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Split tuptoaster.c into three separate files.
detoast.c/h contain functions required to detoast a datum, partially or completely, plus a few other utility functions for examining the size of toasted datums. toast_internals.c/h contain functions that are used internally to the TOAST subsystem but which (mostly) do not need to be accessed from outside. heaptoast.c/h contains code that is intrinsically specific to the heap AM, either because it operates on HeapTuples or is based on the layout of a heap page. detoast.c and toast_internals.c are placed in src/backend/access/common rather than src/backend/access/heap. At present, both files still have dependencies on the heap, but that will be improved in a future commit. Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro, Andres Freund, and Álvaro Herrera. Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
This commit is contained in:
Robert Haas
917
src/backend/access/heap/heaptoast.c
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917
src/backend/access/heap/heaptoast.c
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@@ -0,0 +1,917 @@
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/*-------------------------------------------------------------------------
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*
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* heaptoast.c
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* Heap-specific definitions for external and compressed storage
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* of variable size attributes.
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*
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* Copyright (c) 2000-2019, PostgreSQL Global Development Group
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*
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*
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* IDENTIFICATION
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* src/backend/access/heap/heaptoast.c
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*
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*
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* INTERFACE ROUTINES
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* toast_insert_or_update -
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* Try to make a given tuple fit into one page by compressing
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* or moving off attributes
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*
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* toast_delete -
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* Reclaim toast storage when a tuple is deleted
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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/detoast.h"
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#include "access/heapam.h"
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#include "access/heaptoast.h"
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#include "access/toast_internals.h"
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/* ----------
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* toast_delete -
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*
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* Cascaded delete toast-entries on DELETE
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* ----------
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*/
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void
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toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
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{
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TupleDesc tupleDesc;
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int numAttrs;
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int i;
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Datum toast_values[MaxHeapAttributeNumber];
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bool toast_isnull[MaxHeapAttributeNumber];
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/*
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* We should only ever be called for tuples of plain relations or
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* materialized views --- recursing on a toast rel is bad news.
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*/
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Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
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rel->rd_rel->relkind == RELKIND_MATVIEW);
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/*
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* Get the tuple descriptor and break down the tuple into fields.
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*
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* NOTE: it's debatable whether to use heap_deform_tuple() here or just
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* heap_getattr() only the varlena columns. The latter could win if there
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* are few varlena columns and many non-varlena ones. However,
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* heap_deform_tuple costs only O(N) while the heap_getattr way would cost
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* O(N^2) if there are many varlena columns, so it seems better to err on
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* the side of linear cost. (We won't even be here unless there's at
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* least one varlena column, by the way.)
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*/
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tupleDesc = rel->rd_att;
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numAttrs = tupleDesc->natts;
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Assert(numAttrs <= MaxHeapAttributeNumber);
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heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
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/*
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* Check for external stored attributes and delete them from the secondary
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* relation.
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*/
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for (i = 0; i < numAttrs; i++)
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{
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if (TupleDescAttr(tupleDesc, i)->attlen == -1)
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{
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Datum value = toast_values[i];
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if (toast_isnull[i])
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continue;
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else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
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toast_delete_datum(rel, value, is_speculative);
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}
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}
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}
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/* ----------
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* toast_insert_or_update -
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*
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* Delete no-longer-used toast-entries and create new ones to
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* make the new tuple fit on INSERT or UPDATE
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*
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* Inputs:
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* newtup: the candidate new tuple to be inserted
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* oldtup: the old row version for UPDATE, or NULL for INSERT
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* options: options to be passed to heap_insert() for toast rows
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* Result:
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* either newtup if no toasting is needed, or a palloc'd modified tuple
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* that is what should actually get stored
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*
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* NOTE: neither newtup nor oldtup will be modified. This is a change
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* from the pre-8.1 API of this routine.
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* ----------
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*/
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HeapTuple
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toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
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int options)
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{
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HeapTuple result_tuple;
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TupleDesc tupleDesc;
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int numAttrs;
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int i;
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bool need_change = false;
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bool need_free = false;
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bool need_delold = false;
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bool has_nulls = false;
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Size maxDataLen;
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Size hoff;
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char toast_action[MaxHeapAttributeNumber];
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bool toast_isnull[MaxHeapAttributeNumber];
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bool toast_oldisnull[MaxHeapAttributeNumber];
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Datum toast_values[MaxHeapAttributeNumber];
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Datum toast_oldvalues[MaxHeapAttributeNumber];
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struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
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int32 toast_sizes[MaxHeapAttributeNumber];
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bool toast_free[MaxHeapAttributeNumber];
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bool toast_delold[MaxHeapAttributeNumber];
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/*
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* Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
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* deletions just normally insert/delete the toast values. It seems
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* easiest to deal with that here, instead on, potentially, multiple
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* callers.
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*/
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options &= ~HEAP_INSERT_SPECULATIVE;
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/*
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* We should only ever be called for tuples of plain relations or
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* materialized views --- recursing on a toast rel is bad news.
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*/
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Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
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rel->rd_rel->relkind == RELKIND_MATVIEW);
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/*
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* Get the tuple descriptor and break down the tuple(s) into fields.
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*/
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tupleDesc = rel->rd_att;
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numAttrs = tupleDesc->natts;
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Assert(numAttrs <= MaxHeapAttributeNumber);
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heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
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if (oldtup != NULL)
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heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
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/* ----------
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* Then collect information about the values given
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*
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* NOTE: toast_action[i] can have these values:
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* ' ' default handling
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* 'p' already processed --- don't touch it
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* 'x' incompressible, but OK to move off
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*
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* NOTE: toast_sizes[i] is only made valid for varlena attributes with
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* toast_action[i] different from 'p'.
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* ----------
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*/
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memset(toast_action, ' ', numAttrs * sizeof(char));
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memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
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memset(toast_free, 0, numAttrs * sizeof(bool));
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memset(toast_delold, 0, numAttrs * sizeof(bool));
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for (i = 0; i < numAttrs; i++)
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{
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Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
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struct varlena *old_value;
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struct varlena *new_value;
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if (oldtup != NULL)
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{
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/*
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* For UPDATE get the old and new values of this attribute
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*/
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old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
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new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
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/*
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* If the old value is stored on disk, check if it has changed so
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* we have to delete it later.
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*/
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if (att->attlen == -1 && !toast_oldisnull[i] &&
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VARATT_IS_EXTERNAL_ONDISK(old_value))
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{
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if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
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memcmp((char *) old_value, (char *) new_value,
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VARSIZE_EXTERNAL(old_value)) != 0)
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{
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/*
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* The old external stored value isn't needed any more
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* after the update
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*/
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toast_delold[i] = true;
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need_delold = true;
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}
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else
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{
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/*
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* This attribute isn't changed by this update so we reuse
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* the original reference to the old value in the new
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* tuple.
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*/
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toast_action[i] = 'p';
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continue;
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}
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}
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}
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else
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{
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/*
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* For INSERT simply get the new value
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*/
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new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
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}
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/*
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* Handle NULL attributes
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*/
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if (toast_isnull[i])
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{
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toast_action[i] = 'p';
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has_nulls = true;
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continue;
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}
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/*
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* Now look at varlena attributes
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*/
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if (att->attlen == -1)
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{
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/*
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* If the table's attribute says PLAIN always, force it so.
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*/
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if (att->attstorage == 'p')
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toast_action[i] = 'p';
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/*
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* We took care of UPDATE above, so any external value we find
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* still in the tuple must be someone else's that we cannot reuse
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* (this includes the case of an out-of-line in-memory datum).
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* Fetch it back (without decompression, unless we are forcing
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* PLAIN storage). If necessary, we'll push it out as a new
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* external value below.
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*/
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if (VARATT_IS_EXTERNAL(new_value))
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{
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toast_oldexternal[i] = new_value;
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if (att->attstorage == 'p')
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new_value = heap_tuple_untoast_attr(new_value);
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else
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new_value = heap_tuple_fetch_attr(new_value);
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toast_values[i] = PointerGetDatum(new_value);
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toast_free[i] = true;
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need_change = true;
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need_free = true;
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}
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/*
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* Remember the size of this attribute
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*/
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toast_sizes[i] = VARSIZE_ANY(new_value);
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}
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else
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{
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/*
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* Not a varlena attribute, plain storage always
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*/
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toast_action[i] = 'p';
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}
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}
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/* ----------
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* Compress and/or save external until data fits into target length
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*
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* 1: Inline compress attributes with attstorage 'x', and store very
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* large attributes with attstorage 'x' or 'e' external immediately
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* 2: Store attributes with attstorage 'x' or 'e' external
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* 3: Inline compress attributes with attstorage 'm'
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* 4: Store attributes with attstorage 'm' external
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* ----------
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*/
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/* compute header overhead --- this should match heap_form_tuple() */
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hoff = SizeofHeapTupleHeader;
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if (has_nulls)
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hoff += BITMAPLEN(numAttrs);
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hoff = MAXALIGN(hoff);
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/* now convert to a limit on the tuple data size */
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maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
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/*
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* Look for attributes with attstorage 'x' to compress. Also find large
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* attributes with attstorage 'x' or 'e', and store them external.
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*/
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while (heap_compute_data_size(tupleDesc,
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toast_values, toast_isnull) > maxDataLen)
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{
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int biggest_attno = -1;
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int32 biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
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Datum old_value;
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Datum new_value;
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/*
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* Search for the biggest yet unprocessed internal attribute
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*/
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for (i = 0; i < numAttrs; i++)
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{
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Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
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if (toast_action[i] != ' ')
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continue;
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if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
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continue; /* can't happen, toast_action would be 'p' */
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if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
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continue;
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if (att->attstorage != 'x' && att->attstorage != 'e')
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continue;
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if (toast_sizes[i] > biggest_size)
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{
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biggest_attno = i;
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biggest_size = toast_sizes[i];
|
||||
}
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}
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if (biggest_attno < 0)
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break;
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/*
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* Attempt to compress it inline, if it has attstorage 'x'
|
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*/
|
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i = biggest_attno;
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if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
|
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{
|
||||
old_value = toast_values[i];
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new_value = toast_compress_datum(old_value);
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if (DatumGetPointer(new_value) != NULL)
|
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{
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/* successful compression */
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if (toast_free[i])
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pfree(DatumGetPointer(old_value));
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toast_values[i] = new_value;
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toast_free[i] = true;
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toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
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need_change = true;
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need_free = true;
|
||||
}
|
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else
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{
|
||||
/* incompressible, ignore on subsequent compression passes */
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||||
toast_action[i] = 'x';
|
||||
}
|
||||
}
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||||
else
|
||||
{
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/* has attstorage 'e', ignore on subsequent compression passes */
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||||
toast_action[i] = 'x';
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}
|
||||
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||||
/*
|
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* If this value is by itself more than maxDataLen (after compression
|
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* if any), push it out to the toast table immediately, if possible.
|
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* This avoids uselessly compressing other fields in the common case
|
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* where we have one long field and several short ones.
|
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*
|
||||
* XXX maybe the threshold should be less than maxDataLen?
|
||||
*/
|
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if (toast_sizes[i] > maxDataLen &&
|
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rel->rd_rel->reltoastrelid != InvalidOid)
|
||||
{
|
||||
old_value = toast_values[i];
|
||||
toast_action[i] = 'p';
|
||||
toast_values[i] = toast_save_datum(rel, toast_values[i],
|
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toast_oldexternal[i], options);
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(old_value));
|
||||
toast_free[i] = true;
|
||||
need_change = true;
|
||||
need_free = true;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Second we look for attributes of attstorage 'x' or 'e' that are still
|
||||
* inline. But skip this if there's no toast table to push them to.
|
||||
*/
|
||||
while (heap_compute_data_size(tupleDesc,
|
||||
toast_values, toast_isnull) > maxDataLen &&
|
||||
rel->rd_rel->reltoastrelid != InvalidOid)
|
||||
{
|
||||
int biggest_attno = -1;
|
||||
int32 biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
|
||||
Datum old_value;
|
||||
|
||||
/*------
|
||||
* Search for the biggest yet inlined attribute with
|
||||
* attstorage equals 'x' or 'e'
|
||||
*------
|
||||
*/
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
|
||||
|
||||
if (toast_action[i] == 'p')
|
||||
continue;
|
||||
if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
|
||||
continue; /* can't happen, toast_action would be 'p' */
|
||||
if (att->attstorage != 'x' && att->attstorage != 'e')
|
||||
continue;
|
||||
if (toast_sizes[i] > biggest_size)
|
||||
{
|
||||
biggest_attno = i;
|
||||
biggest_size = toast_sizes[i];
|
||||
}
|
||||
}
|
||||
|
||||
if (biggest_attno < 0)
|
||||
break;
|
||||
|
||||
/*
|
||||
* Store this external
|
||||
*/
|
||||
i = biggest_attno;
|
||||
old_value = toast_values[i];
|
||||
toast_action[i] = 'p';
|
||||
toast_values[i] = toast_save_datum(rel, toast_values[i],
|
||||
toast_oldexternal[i], options);
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(old_value));
|
||||
toast_free[i] = true;
|
||||
|
||||
need_change = true;
|
||||
need_free = true;
|
||||
}
|
||||
|
||||
/*
|
||||
* Round 3 - this time we take attributes with storage 'm' into
|
||||
* compression
|
||||
*/
|
||||
while (heap_compute_data_size(tupleDesc,
|
||||
toast_values, toast_isnull) > maxDataLen)
|
||||
{
|
||||
int biggest_attno = -1;
|
||||
int32 biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
|
||||
Datum old_value;
|
||||
Datum new_value;
|
||||
|
||||
/*
|
||||
* Search for the biggest yet uncompressed internal attribute
|
||||
*/
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
if (toast_action[i] != ' ')
|
||||
continue;
|
||||
if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
|
||||
continue; /* can't happen, toast_action would be 'p' */
|
||||
if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
|
||||
continue;
|
||||
if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
|
||||
continue;
|
||||
if (toast_sizes[i] > biggest_size)
|
||||
{
|
||||
biggest_attno = i;
|
||||
biggest_size = toast_sizes[i];
|
||||
}
|
||||
}
|
||||
|
||||
if (biggest_attno < 0)
|
||||
break;
|
||||
|
||||
/*
|
||||
* Attempt to compress it inline
|
||||
*/
|
||||
i = biggest_attno;
|
||||
old_value = toast_values[i];
|
||||
new_value = toast_compress_datum(old_value);
|
||||
|
||||
if (DatumGetPointer(new_value) != NULL)
|
||||
{
|
||||
/* successful compression */
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(old_value));
|
||||
toast_values[i] = new_value;
|
||||
toast_free[i] = true;
|
||||
toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
|
||||
need_change = true;
|
||||
need_free = true;
|
||||
}
|
||||
else
|
||||
{
|
||||
/* incompressible, ignore on subsequent compression passes */
|
||||
toast_action[i] = 'x';
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Finally we store attributes of type 'm' externally. At this point we
|
||||
* increase the target tuple size, so that 'm' attributes aren't stored
|
||||
* externally unless really necessary.
|
||||
*/
|
||||
maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
|
||||
|
||||
while (heap_compute_data_size(tupleDesc,
|
||||
toast_values, toast_isnull) > maxDataLen &&
|
||||
rel->rd_rel->reltoastrelid != InvalidOid)
|
||||
{
|
||||
int biggest_attno = -1;
|
||||
int32 biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
|
||||
Datum old_value;
|
||||
|
||||
/*--------
|
||||
* Search for the biggest yet inlined attribute with
|
||||
* attstorage = 'm'
|
||||
*--------
|
||||
*/
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
if (toast_action[i] == 'p')
|
||||
continue;
|
||||
if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
|
||||
continue; /* can't happen, toast_action would be 'p' */
|
||||
if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
|
||||
continue;
|
||||
if (toast_sizes[i] > biggest_size)
|
||||
{
|
||||
biggest_attno = i;
|
||||
biggest_size = toast_sizes[i];
|
||||
}
|
||||
}
|
||||
|
||||
if (biggest_attno < 0)
|
||||
break;
|
||||
|
||||
/*
|
||||
* Store this external
|
||||
*/
|
||||
i = biggest_attno;
|
||||
old_value = toast_values[i];
|
||||
toast_action[i] = 'p';
|
||||
toast_values[i] = toast_save_datum(rel, toast_values[i],
|
||||
toast_oldexternal[i], options);
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(old_value));
|
||||
toast_free[i] = true;
|
||||
|
||||
need_change = true;
|
||||
need_free = true;
|
||||
}
|
||||
|
||||
/*
|
||||
* In the case we toasted any values, we need to build a new heap tuple
|
||||
* with the changed values.
|
||||
*/
|
||||
if (need_change)
|
||||
{
|
||||
HeapTupleHeader olddata = newtup->t_data;
|
||||
HeapTupleHeader new_data;
|
||||
int32 new_header_len;
|
||||
int32 new_data_len;
|
||||
int32 new_tuple_len;
|
||||
|
||||
/*
|
||||
* Calculate the new size of the tuple.
|
||||
*
|
||||
* Note: we used to assume here that the old tuple's t_hoff must equal
|
||||
* the new_header_len value, but that was incorrect. The old tuple
|
||||
* might have a smaller-than-current natts, if there's been an ALTER
|
||||
* TABLE ADD COLUMN since it was stored; and that would lead to a
|
||||
* different conclusion about the size of the null bitmap, or even
|
||||
* whether there needs to be one at all.
|
||||
*/
|
||||
new_header_len = SizeofHeapTupleHeader;
|
||||
if (has_nulls)
|
||||
new_header_len += BITMAPLEN(numAttrs);
|
||||
new_header_len = MAXALIGN(new_header_len);
|
||||
new_data_len = heap_compute_data_size(tupleDesc,
|
||||
toast_values, toast_isnull);
|
||||
new_tuple_len = new_header_len + new_data_len;
|
||||
|
||||
/*
|
||||
* Allocate and zero the space needed, and fill HeapTupleData fields.
|
||||
*/
|
||||
result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
|
||||
result_tuple->t_len = new_tuple_len;
|
||||
result_tuple->t_self = newtup->t_self;
|
||||
result_tuple->t_tableOid = newtup->t_tableOid;
|
||||
new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
|
||||
result_tuple->t_data = new_data;
|
||||
|
||||
/*
|
||||
* Copy the existing tuple header, but adjust natts and t_hoff.
|
||||
*/
|
||||
memcpy(new_data, olddata, SizeofHeapTupleHeader);
|
||||
HeapTupleHeaderSetNatts(new_data, numAttrs);
|
||||
new_data->t_hoff = new_header_len;
|
||||
|
||||
/* Copy over the data, and fill the null bitmap if needed */
|
||||
heap_fill_tuple(tupleDesc,
|
||||
toast_values,
|
||||
toast_isnull,
|
||||
(char *) new_data + new_header_len,
|
||||
new_data_len,
|
||||
&(new_data->t_infomask),
|
||||
has_nulls ? new_data->t_bits : NULL);
|
||||
}
|
||||
else
|
||||
result_tuple = newtup;
|
||||
|
||||
/*
|
||||
* Free allocated temp values
|
||||
*/
|
||||
if (need_free)
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(toast_values[i]));
|
||||
|
||||
/*
|
||||
* Delete external values from the old tuple
|
||||
*/
|
||||
if (need_delold)
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
if (toast_delold[i])
|
||||
toast_delete_datum(rel, toast_oldvalues[i], false);
|
||||
|
||||
return result_tuple;
|
||||
}
|
||||
|
||||
|
||||
/* ----------
|
||||
* toast_flatten_tuple -
|
||||
*
|
||||
* "Flatten" a tuple to contain no out-of-line toasted fields.
|
||||
* (This does not eliminate compressed or short-header datums.)
|
||||
*
|
||||
* Note: we expect the caller already checked HeapTupleHasExternal(tup),
|
||||
* so there is no need for a short-circuit path.
|
||||
* ----------
|
||||
*/
|
||||
HeapTuple
|
||||
toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
|
||||
{
|
||||
HeapTuple new_tuple;
|
||||
int numAttrs = tupleDesc->natts;
|
||||
int i;
|
||||
Datum toast_values[MaxTupleAttributeNumber];
|
||||
bool toast_isnull[MaxTupleAttributeNumber];
|
||||
bool toast_free[MaxTupleAttributeNumber];
|
||||
|
||||
/*
|
||||
* Break down the tuple into fields.
|
||||
*/
|
||||
Assert(numAttrs <= MaxTupleAttributeNumber);
|
||||
heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
|
||||
|
||||
memset(toast_free, 0, numAttrs * sizeof(bool));
|
||||
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
/*
|
||||
* Look at non-null varlena attributes
|
||||
*/
|
||||
if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
|
||||
{
|
||||
struct varlena *new_value;
|
||||
|
||||
new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
|
||||
if (VARATT_IS_EXTERNAL(new_value))
|
||||
{
|
||||
new_value = heap_tuple_fetch_attr(new_value);
|
||||
toast_values[i] = PointerGetDatum(new_value);
|
||||
toast_free[i] = true;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Form the reconfigured tuple.
|
||||
*/
|
||||
new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
|
||||
|
||||
/*
|
||||
* Be sure to copy the tuple's identity fields. We also make a point of
|
||||
* copying visibility info, just in case anybody looks at those fields in
|
||||
* a syscache entry.
|
||||
*/
|
||||
new_tuple->t_self = tup->t_self;
|
||||
new_tuple->t_tableOid = tup->t_tableOid;
|
||||
|
||||
new_tuple->t_data->t_choice = tup->t_data->t_choice;
|
||||
new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
|
||||
new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
|
||||
new_tuple->t_data->t_infomask |=
|
||||
tup->t_data->t_infomask & HEAP_XACT_MASK;
|
||||
new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
|
||||
new_tuple->t_data->t_infomask2 |=
|
||||
tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
|
||||
|
||||
/*
|
||||
* Free allocated temp values
|
||||
*/
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(toast_values[i]));
|
||||
|
||||
return new_tuple;
|
||||
}
|
||||
|
||||
|
||||
/* ----------
|
||||
* toast_flatten_tuple_to_datum -
|
||||
*
|
||||
* "Flatten" a tuple containing out-of-line toasted fields into a Datum.
|
||||
* The result is always palloc'd in the current memory context.
|
||||
*
|
||||
* We have a general rule that Datums of container types (rows, arrays,
|
||||
* ranges, etc) must not contain any external TOAST pointers. Without
|
||||
* this rule, we'd have to look inside each Datum when preparing a tuple
|
||||
* for storage, which would be expensive and would fail to extend cleanly
|
||||
* to new sorts of container types.
|
||||
*
|
||||
* However, we don't want to say that tuples represented as HeapTuples
|
||||
* can't contain toasted fields, so instead this routine should be called
|
||||
* when such a HeapTuple is being converted into a Datum.
|
||||
*
|
||||
* While we're at it, we decompress any compressed fields too. This is not
|
||||
* necessary for correctness, but reflects an expectation that compression
|
||||
* will be more effective if applied to the whole tuple not individual
|
||||
* fields. We are not so concerned about that that we want to deconstruct
|
||||
* and reconstruct tuples just to get rid of compressed fields, however.
|
||||
* So callers typically won't call this unless they see that the tuple has
|
||||
* at least one external field.
|
||||
*
|
||||
* On the other hand, in-line short-header varlena fields are left alone.
|
||||
* If we "untoasted" them here, they'd just get changed back to short-header
|
||||
* format anyway within heap_fill_tuple.
|
||||
* ----------
|
||||
*/
|
||||
Datum
|
||||
toast_flatten_tuple_to_datum(HeapTupleHeader tup,
|
||||
uint32 tup_len,
|
||||
TupleDesc tupleDesc)
|
||||
{
|
||||
HeapTupleHeader new_data;
|
||||
int32 new_header_len;
|
||||
int32 new_data_len;
|
||||
int32 new_tuple_len;
|
||||
HeapTupleData tmptup;
|
||||
int numAttrs = tupleDesc->natts;
|
||||
int i;
|
||||
bool has_nulls = false;
|
||||
Datum toast_values[MaxTupleAttributeNumber];
|
||||
bool toast_isnull[MaxTupleAttributeNumber];
|
||||
bool toast_free[MaxTupleAttributeNumber];
|
||||
|
||||
/* Build a temporary HeapTuple control structure */
|
||||
tmptup.t_len = tup_len;
|
||||
ItemPointerSetInvalid(&(tmptup.t_self));
|
||||
tmptup.t_tableOid = InvalidOid;
|
||||
tmptup.t_data = tup;
|
||||
|
||||
/*
|
||||
* Break down the tuple into fields.
|
||||
*/
|
||||
Assert(numAttrs <= MaxTupleAttributeNumber);
|
||||
heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
|
||||
|
||||
memset(toast_free, 0, numAttrs * sizeof(bool));
|
||||
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
/*
|
||||
* Look at non-null varlena attributes
|
||||
*/
|
||||
if (toast_isnull[i])
|
||||
has_nulls = true;
|
||||
else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
|
||||
{
|
||||
struct varlena *new_value;
|
||||
|
||||
new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
|
||||
if (VARATT_IS_EXTERNAL(new_value) ||
|
||||
VARATT_IS_COMPRESSED(new_value))
|
||||
{
|
||||
new_value = heap_tuple_untoast_attr(new_value);
|
||||
toast_values[i] = PointerGetDatum(new_value);
|
||||
toast_free[i] = true;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Calculate the new size of the tuple.
|
||||
*
|
||||
* This should match the reconstruction code in toast_insert_or_update.
|
||||
*/
|
||||
new_header_len = SizeofHeapTupleHeader;
|
||||
if (has_nulls)
|
||||
new_header_len += BITMAPLEN(numAttrs);
|
||||
new_header_len = MAXALIGN(new_header_len);
|
||||
new_data_len = heap_compute_data_size(tupleDesc,
|
||||
toast_values, toast_isnull);
|
||||
new_tuple_len = new_header_len + new_data_len;
|
||||
|
||||
new_data = (HeapTupleHeader) palloc0(new_tuple_len);
|
||||
|
||||
/*
|
||||
* Copy the existing tuple header, but adjust natts and t_hoff.
|
||||
*/
|
||||
memcpy(new_data, tup, SizeofHeapTupleHeader);
|
||||
HeapTupleHeaderSetNatts(new_data, numAttrs);
|
||||
new_data->t_hoff = new_header_len;
|
||||
|
||||
/* Set the composite-Datum header fields correctly */
|
||||
HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
|
||||
HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
|
||||
HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
|
||||
|
||||
/* Copy over the data, and fill the null bitmap if needed */
|
||||
heap_fill_tuple(tupleDesc,
|
||||
toast_values,
|
||||
toast_isnull,
|
||||
(char *) new_data + new_header_len,
|
||||
new_data_len,
|
||||
&(new_data->t_infomask),
|
||||
has_nulls ? new_data->t_bits : NULL);
|
||||
|
||||
/*
|
||||
* Free allocated temp values
|
||||
*/
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
if (toast_free[i])
|
||||
pfree(DatumGetPointer(toast_values[i]));
|
||||
|
||||
return PointerGetDatum(new_data);
|
||||
}
|
||||
|
||||
|
||||
/* ----------
|
||||
* toast_build_flattened_tuple -
|
||||
*
|
||||
* Build a tuple containing no out-of-line toasted fields.
|
||||
* (This does not eliminate compressed or short-header datums.)
|
||||
*
|
||||
* This is essentially just like heap_form_tuple, except that it will
|
||||
* expand any external-data pointers beforehand.
|
||||
*
|
||||
* It's not very clear whether it would be preferable to decompress
|
||||
* in-line compressed datums while at it. For now, we don't.
|
||||
* ----------
|
||||
*/
|
||||
HeapTuple
|
||||
toast_build_flattened_tuple(TupleDesc tupleDesc,
|
||||
Datum *values,
|
||||
bool *isnull)
|
||||
{
|
||||
HeapTuple new_tuple;
|
||||
int numAttrs = tupleDesc->natts;
|
||||
int num_to_free;
|
||||
int i;
|
||||
Datum new_values[MaxTupleAttributeNumber];
|
||||
Pointer freeable_values[MaxTupleAttributeNumber];
|
||||
|
||||
/*
|
||||
* We can pass the caller's isnull array directly to heap_form_tuple, but
|
||||
* we potentially need to modify the values array.
|
||||
*/
|
||||
Assert(numAttrs <= MaxTupleAttributeNumber);
|
||||
memcpy(new_values, values, numAttrs * sizeof(Datum));
|
||||
|
||||
num_to_free = 0;
|
||||
for (i = 0; i < numAttrs; i++)
|
||||
{
|
||||
/*
|
||||
* Look at non-null varlena attributes
|
||||
*/
|
||||
if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
|
||||
{
|
||||
struct varlena *new_value;
|
||||
|
||||
new_value = (struct varlena *) DatumGetPointer(new_values[i]);
|
||||
if (VARATT_IS_EXTERNAL(new_value))
|
||||
{
|
||||
new_value = heap_tuple_fetch_attr(new_value);
|
||||
new_values[i] = PointerGetDatum(new_value);
|
||||
freeable_values[num_to_free++] = (Pointer) new_value;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Form the reconfigured tuple.
|
||||
*/
|
||||
new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
|
||||
|
||||
/*
|
||||
* Free allocated temp values
|
||||
*/
|
||||
for (i = 0; i < num_to_free; i++)
|
||||
pfree(freeable_values[i]);
|
||||
|
||||
return new_tuple;
|
||||
}
|
||||
Reference in New Issue
Block a user