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A QueryEnvironment concept is added, which allows new types of objects to be passed into queries from parsing on through execution. At this point, the only thing implemented is a collection of EphemeralNamedRelation objects -- relations which can be referenced by name in queries, but do not exist in the catalogs. The only type of ENR implemented is NamedTuplestore, but provision is made to add more types fairly easily. An ENR can carry its own TupleDesc or reference a relation in the catalogs by relid. Although these features can be used without SPI, convenience functions are added to SPI so that ENRs can easily be used by code run through SPI. The initial use of all this is going to be transition tables in AFTER triggers, but that will be added to each PL as a separate commit. An incidental effect of this patch is to produce a more informative error message if an attempt is made to modify the contents of a CTE from a referencing DML statement. No tests previously covered that possibility, so one is added. Kevin Grittner and Thomas Munro Reviewed by Heikki Linnakangas, David Fetter, and Thomas Munro with valuable comments and suggestions from many others
92 lines
3.3 KiB
C
92 lines
3.3 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) 1996-2017, 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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Datum *values, bool *isnull);
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/* tuplestore_donestoring() used to be required, but is no longer used */
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#define tuplestore_donestoring(state) ((void) 0)
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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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