorting.
|
|
*
|
|
* This is called only if we have found we don't have room to sort in memory.
|
|
*/
|
|
static void
|
|
inittapes(Tuplesortstate *state)
|
|
{
|
|
int ntuples,
|
|
j;
|
|
|
|
state->tapeset = LogicalTapeSetCreate(MAXTAPES);
|
|
|
|
/*
|
|
* Allocate the memtupindex array, same size as memtuples.
|
|
*/
|
|
state->memtupindex = (int *) palloc(state->memtupsize * sizeof(int));
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtupindex));
|
|
|
|
/*
|
|
* Convert the unsorted contents of memtuples[] into a heap. Each
|
|
* tuple is marked as belonging to run number zero.
|
|
*
|
|
* NOTE: we pass false for checkIndex since there's no point in comparing
|
|
* indexes in this step, even though we do intend the indexes to be
|
|
* part of the sort key...
|
|
*/
|
|
ntuples = state->memtupcount;
|
|
state->memtupcount = 0; /* make the heap empty */
|
|
for (j = 0; j < ntuples; j++)
|
|
tuplesort_heap_insert(state, state->memtuples[j], 0, false);
|
|
Assert(state->memtupcount == ntuples);
|
|
|
|
state->currentRun = 0;
|
|
|
|
/*
|
|
* Initialize variables of Algorithm D (step D1).
|
|
*/
|
|
for (j = 0; j < MAXTAPES; j++)
|
|
{
|
|
state->tp_fib[j] = 1;
|
|
state->tp_runs[j] = 0;
|
|
state->tp_dummy[j] = 1;
|
|
state->tp_tapenum[j] = j;
|
|
}
|
|
state->tp_fib[TAPERANGE] = 0;
|
|
state->tp_dummy[TAPERANGE] = 0;
|
|
|
|
state->Level = 1;
|
|
state->destTape = 0;
|
|
|
|
state->status = TSS_BUILDRUNS;
|
|
}
|
|
|
|
/*
|
|
* selectnewtape -- select new tape for new initial run.
|
|
*
|
|
* This is called after finishing a run when we know another run
|
|
* must be started. This implements steps D3, D4 of Algorithm D.
|
|
*/
|
|
static void
|
|
selectnewtape(Tuplesortstate *state)
|
|
{
|
|
int j;
|
|
int a;
|
|
|
|
/* Step D3: advance j (destTape) */
|
|
if (state->tp_dummy[state->destTape] < state->tp_dummy[state->destTape + 1])
|
|
{
|
|
state->destTape++;
|
|
return;
|
|
}
|
|
if (state->tp_dummy[state->destTape] != 0)
|
|
{
|
|
state->destTape = 0;
|
|
return;
|
|
}
|
|
|
|
/* Step D4: increase level */
|
|
state->Level++;
|
|
a = state->tp_fib[0];
|
|
for (j = 0; j < TAPERANGE; j++)
|
|
{
|
|
state->tp_dummy[j] = a + state->tp_fib[j + 1] - state->tp_fib[j];
|
|
state->tp_fib[j] = a + state->tp_fib[j + 1];
|
|
}
|
|
state->destTape = 0;
|
|
}
|
|
|
|
/*
|
|
* mergeruns -- merge all the completed initial runs.
|
|
*
|
|
* This implements steps D5, D6 of Algorithm D. All input data has
|
|
* already been written to initial runs on tape (see dumptuples).
|
|
*/
|
|
static void
|
|
mergeruns(Tuplesortstate *state)
|
|
{
|
|
int tapenum,
|
|
svTape,
|
|
svRuns,
|
|
svDummy;
|
|
|
|
Assert(state->status == TSS_BUILDRUNS);
|
|
Assert(state->memtupcount == 0);
|
|
|
|
/*
|
|
* If we produced only one initial run (quite likely if the total data
|
|
* volume is between 1X and 2X SortMem), we can just use that tape as
|
|
* the finished output, rather than doing a useless merge.
|
|
*/
|
|
if (state->currentRun == 1)
|
|
{
|
|
state->result_tape = state->tp_tapenum[state->destTape];
|
|
/* must freeze and rewind the finished output tape */
|
|
LogicalTapeFreeze(state->tapeset, state->result_tape);
|
|
state->status = TSS_SORTEDONTAPE;
|
|
return;
|
|
}
|
|
|
|
/* End of step D2: rewind all output tapes to prepare for merging */
|
|
for (tapenum = 0; tapenum < TAPERANGE; tapenum++)
|
|
LogicalTapeRewind(state->tapeset, tapenum, false);
|
|
|
|
for (;;)
|
|
{
|
|
/* Step D5: merge runs onto tape[T] until tape[P] is empty */
|
|
while (state->tp_runs[TAPERANGE - 1] || state->tp_dummy[TAPERANGE - 1])
|
|
{
|
|
bool allDummy = true;
|
|
bool allOneRun = true;
|
|
|
|
for (tapenum = 0; tapenum < TAPERANGE; tapenum++)
|
|
{
|
|
if (state->tp_dummy[tapenum] == 0)
|
|
allDummy = false;
|
|
if (state->tp_runs[tapenum] + state->tp_dummy[tapenum] != 1)
|
|
allOneRun = false;
|
|
}
|
|
|
|
/*
|
|
* If we don't have to produce a materialized sorted tape,
|
|
* quit as soon as we're down to one real/dummy run per tape.
|
|
*/
|
|
if (!state->randomAccess && allOneRun)
|
|
{
|
|
Assert(!allDummy);
|
|
/* Initialize for the final merge pass */
|
|
beginmerge(state);
|
|
state->status = TSS_FINALMERGE;
|
|
return;
|
|
}
|
|
if (allDummy)
|
|
{
|
|
state->tp_dummy[TAPERANGE]++;
|
|
for (tapenum = 0; tapenum < TAPERANGE; tapenum++)
|
|
state->tp_dummy[tapenum]--;
|
|
}
|
|
else
|
|
mergeonerun(state);
|
|
}
|
|
/* Step D6: decrease level */
|
|
if (--state->Level == 0)
|
|
break;
|
|
/* rewind output tape T to use as new input */
|
|
LogicalTapeRewind(state->tapeset, state->tp_tapenum[TAPERANGE],
|
|
false);
|
|
/* rewind used-up input tape P, and prepare it for write pass */
|
|
LogicalTapeRewind(state->tapeset, state->tp_tapenum[TAPERANGE - 1],
|
|
true);
|
|
state->tp_runs[TAPERANGE - 1] = 0;
|
|
|
|
/*
|
|
* reassign tape units per step D6; note we no longer care about
|
|
* A[]
|
|
*/
|
|
svTape = state->tp_tapenum[TAPERANGE];
|
|
svDummy = state->tp_dummy[TAPERANGE];
|
|
svRuns = state->tp_runs[TAPERANGE];
|
|
for (tapenum = TAPERANGE; tapenum > 0; tapenum--)
|
|
{
|
|
state->tp_tapenum[tapenum] = state->tp_tapenum[tapenum - 1];
|
|
state->tp_dummy[tapenum] = state->tp_dummy[tapenum - 1];
|
|
state->tp_runs[tapenum] = state->tp_runs[tapenum - 1];
|
|
}
|
|
state->tp_tapenum[0] = svTape;
|
|
state->tp_dummy[0] = svDummy;
|
|
state->tp_runs[0] = svRuns;
|
|
}
|
|
|
|
/*
|
|
* Done. Knuth says that the result is on TAPE[1], but since we
|
|
* exited the loop without performing the last iteration of step D6,
|
|
* we have not rearranged the tape unit assignment, and therefore the
|
|
* result is on TAPE[T]. We need to do it this way so that we can
|
|
* freeze the final output tape while rewinding it. The last
|
|
* iteration of step D6 would be a waste of cycles anyway...
|
|
*/
|
|
state->result_tape = state->tp_tapenum[TAPERANGE];
|
|
LogicalTapeFreeze(state->tapeset, state->result_tape);
|
|
state->status = TSS_SORTEDONTAPE;
|
|
}
|
|
|
|
/*
|
|
* Merge one run from each input tape, except ones with dummy runs.
|
|
*
|
|
* This is the inner loop of Algorithm D step D5. We know that the
|
|
* output tape is TAPE[T].
|
|
*/
|
|
static void
|
|
mergeonerun(Tuplesortstate *state)
|
|
{
|
|
int destTape = state->tp_tapenum[TAPERANGE];
|
|
int srcTape;
|
|
int tupIndex;
|
|
void *tup;
|
|
long priorAvail,
|
|
spaceFreed;
|
|
|
|
/*
|
|
* Start the merge by loading one tuple from each active source tape
|
|
* into the heap. We can also decrease the input run/dummy run
|
|
* counts.
|
|
*/
|
|
beginmerge(state);
|
|
|
|
/*
|
|
* Execute merge by repeatedly extracting lowest tuple in heap,
|
|
* writing it out, and replacing it with next tuple from same tape (if
|
|
* there is another one).
|
|
*/
|
|
while (state->memtupcount > 0)
|
|
{
|
|
CHECK_FOR_INTERRUPTS();
|
|
/* write the tuple to destTape */
|
|
priorAvail = state->availMem;
|
|
srcTape = state->memtupindex[0];
|
|
WRITETUP(state, destTape, state->memtuples[0]);
|
|
/* writetup adjusted total free space, now fix per-tape space */
|
|
spaceFreed = state->availMem - priorAvail;
|
|
state->mergeavailmem[srcTape] += spaceFreed;
|
|
/* compact the heap */
|
|
tuplesort_heap_siftup(state, false);
|
|
if ((tupIndex = state->mergenext[srcTape]) == 0)
|
|
{
|
|
/* out of preloaded data on this tape, try to read more */
|
|
mergepreread(state);
|
|
/* if still no data, we've reached end of run on this tape */
|
|
if ((tupIndex = state->mergenext[srcTape]) == 0)
|
|
continue;
|
|
}
|
|
/* pull next preread tuple from list, insert in heap */
|
|
tup = state->memtuples[tupIndex];
|
|
state->mergenext[srcTape] = state->memtupindex[tupIndex];
|
|
if (state->mergenext[srcTape] == 0)
|
|
state->mergelast[srcTape] = 0;
|
|
state->memtupindex[tupIndex] = state->mergefreelist;
|
|
state->mergefreelist = tupIndex;
|
|
tuplesort_heap_insert(state, tup, srcTape, false);
|
|
}
|
|
|
|
/*
|
|
* When the heap empties, we're done. Write an end-of-run marker on
|
|
* the output tape, and increment its count of real runs.
|
|
*/
|
|
markrunend(state, destTape);
|
|
state->tp_runs[TAPERANGE]++;
|
|
}
|
|
|
|
/*
|
|
* beginmerge - initialize for a merge pass
|
|
*
|
|
* We decrease the counts of real and dummy runs for each tape, and mark
|
|
* which tapes contain active input runs in mergeactive[]. Then, load
|
|
* as many tuples as we can from each active input tape, and finally
|
|
* fill the merge heap with the first tuple from each active tape.
|
|
*/
|
|
static void
|
|
beginmerge(Tuplesortstate *state)
|
|
{
|
|
int activeTapes;
|
|
int tapenum;
|
|
int srcTape;
|
|
|
|
/* Heap should be empty here */
|
|
Assert(state->memtupcount == 0);
|
|
|
|
/* Clear merge-pass state variables */
|
|
memset(state->mergeactive, 0, sizeof(state->mergeactive));
|
|
memset(state->mergenext, 0, sizeof(state->mergenext));
|
|
memset(state->mergelast, 0, sizeof(state->mergelast));
|
|
memset(state->mergeavailmem, 0, sizeof(state->mergeavailmem));
|
|
state->mergefreelist = 0; /* nothing in the freelist */
|
|
state->mergefirstfree = MAXTAPES; /* first slot available for
|
|
* preread */
|
|
|
|
/* Adjust run counts and mark the active tapes */
|
|
activeTapes = 0;
|
|
for (tapenum = 0; tapenum < TAPERANGE; tapenum++)
|
|
{
|
|
if (state->tp_dummy[tapenum] > 0)
|
|
state->tp_dummy[tapenum]--;
|
|
else
|
|
{
|
|
Assert(state->tp_runs[tapenum] > 0);
|
|
state->tp_runs[tapenum]--;
|
|
srcTape = state->tp_tapenum[tapenum];
|
|
state->mergeactive[srcTape] = true;
|
|
activeTapes++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Initialize space allocation to let each active input tape have an
|
|
* equal share of preread space.
|
|
*/
|
|
Assert(activeTapes > 0);
|
|
state->spacePerTape = state->availMem / activeTapes;
|
|
for (srcTape = 0; srcTape < MAXTAPES; srcTape++)
|
|
{
|
|
if (state->mergeactive[srcTape])
|
|
state->mergeavailmem[srcTape] = state->spacePerTape;
|
|
}
|
|
|
|
/*
|
|
* Preread as many tuples as possible (and at least one) from each
|
|
* active tape
|
|
*/
|
|
mergepreread(state);
|
|
|
|
/* Load the merge heap with the first tuple from each input tape */
|
|
for (srcTape = 0; srcTape < MAXTAPES; srcTape++)
|
|
{
|
|
int tupIndex = state->mergenext[srcTape];
|
|
void *tup;
|
|
|
|
if (tupIndex)
|
|
{
|
|
tup = state->memtuples[tupIndex];
|
|
state->mergenext[srcTape] = state->memtupindex[tupIndex];
|
|
if (state->mergenext[srcTape] == 0)
|
|
state->mergelast[srcTape] = 0;
|
|
state->memtupindex[tupIndex] = state->mergefreelist;
|
|
state->mergefreelist = tupIndex;
|
|
tuplesort_heap_insert(state, tup, srcTape, false);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* mergepreread - load tuples from merge input tapes
|
|
*
|
|
* This routine exists to improve sequentiality of reads during a merge pass,
|
|
* as explained in the header comments of this file. Load tuples from each
|
|
* active source tape until the tape's run is exhausted or it has used up
|
|
* its fair share of available memory. In any case, we guarantee that there
|
|
* is at one preread tuple available from each unexhausted input tape.
|
|
*/
|
|
static void
|
|
mergepreread(Tuplesortstate *state)
|
|
{
|
|
int srcTape;
|
|
unsigned int tuplen;
|
|
void *tup;
|
|
int tupIndex;
|
|
long priorAvail,
|
|
spaceUsed;
|
|
|
|
for (srcTape = 0; srcTape < MAXTAPES; srcTape++)
|
|
{
|
|
if (!state->mergeactive[srcTape])
|
|
continue;
|
|
|
|
/*
|
|
* Skip reading from any tape that still has at least half of its
|
|
* target memory filled with tuples (threshold fraction may need
|
|
* adjustment?). This avoids reading just a few tuples when the
|
|
* incoming runs are not being consumed evenly.
|
|
*/
|
|
if (state->mergenext[srcTape] != 0 &&
|
|
state->mergeavailmem[srcTape] <= state->spacePerTape / 2)
|
|
continue;
|
|
|
|
/*
|
|
* Read tuples from this tape until it has used up its free
|
|
* memory, but ensure that we have at least one.
|
|
*/
|
|
priorAvail = state->availMem;
|
|
state->availMem = state->mergeavailmem[srcTape];
|
|
while (!LACKMEM(state) || state->mergenext[srcTape] == 0)
|
|
{
|
|
/* read next tuple, if any */
|
|
if ((tuplen = getlen(state, srcTape, true)) == 0)
|
|
{
|
|
state->mergeactive[srcTape] = false;
|
|
break;
|
|
}
|
|
tup = READTUP(state, srcTape, tuplen);
|
|
/* find or make a free slot in memtuples[] for it */
|
|
tupIndex = state->mergefreelist;
|
|
if (tupIndex)
|
|
state->mergefreelist = state->memtupindex[tupIndex];
|
|
else
|
|
{
|
|
tupIndex = state->mergefirstfree++;
|
|
/* Might need to enlarge arrays! */
|
|
if (tupIndex >= state->memtupsize)
|
|
{
|
|
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
FREEMEM(state, GetMemoryChunkSpace(state->memtupindex));
|
|
state->memtupsize *= 2;
|
|
state->memtuples = (void **)
|
|
repalloc(state->memtuples,
|
|
state->memtupsize * sizeof(void *));
|
|
state->memtupindex = (int *)
|
|
repalloc(state->memtupindex,
|
|
state->memtupsize * sizeof(int));
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtupindex));
|
|
}
|
|
}
|
|
/* store tuple, append to list for its tape */
|
|
state->memtuples[tupIndex] = tup;
|
|
state->memtupindex[tupIndex] = 0;
|
|
if (state->mergelast[srcTape])
|
|
state->memtupindex[state->mergelast[srcTape]] = tupIndex;
|
|
else
|
|
state->mergenext[srcTape] = tupIndex;
|
|
state->mergelast[srcTape] = tupIndex;
|
|
}
|
|
/* update per-tape and global availmem counts */
|
|
spaceUsed = state->mergeavailmem[srcTape] - state->availMem;
|
|
state->mergeavailmem[srcTape] = state->availMem;
|
|
state->availMem = priorAvail - spaceUsed;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* dumptuples - remove tuples from heap and write to tape
|
|
*
|
|
* This is used during initial-run building, but not during merging.
|
|
*
|
|
* When alltuples = false, dump only enough tuples to get under the
|
|
* availMem limit (and leave at least one tuple in the heap in any case,
|
|
* since puttuple assumes it always has a tuple to compare to).
|
|
*
|
|
* When alltuples = true, dump everything currently in memory.
|
|
* (This case is only used at end of input data.)
|
|
*
|
|
* If we empty the heap, close out the current run and return (this should
|
|
* only happen at end of input data). If we see that the tuple run number
|
|
* at the top of the heap has changed, start a new run.
|
|
*/
|
|
static void
|
|
dumptuples(Tuplesortstate *state, bool alltuples)
|
|
{
|
|
while (alltuples ||
|
|
(LACKMEM(state) && state->memtupcount > 1))
|
|
{
|
|
/*
|
|
* Dump the heap's frontmost entry, and sift up to remove it from
|
|
* the heap.
|
|
*/
|
|
Assert(state->memtupcount > 0);
|
|
WRITETUP(state, state->tp_tapenum[state->destTape],
|
|
state->memtuples[0]);
|
|
tuplesort_heap_siftup(state, true);
|
|
|
|
/*
|
|
* If the heap is empty *or* top run number has changed, we've
|
|
* finished the current run.
|
|
*/
|
|
if (state->memtupcount == 0 ||
|
|
state->currentRun != state->memtupindex[0])
|
|
{
|
|
markrunend(state, state->tp_tapenum[state->destTape]);
|
|
state->currentRun++;
|
|
state->tp_runs[state->destTape]++;
|
|
state->tp_dummy[state->destTape]--; /* per Alg D step D2 */
|
|
|
|
/*
|
|
* Done if heap is empty, else prepare for new run.
|
|
*/
|
|
if (state->memtupcount == 0)
|
|
break;
|
|
Assert(state->currentRun == state->memtupindex[0]);
|
|
selectnewtape(state);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* tuplesort_rescan - rewind and replay the scan
|
|
*/
|
|
void
|
|
tuplesort_rescan(Tuplesortstate *state)
|
|
{
|
|
Assert(state->randomAccess);
|
|
|
|
switch (state->status)
|
|
{
|
|
case TSS_SORTEDINMEM:
|
|
state->current = 0;
|
|
state->eof_reached = false;
|
|
state->markpos_offset = 0;
|
|
state->markpos_eof = false;
|
|
break;
|
|
case TSS_SORTEDONTAPE:
|
|
LogicalTapeRewind(state->tapeset,
|
|
state->result_tape,
|
|
false);
|
|
state->eof_reached = false;
|
|
state->markpos_block = 0L;
|
|
state->markpos_offset = 0;
|
|
state->markpos_eof = false;
|
|
break;
|
|
default:
|
|
elog(ERROR, "tuplesort_rescan: invalid state");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* tuplesort_markpos - saves current position in the merged sort file
|
|
*/
|
|
void
|
|
tuplesort_markpos(Tuplesortstate *state)
|
|
{
|
|
Assert(state->randomAccess);
|
|
|
|
switch (state->status)
|
|
{
|
|
case TSS_SORTEDINMEM:
|
|
state->markpos_offset = state->current;
|
|
state->markpos_eof = state->eof_reached;
|
|
break;
|
|
case TSS_SORTEDONTAPE:
|
|
LogicalTapeTell(state->tapeset,
|
|
state->result_tape,
|
|
&state->markpos_block,
|
|
&state->markpos_offset);
|
|
state->markpos_eof = state->eof_reached;
|
|
break;
|
|
default:
|
|
elog(ERROR, "tuplesort_markpos: invalid state");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* tuplesort_restorepos - restores current position in merged sort file to
|
|
* last saved position
|
|
*/
|
|
void
|
|
tuplesort_restorepos(Tuplesortstate *state)
|
|
{
|
|
Assert(state->randomAccess);
|
|
|
|
switch (state->status)
|
|
{
|
|
case TSS_SORTEDINMEM:
|
|
state->current = state->markpos_offset;
|
|
state->eof_reached = state->markpos_eof;
|
|
break;
|
|
case TSS_SORTEDONTAPE:
|
|
if (!LogicalTapeSeek(state->tapeset,
|
|
state->result_tape,
|
|
state->markpos_block,
|
|
state->markpos_offset))
|
|
elog(ERROR, "tuplesort_restorepos failed");
|
|
state->eof_reached = state->markpos_eof;
|
|
break;
|
|
default:
|
|
elog(ERROR, "tuplesort_restorepos: invalid state");
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* Heap manipulation routines, per Knuth's Algorithm 5.2.3H.
|
|
*
|
|
* The heap lives in state->memtuples[], with parallel data storage
|
|
* for indexes in state->memtupindex[]. If checkIndex is true, use
|
|
* the tuple index as the front of the sort key; otherwise, no.
|
|
*/
|
|
|
|
#define HEAPCOMPARE(tup1,index1,tup2,index2) \
|
|
(checkIndex && (index1 != index2) ? index1 - index2 : \
|
|
COMPARETUP(state, tup1, tup2))
|
|
|
|
/*
|
|
* Insert a new tuple into an empty or existing heap, maintaining the
|
|
* heap invariant.
|
|
*/
|
|
static void
|
|
tuplesort_heap_insert(Tuplesortstate *state, void *tuple,
|
|
int tupleindex, bool checkIndex)
|
|
{
|
|
void **memtuples;
|
|
int *memtupindex;
|
|
int j;
|
|
|
|
/*
|
|
* Make sure memtuples[] can handle another entry.
|
|
*/
|
|
if (state->memtupcount >= state->memtupsize)
|
|
{
|
|
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
FREEMEM(state, GetMemoryChunkSpace(state->memtupindex));
|
|
state->memtupsize *= 2;
|
|
state->memtuples = (void **)
|
|
repalloc(state->memtuples,
|
|
state->memtupsize * sizeof(void *));
|
|
state->memtupindex = (int *)
|
|
repalloc(state->memtupindex,
|
|
state->memtupsize * sizeof(int));
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
|
|
USEMEM(state, GetMemoryChunkSpace(state->memtupindex));
|
|
}
|
|
memtuples = state->memtuples;
|
|
memtupindex = state->memtupindex;
|
|
|
|
/*
|
|
* Sift-up the new entry, per Knuth 5.2.3 exercise 16. Note that Knuth
|
|
* is using 1-based array indexes, not 0-based.
|
|
*/
|
|
j = state->memtupcount++;
|
|
while (j > 0)
|
|
{
|
|
int i = (j - 1) >> 1;
|
|
|
|
if (HEAPCOMPARE(tuple, tupleindex,
|
|
memtuples[i], memtupindex[i]) >= 0)
|
|
break;
|
|
memtuples[j] = memtuples[i];
|
|
memtupindex[j] = memtupindex[i];
|
|
j = i;
|
|
}
|
|
memtuples[j] = tuple;
|
|
memtupindex[j] = tupleindex;
|
|
}
|
|
|
|
/*
|
|
* The tuple at state->memtuples[0] has been removed from the heap.
|
|
* Decrement memtupcount, and sift up to maintain the heap invariant.
|
|
*/
|
|
static void
|
|
tuplesort_heap_siftup(Tuplesortstate *state, bool checkIndex)
|
|
{
|
|
void **memtuples = state->memtuples;
|
|
int *memtupindex = state->memtupindex;
|
|
void *tuple;
|
|
int tupindex,
|
|
i,
|
|
n;
|
|
|
|
if (--state->memtupcount <= 0)
|
|
return;
|
|
n = state->memtupcount;
|
|
tuple = memtuples[n]; /* tuple that must be reinserted */
|
|
tupindex = memtupindex[n];
|
|
i = 0; /* i is where the "hole" is */
|
|
for (;;)
|
|
{
|
|
int j = 2 * i + 1;
|
|
|
|
if (j >= n)
|
|
break;
|
|
if (j + 1 < n &&
|
|
HEAPCOMPARE(memtuples[j], memtupindex[j],
|
|
memtuples[j + 1], memtupindex[j + 1]) > 0)
|
|
j++;
|
|
if (HEAPCOMPARE(tuple, tupindex,
|
|
memtuples[j], memtupindex[j]) <= 0)
|
|
break;
|
|
memtuples[i] = memtuples[j];
|
|
memtupindex[i] = memtupindex[j];
|
|
i = j;
|
|
}
|
|
memtuples[i] = tuple;
|
|
memtupindex[i] = tupindex;
|
|
}
|
|
|
|
|
|
/*
|
|
* Tape interface routines
|
|
*/
|
|
|
|
static unsigned int
|
|
getlen(Tuplesortstate *state, int tapenum, bool eofOK)
|
|
{
|
|
unsigned int len;
|
|
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) &len,
|
|
sizeof(len)) != sizeof(len))
|
|
elog(ERROR, "tuplesort: unexpected end of tape");
|
|
if (len == 0 && !eofOK)
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
return len;
|
|
}
|
|
|
|
static void
|
|
markrunend(Tuplesortstate *state, int tapenum)
|
|
{
|
|
unsigned int len = 0;
|
|
|
|
LogicalTapeWrite(state->tapeset, tapenum, (void *) &len, sizeof(len));
|
|
}
|
|
|
|
|
|
/*
|
|
* qsort interface
|
|
*/
|
|
|
|
static int
|
|
qsort_comparetup(const void *a, const void *b)
|
|
{
|
|
/* The passed pointers are pointers to void * ... */
|
|
|
|
return COMPARETUP(qsort_tuplesortstate, *(void **) a, *(void **) b);
|
|
}
|
|
|
|
|
|
/*
|
|
* Routines specialized for HeapTuple case
|
|
*/
|
|
|
|
static int
|
|
comparetup_heap(Tuplesortstate *state, const void *a, const void *b)
|
|
{
|
|
HeapTuple ltup = (HeapTuple) a;
|
|
HeapTuple rtup = (HeapTuple) b;
|
|
TupleDesc tupDesc = state->tupDesc;
|
|
int nkey;
|
|
|
|
for (nkey = 0; nkey < state->nKeys; nkey++)
|
|
{
|
|
ScanKey scanKey = state->scanKeys + nkey;
|
|
AttrNumber attno = scanKey->sk_attno;
|
|
Datum datum1,
|
|
datum2;
|
|
bool isnull1,
|
|
isnull2;
|
|
int32 compare;
|
|
|
|
datum1 = heap_getattr(ltup, attno, tupDesc, &isnull1);
|
|
datum2 = heap_getattr(rtup, attno, tupDesc, &isnull2);
|
|
|
|
compare = ApplySortFunction(&scanKey->sk_func,
|
|
state->sortFnKinds[nkey],
|
|
datum1, isnull1, datum2, isnull2);
|
|
if (compare != 0)
|
|
{
|
|
/* dead code? SK_COMMUTE can't actually be set here, can it? */
|
|
if (scanKey->sk_flags & SK_COMMUTE)
|
|
compare = -compare;
|
|
return compare;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void *
|
|
copytup_heap(Tuplesortstate *state, void *tup)
|
|
{
|
|
HeapTuple tuple = (HeapTuple) tup;
|
|
|
|
tuple = heap_copytuple(tuple);
|
|
USEMEM(state, GetMemoryChunkSpace(tuple));
|
|
return (void *) tuple;
|
|
}
|
|
|
|
/*
|
|
* We don't bother to write the HeapTupleData part of the tuple.
|
|
*/
|
|
|
|
static void
|
|
writetup_heap(Tuplesortstate *state, int tapenum, void *tup)
|
|
{
|
|
HeapTuple tuple = (HeapTuple) tup;
|
|
unsigned int tuplen;
|
|
|
|
tuplen = tuple->t_len + sizeof(tuplen);
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &tuplen, sizeof(tuplen));
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) tuple->t_data, tuple->t_len);
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &tuplen, sizeof(tuplen));
|
|
|
|
FREEMEM(state, GetMemoryChunkSpace(tuple));
|
|
heap_freetuple(tuple);
|
|
}
|
|
|
|
static void *
|
|
readtup_heap(Tuplesortstate *state, int tapenum, unsigned int len)
|
|
{
|
|
unsigned int tuplen = len - sizeof(unsigned int) + HEAPTUPLESIZE;
|
|
HeapTuple tuple = (HeapTuple) palloc(tuplen);
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(tuple));
|
|
/* reconstruct the HeapTupleData portion */
|
|
tuple->t_len = len - sizeof(unsigned int);
|
|
ItemPointerSetInvalid(&(tuple->t_self));
|
|
tuple->t_datamcxt = CurrentMemoryContext;
|
|
tuple->t_data = (HeapTupleHeader) (((char *) tuple) + HEAPTUPLESIZE);
|
|
/* read in the tuple proper */
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) tuple->t_data,
|
|
tuple->t_len) != tuple->t_len)
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
|
|
sizeof(tuplen)) != sizeof(tuplen))
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
return (void *) tuple;
|
|
}
|
|
|
|
|
|
/*
|
|
* Routines specialized for IndexTuple case
|
|
*
|
|
* NOTE: actually, these are specialized for the btree case; it's not
|
|
* clear whether you could use them for a non-btree index. Possibly
|
|
* you'd need to make another set of routines if you needed to sort
|
|
* according to another kind of index.
|
|
*/
|
|
|
|
static int
|
|
comparetup_index(Tuplesortstate *state, const void *a, const void *b)
|
|
{
|
|
/*
|
|
* This is almost the same as _bt_tuplecompare(), but we need to keep
|
|
* track of whether any null fields are present.
|
|
*/
|
|
IndexTuple tuple1 = (IndexTuple) a;
|
|
IndexTuple tuple2 = (IndexTuple) b;
|
|
Relation rel = state->indexRel;
|
|
int keysz = RelationGetNumberOfAttributes(rel);
|
|
ScanKey scankey = state->indexScanKey;
|
|
TupleDesc tupDes;
|
|
int i;
|
|
bool equal_hasnull = false;
|
|
|
|
tupDes = RelationGetDescr(rel);
|
|
|
|
for (i = 1; i <= keysz; i++)
|
|
{
|
|
ScanKey entry = &scankey[i - 1];
|
|
Datum datum1,
|
|
datum2;
|
|
bool isnull1,
|
|
isnull2;
|
|
int32 compare;
|
|
|
|
datum1 = index_getattr(tuple1, i, tupDes, &isnull1);
|
|
datum2 = index_getattr(tuple2, i, tupDes, &isnull2);
|
|
|
|
/* see comments about NULLs handling in btbuild */
|
|
|
|
/* the comparison function is always of CMP type */
|
|
compare = ApplySortFunction(&entry->sk_func, SORTFUNC_CMP,
|
|
datum1, isnull1, datum2, isnull2);
|
|
|
|
if (compare != 0)
|
|
return (int) compare; /* done when we find unequal
|
|
* attributes */
|
|
|
|
/* they are equal, so we only need to examine one null flag */
|
|
if (isnull1)
|
|
equal_hasnull = true;
|
|
}
|
|
|
|
/*
|
|
* If btree has asked us to enforce uniqueness, complain if two equal
|
|
* tuples are detected (unless there was at least one NULL field).
|
|
*
|
|
* It is sufficient to make the test here, because if two tuples are
|
|
* equal they *must* get compared at some stage of the sort ---
|
|
* otherwise the sort algorithm wouldn't have checked whether one must
|
|
* appear before the other.
|
|
*
|
|
* Some rather brain-dead implementations of qsort will sometimes
|
|
* call the comparison routine to compare a value to itself. (At this
|
|
* writing only QNX 4 is known to do such silly things.) Don't raise
|
|
* a bogus error in that case.
|
|
*/
|
|
if (state->enforceUnique && !equal_hasnull && tuple1 != tuple2)
|
|
elog(ERROR, "Cannot create unique index. Table contains non-unique values");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void *
|
|
copytup_index(Tuplesortstate *state, void *tup)
|
|
{
|
|
IndexTuple tuple = (IndexTuple) tup;
|
|
unsigned int tuplen = IndexTupleSize(tuple);
|
|
IndexTuple newtuple;
|
|
|
|
newtuple = (IndexTuple) palloc(tuplen);
|
|
USEMEM(state, GetMemoryChunkSpace(newtuple));
|
|
|
|
memcpy(newtuple, tuple, tuplen);
|
|
|
|
return (void *) newtuple;
|
|
}
|
|
|
|
static void
|
|
writetup_index(Tuplesortstate *state, int tapenum, void *tup)
|
|
{
|
|
IndexTuple tuple = (IndexTuple) tup;
|
|
unsigned int tuplen;
|
|
|
|
tuplen = IndexTupleSize(tuple) + sizeof(tuplen);
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &tuplen, sizeof(tuplen));
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) tuple, IndexTupleSize(tuple));
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &tuplen, sizeof(tuplen));
|
|
|
|
FREEMEM(state, GetMemoryChunkSpace(tuple));
|
|
pfree(tuple);
|
|
}
|
|
|
|
static void *
|
|
readtup_index(Tuplesortstate *state, int tapenum, unsigned int len)
|
|
{
|
|
unsigned int tuplen = len - sizeof(unsigned int);
|
|
IndexTuple tuple = (IndexTuple) palloc(tuplen);
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(tuple));
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) tuple,
|
|
tuplen) != tuplen)
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
|
|
sizeof(tuplen)) != sizeof(tuplen))
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
return (void *) tuple;
|
|
}
|
|
|
|
|
|
/*
|
|
* Routines specialized for DatumTuple case
|
|
*/
|
|
|
|
static int
|
|
comparetup_datum(Tuplesortstate *state, const void *a, const void *b)
|
|
{
|
|
DatumTuple *ltup = (DatumTuple *) a;
|
|
DatumTuple *rtup = (DatumTuple *) b;
|
|
|
|
return ApplySortFunction(&state->sortOpFn, state->sortFnKind,
|
|
ltup->val, ltup->isNull,
|
|
rtup->val, rtup->isNull);
|
|
}
|
|
|
|
static void *
|
|
copytup_datum(Tuplesortstate *state, void *tup)
|
|
{
|
|
/* Not currently needed */
|
|
elog(ERROR, "copytup_datum() should not be called");
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
writetup_datum(Tuplesortstate *state, int tapenum, void *tup)
|
|
{
|
|
DatumTuple *tuple = (DatumTuple *) tup;
|
|
unsigned int tuplen;
|
|
unsigned int writtenlen;
|
|
|
|
if (tuple->isNull || state->datumTypeByVal)
|
|
tuplen = sizeof(DatumTuple);
|
|
else
|
|
{
|
|
int datalen = state->datumTypeLen;
|
|
|
|
if (datalen == -1) /* variable length type? */
|
|
datalen = VARSIZE((struct varlena *) DatumGetPointer(tuple->val));
|
|
tuplen = datalen + MAXALIGN(sizeof(DatumTuple));
|
|
}
|
|
|
|
writtenlen = tuplen + sizeof(unsigned int);
|
|
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &writtenlen, sizeof(writtenlen));
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) tuple, tuplen);
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
LogicalTapeWrite(state->tapeset, tapenum,
|
|
(void *) &writtenlen, sizeof(writtenlen));
|
|
|
|
FREEMEM(state, GetMemoryChunkSpace(tuple));
|
|
pfree(tuple);
|
|
}
|
|
|
|
static void *
|
|
readtup_datum(Tuplesortstate *state, int tapenum, unsigned int len)
|
|
{
|
|
unsigned int tuplen = len - sizeof(unsigned int);
|
|
DatumTuple *tuple = (DatumTuple *) palloc(tuplen);
|
|
|
|
USEMEM(state, GetMemoryChunkSpace(tuple));
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) tuple,
|
|
tuplen) != tuplen)
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
if (state->randomAccess) /* need trailing length word? */
|
|
if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
|
|
sizeof(tuplen)) != sizeof(tuplen))
|
|
elog(ERROR, "tuplesort: unexpected end of data");
|
|
|
|
if (!tuple->isNull && !state->datumTypeByVal)
|
|
tuple->val = PointerGetDatum(((char *) tuple) +
|
|
MAXALIGN(sizeof(DatumTuple)));
|
|
return (void *) tuple;
|
|
}
|
|
|
|
|
|
/*
|
|
* This routine selects an appropriate sorting function to implement
|
|
* a sort operator as efficiently as possible. The straightforward
|
|
* method is to use the operator's implementation proc --- ie, "<"
|
|
* comparison. However, that way often requires two calls of the function
|
|
* per comparison. If we can find a btree three-way comparator function
|
|
* associated with the operator, we can use it to do the comparisons
|
|
* more efficiently. We also support the possibility that the operator
|
|
* is ">" (descending sort), in which case we have to reverse the output
|
|
* of the btree comparator.
|
|
*
|
|
* Possibly this should live somewhere else (backend/catalog/, maybe?).
|
|
*/
|
|
void
|
|
SelectSortFunction(Oid sortOperator,
|
|
RegProcedure *sortFunction,
|
|
SortFunctionKind *kind)
|
|
{
|
|
Relation relation;
|
|
HeapScanDesc scan;
|
|
ScanKeyData skey[1];
|
|
HeapTuple tuple;
|
|
Form_pg_operator optup;
|
|
Oid opclass = InvalidOid;
|
|
|
|
/*
|
|
* Scan pg_amop to see if the target operator is registered as the "<"
|
|
* or ">" operator of any btree opclass. It's possible that it might
|
|
* be registered both ways (eg, if someone were to build a "reverse
|
|
* sort" opclass for some reason); prefer the "<" case if so. If the
|
|
* operator is registered the same way in multiple opclasses, assume
|
|
* we can use the associated comparator function from any one.
|
|
*/
|
|
ScanKeyEntryInitialize(&skey[0], 0x0,
|
|
Anum_pg_amop_amopopr,
|
|
F_OIDEQ,
|
|
ObjectIdGetDatum(sortOperator));
|
|
|
|
relation = heap_openr(AccessMethodOperatorRelationName, AccessShareLock);
|
|
scan = heap_beginscan(relation, SnapshotNow, 1, skey);
|
|
|
|
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
|
|
{
|
|
Form_pg_amop aform = (Form_pg_amop) GETSTRUCT(tuple);
|
|
|
|
if (!opclass_is_btree(aform->amopclaid))
|
|
continue;
|
|
if (aform->amopstrategy == BTLessStrategyNumber)
|
|
{
|
|
opclass = aform->amopclaid;
|
|
*kind = SORTFUNC_CMP;
|
|
break; /* done looking */
|
|
}
|
|
else if (aform->amopstrategy == BTGreaterStrategyNumber)
|
|
{
|
|
opclass = aform->amopclaid;
|
|
*kind = SORTFUNC_REVCMP;
|
|
/* keep scanning in hopes of finding a BTLess entry */
|
|
}
|
|
}
|
|
|
|
heap_endscan(scan);
|
|
heap_close(relation, AccessShareLock);
|
|
|
|
if (OidIsValid(opclass))
|
|
{
|
|
/* Found a suitable opclass, get its comparator support function */
|
|
tuple = SearchSysCache(AMPROCNUM,
|
|
ObjectIdGetDatum(opclass),
|
|
Int16GetDatum(BTORDER_PROC),
|
|
0, 0);
|
|
if (HeapTupleIsValid(tuple))
|
|
{
|
|
Form_pg_amproc aform = (Form_pg_amproc) GETSTRUCT(tuple);
|
|
|
|
*sortFunction = aform->amproc;
|
|
ReleaseSysCache(tuple);
|
|
Assert(RegProcedureIsValid(*sortFunction));
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Can't find a comparator, so use the operator as-is. Decide whether
|
|
* it is forward or reverse sort by looking at its name (grotty, but
|
|
* this only matters for deciding which end NULLs should get sorted
|
|
* to).
|
|
*/
|
|
tuple = SearchSysCache(OPEROID,
|
|
ObjectIdGetDatum(sortOperator),
|
|
0, 0, 0);
|
|
if (!HeapTupleIsValid(tuple))
|
|
elog(ERROR, "SelectSortFunction: cache lookup failed for operator %u",
|
|
sortOperator);
|
|
optup = (Form_pg_operator) GETSTRUCT(tuple);
|
|
if (strcmp(NameStr(optup->oprname), ">") == 0)
|
|
*kind = SORTFUNC_REVLT;
|
|
else
|
|
*kind = SORTFUNC_LT;
|
|
*sortFunction = optup->oprcode;
|
|
ReleaseSysCache(tuple);
|
|
|
|
Assert(RegProcedureIsValid(*sortFunction));
|
|
}
|
|
|
|
/*
|
|
* Apply a sort function (by now converted to fmgr lookup form)
|
|
* and return a 3-way comparison result. This takes care of handling
|
|
* NULLs and sort ordering direction properly.
|
|
*/
|
|
int32
|
|
ApplySortFunction(FmgrInfo *sortFunction, SortFunctionKind kind,
|
|
Datum datum1, bool isNull1,
|
|
Datum datum2, bool isNull2)
|
|
{
|
|
switch (kind)
|
|
{
|
|
case SORTFUNC_LT:
|
|
if (isNull1)
|
|
{
|
|
if (isNull2)
|
|
return 0;
|
|
return 1; /* NULL sorts after non-NULL */
|
|
}
|
|
if (isNull2)
|
|
return -1;
|
|
if (DatumGetBool(FunctionCall2(sortFunction, datum1, datum2)))
|
|
return -1; /* a < b */
|
|
if (DatumGetBool(FunctionCall2(sortFunction, datum2, datum1)))
|
|
return 1; /* a > b */
|
|
return 0;
|
|
|
|
case SORTFUNC_REVLT:
|
|
/* We reverse the ordering of NULLs, but not the operator */
|
|
if (isNull1)
|
|
{
|
|
if (isNull2)
|
|
return 0;
|
|
return -1; /* NULL sorts before non-NULL */
|
|
}
|
|
if (isNull2)
|
|
return 1;
|
|
if (DatumGetBool(FunctionCall2(sortFunction, datum1, datum2)))
|
|
return -1; /* a < b */
|
|
if (DatumGetBool(FunctionCall2(sortFunction, datum2, datum1)))
|
|
return 1; /* a > b */
|
|
return 0;
|
|
|
|
case SORTFUNC_CMP:
|
|
if (isNull1)
|
|
{
|
|
if (isNull2)
|
|
return 0;
|
|
return 1; /* NULL sorts after non-NULL */
|
|
}
|
|
if (isNull2)
|
|
return -1;
|
|
return DatumGetInt32(FunctionCall2(sortFunction,
|
|
datum1, datum2));
|
|
|
|
case SORTFUNC_REVCMP:
|
|
if (isNull1)
|
|
{
|
|
if (isNull2)
|
|
return 0;
|
|
return -1; /* NULL sorts before non-NULL */
|
|
}
|
|
if (isNull2)
|
|
return 1;
|
|
return -DatumGetInt32(FunctionCall2(sortFunction,
|
|
datum1, datum2));
|
|
|
|
default:
|
|
elog(ERROR, "Invalid SortFunctionKind %d", (int) kind);
|
|
return 0; /* can't get here, but keep compiler quiet */
|
|
}
|
|
}
|