89 lines
3.2 KiB
C
89 lines
3.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuplestore.h
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* Generalized routines for temporary tuple storage.
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*
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* This module handles temporary storage of tuples for purposes such
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* as Materialize nodes, hashjoin batch files, etc. It is essentially
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* a dumbed-down version of tuplesort.c; it does no sorting of tuples
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* but can only store and regurgitate a sequence of tuples. However,
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* because no sort is required, it is allowed to start reading the sequence
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* before it has all been written. This is particularly useful for cursors,
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* because it allows random access within the already-scanned portion of
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* a query without having to process the underlying scan to completion.
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* Also, it is possible to support multiple independent read pointers.
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*
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* A temporary file is used to handle the data if it exceeds the
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* space limit specified by the caller.
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*
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* Beginning in Postgres 8.2, what is stored is just MinimalTuples;
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* callers cannot expect valid system columns in regurgitated tuples.
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* Also, we have changed the API to return tuples in TupleTableSlots,
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* so that there is a check to prevent attempted access to system columns.
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*
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* Portions Copyright (c) 1996-2024, 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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* src/include/utils/tuplestore.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPLESTORE_H
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#define TUPLESTORE_H
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#include "executor/tuptable.h"
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/* Tuplestorestate is an opaque type whose details are not known outside
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* tuplestore.c.
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*/
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typedef struct Tuplestorestate Tuplestorestate;
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/*
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* Currently we only need to store MinimalTuples, but it would be easy
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* to support the same behavior for IndexTuples and/or bare Datums.
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*/
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extern Tuplestorestate *tuplestore_begin_heap(bool randomAccess,
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bool interXact,
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int maxKBytes);
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extern void tuplestore_set_eflags(Tuplestorestate *state, int eflags);
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extern void tuplestore_puttupleslot(Tuplestorestate *state,
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TupleTableSlot *slot);
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extern void tuplestore_puttuple(Tuplestorestate *state, HeapTuple tuple);
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extern void tuplestore_putvalues(Tuplestorestate *state, TupleDesc tdesc,
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const Datum *values, const bool *isnull);
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extern int tuplestore_alloc_read_pointer(Tuplestorestate *state, int eflags);
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extern void tuplestore_select_read_pointer(Tuplestorestate *state, int ptr);
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extern void tuplestore_copy_read_pointer(Tuplestorestate *state,
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int srcptr, int destptr);
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extern void tuplestore_trim(Tuplestorestate *state);
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extern bool tuplestore_in_memory(Tuplestorestate *state);
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extern bool tuplestore_gettupleslot(Tuplestorestate *state, bool forward,
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bool copy, TupleTableSlot *slot);
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extern bool tuplestore_advance(Tuplestorestate *state, bool forward);
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extern bool tuplestore_skiptuples(Tuplestorestate *state,
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int64 ntuples, bool forward);
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extern int64 tuplestore_tuple_count(Tuplestorestate *state);
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extern bool tuplestore_ateof(Tuplestorestate *state);
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extern void tuplestore_rescan(Tuplestorestate *state);
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extern void tuplestore_clear(Tuplestorestate *state);
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extern void tuplestore_end(Tuplestorestate *state);
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#endif /* TUPLESTORE_H */
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