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340 lines
9.4 KiB
C
340 lines
9.4 KiB
C
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/*-------------------------------------------------------------------------
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*
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* toasting.c
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* This file contains routines to support creation of toast tables
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*
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*
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* Portions Copyright (c) 1996-2006, 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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* $PostgreSQL: pgsql/src/backend/catalog/toasting.c,v 1.1 2006/07/31 01:16:37 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/tuptoaster.h"
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#include "access/xact.h"
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#include "catalog/dependency.h"
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#include "catalog/heap.h"
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#include "catalog/index.h"
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#include "catalog/indexing.h"
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#include "catalog/pg_namespace.h"
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#include "catalog/pg_opclass.h"
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#include "catalog/pg_type.h"
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#include "catalog/toasting.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "utils/builtins.h"
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#include "utils/syscache.h"
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static bool create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid);
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static bool needs_toast_table(Relation rel);
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/*
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* AlterTableCreateToastTable
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* If the table needs a toast table, and doesn't already have one,
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* then create a toast table for it.
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*
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* We expect the caller to have verified that the relation is a table and have
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* already done any necessary permission checks. Callers expect this function
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* to end with CommandCounterIncrement if it makes any changes.
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*/
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void
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AlterTableCreateToastTable(Oid relOid)
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{
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Relation rel;
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/*
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* Grab an exclusive lock on the target table, which we will NOT release
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* until end of transaction. (This is probably redundant in all present
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* uses...)
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*/
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rel = heap_open(relOid, AccessExclusiveLock);
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/* create_toast_table does all the work */
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(void) create_toast_table(rel, InvalidOid, InvalidOid);
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heap_close(rel, NoLock);
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}
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/*
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* Create a toast table during bootstrap
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*
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* Here we need to prespecify the OIDs of the toast table and its index
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*/
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void
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BootstrapToastTable(char *relName, Oid toastOid, Oid toastIndexOid)
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{
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Relation rel;
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rel = heap_openrv(makeRangeVar(NULL, relName), AccessExclusiveLock);
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/* Note: during bootstrap may see uncataloged relation */
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if (rel->rd_rel->relkind != RELKIND_RELATION &&
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rel->rd_rel->relkind != RELKIND_UNCATALOGED)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a table",
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relName)));
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/* create_toast_table does all the work */
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if (!create_toast_table(rel, toastOid, toastIndexOid))
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elog(ERROR, "\"%s\" does not require a toast table",
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relName);
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heap_close(rel, NoLock);
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}
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/*
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* create_toast_table --- internal workhorse
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*
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* rel is already opened and exclusive-locked
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* toastOid and toastIndexOid are normally InvalidOid, but during
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* bootstrap they can be nonzero to specify hand-assigned OIDs
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*/
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static bool
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create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid)
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{
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Oid relOid = RelationGetRelid(rel);
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HeapTuple reltup;
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TupleDesc tupdesc;
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bool shared_relation;
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Relation class_rel;
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Oid toast_relid;
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Oid toast_idxid;
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char toast_relname[NAMEDATALEN];
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char toast_idxname[NAMEDATALEN];
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IndexInfo *indexInfo;
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Oid classObjectId[2];
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ObjectAddress baseobject,
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toastobject;
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/*
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* Toast table is shared if and only if its parent is.
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*
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* We cannot allow toasting a shared relation after initdb (because
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* there's no way to mark it toasted in other databases' pg_class).
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*/
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shared_relation = rel->rd_rel->relisshared;
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if (shared_relation && !IsBootstrapProcessingMode())
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ereport(ERROR,
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(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
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errmsg("shared tables cannot be toasted after initdb")));
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/*
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* Is it already toasted?
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*/
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if (rel->rd_rel->reltoastrelid != InvalidOid)
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return false;
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/*
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* Check to see whether the table actually needs a TOAST table.
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*/
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if (!needs_toast_table(rel))
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return false;
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/*
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* Create the toast table and its index
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*/
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snprintf(toast_relname, sizeof(toast_relname),
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"pg_toast_%u", relOid);
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snprintf(toast_idxname, sizeof(toast_idxname),
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"pg_toast_%u_index", relOid);
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/* this is pretty painful... need a tuple descriptor */
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tupdesc = CreateTemplateTupleDesc(3, false);
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TupleDescInitEntry(tupdesc, (AttrNumber) 1,
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"chunk_id",
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OIDOID,
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-1, 0);
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TupleDescInitEntry(tupdesc, (AttrNumber) 2,
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"chunk_seq",
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INT4OID,
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-1, 0);
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TupleDescInitEntry(tupdesc, (AttrNumber) 3,
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"chunk_data",
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BYTEAOID,
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-1, 0);
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/*
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* Ensure that the toast table doesn't itself get toasted, or we'll be
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* toast :-(. This is essential for chunk_data because type bytea is
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* toastable; hit the other two just to be sure.
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*/
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tupdesc->attrs[0]->attstorage = 'p';
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tupdesc->attrs[1]->attstorage = 'p';
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tupdesc->attrs[2]->attstorage = 'p';
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/*
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* Note: the toast relation is placed in the regular pg_toast namespace
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* even if its master relation is a temp table. There cannot be any
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* naming collision, and the toast rel will be destroyed when its master
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* is, so there's no need to handle the toast rel as temp.
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*
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* XXX would it make sense to apply the master's reloptions to the toast
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* table?
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*/
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toast_relid = heap_create_with_catalog(toast_relname,
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PG_TOAST_NAMESPACE,
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rel->rd_rel->reltablespace,
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toastOid,
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rel->rd_rel->relowner,
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tupdesc,
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RELKIND_TOASTVALUE,
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shared_relation,
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true,
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0,
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ONCOMMIT_NOOP,
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(Datum) 0,
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true);
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/* make the toast relation visible, else index creation will fail */
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CommandCounterIncrement();
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/*
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* Create unique index on chunk_id, chunk_seq.
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*
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* NOTE: the normal TOAST access routines could actually function with a
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* single-column index on chunk_id only. However, the slice access
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* routines use both columns for faster access to an individual chunk. In
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* addition, we want it to be unique as a check against the possibility of
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* duplicate TOAST chunk OIDs. The index might also be a little more
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* efficient this way, since btree isn't all that happy with large numbers
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* of equal keys.
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*/
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indexInfo = makeNode(IndexInfo);
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indexInfo->ii_NumIndexAttrs = 2;
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indexInfo->ii_KeyAttrNumbers[0] = 1;
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indexInfo->ii_KeyAttrNumbers[1] = 2;
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indexInfo->ii_Expressions = NIL;
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indexInfo->ii_ExpressionsState = NIL;
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indexInfo->ii_Predicate = NIL;
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indexInfo->ii_PredicateState = NIL;
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indexInfo->ii_Unique = true;
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classObjectId[0] = OID_BTREE_OPS_OID;
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classObjectId[1] = INT4_BTREE_OPS_OID;
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toast_idxid = index_create(toast_relid, toast_idxname, toastIndexOid,
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indexInfo,
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BTREE_AM_OID,
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rel->rd_rel->reltablespace,
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classObjectId, (Datum) 0,
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true, false, true, false);
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/*
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* Store the toast table's OID in the parent relation's pg_class row
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*/
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class_rel = heap_open(RelationRelationId, RowExclusiveLock);
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reltup = SearchSysCacheCopy(RELOID,
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ObjectIdGetDatum(relOid),
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0, 0, 0);
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if (!HeapTupleIsValid(reltup))
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elog(ERROR, "cache lookup failed for relation %u", relOid);
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((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid = toast_relid;
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if (!IsBootstrapProcessingMode())
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{
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/* normal case, use a transactional update */
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simple_heap_update(class_rel, &reltup->t_self, reltup);
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/* Keep catalog indexes current */
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CatalogUpdateIndexes(class_rel, reltup);
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}
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else
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{
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/* While bootstrapping, we cannot UPDATE, so overwrite in-place */
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heap_inplace_update(class_rel, reltup);
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}
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heap_freetuple(reltup);
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heap_close(class_rel, RowExclusiveLock);
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/*
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* Register dependency from the toast table to the master, so that the
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* toast table will be deleted if the master is. Skip this in bootstrap
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* mode.
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*/
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if (!IsBootstrapProcessingMode())
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{
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baseobject.classId = RelationRelationId;
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baseobject.objectId = relOid;
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baseobject.objectSubId = 0;
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toastobject.classId = RelationRelationId;
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toastobject.objectId = toast_relid;
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toastobject.objectSubId = 0;
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recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
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}
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/*
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* Make changes visible
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*/
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CommandCounterIncrement();
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return true;
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}
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/*
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* Check to see whether the table needs a TOAST table. It does only if
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* (1) there are any toastable attributes, and (2) the maximum length
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* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
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* create a toast table for something like "f1 varchar(20)".)
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*/
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static bool
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needs_toast_table(Relation rel)
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{
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int32 data_length = 0;
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bool maxlength_unknown = false;
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bool has_toastable_attrs = false;
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TupleDesc tupdesc;
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Form_pg_attribute *att;
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int32 tuple_length;
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int i;
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tupdesc = rel->rd_att;
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att = tupdesc->attrs;
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for (i = 0; i < tupdesc->natts; i++)
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{
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if (att[i]->attisdropped)
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continue;
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data_length = att_align(data_length, att[i]->attalign);
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if (att[i]->attlen > 0)
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{
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/* Fixed-length types are never toastable */
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data_length += att[i]->attlen;
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}
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else
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{
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int32 maxlen = type_maximum_size(att[i]->atttypid,
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att[i]->atttypmod);
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if (maxlen < 0)
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maxlength_unknown = true;
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else
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data_length += maxlen;
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if (att[i]->attstorage != 'p')
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has_toastable_attrs = true;
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}
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}
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if (!has_toastable_attrs)
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return false; /* nothing to toast? */
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if (maxlength_unknown)
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return true; /* any unlimited-length attrs? */
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tuple_length = MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) +
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BITMAPLEN(tupdesc->natts)) +
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MAXALIGN(data_length);
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return (tuple_length > TOAST_TUPLE_THRESHOLD);
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}
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