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Avoid creating a TOAST table if we can prove that the maximum tuple
length is < TOAST_TUPLE_THRESHOLD, even with toastable column types present. For example, CREATE TABLE foo (f1 int, f2 varchar(100)) does not require a toast table, even though varchar is a toastable type.
This commit is contained in:
Tom Lane
parent
a5da56d320
commit
3d3ca010aa
@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.95 2000/08/21 17:22:32 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.96 2000/08/25 18:05:54 tgl Exp $
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*
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* NOTES
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* The PerformAddAttribute() code, like most of the relation
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@ -19,6 +19,7 @@
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*/
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#include "postgres.h"
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#include "access/tuptoaster.h"
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#include "catalog/catalog.h"
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#include "catalog/catname.h"
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#include "catalog/index.h"
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@ -52,6 +53,9 @@
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#include "access/genam.h"
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static bool needs_toast_table(Relation rel);
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/* --------------------------------
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* PortalCleanup
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* --------------------------------
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@ -715,6 +719,7 @@ systable_beginscan(Relation rel, const char *indexRelname, int nkeys, ScanKey en
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sysscan->scan = heap_beginscan(rel, false, SnapshotNow, nkeys, entry);
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return (void *) sysscan;
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}
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static void
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systable_endscan(void *scan)
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{
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@ -731,6 +736,7 @@ systable_endscan(void *scan)
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heap_endscan(sysscan->scan);
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pfree(scan);
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}
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static HeapTuple
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systable_getnext(void *scan)
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{
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@ -780,6 +786,7 @@ find_attribute_walker(Node *node, int attnum)
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}
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return expression_tree_walker(node, find_attribute_walker, (void *) attnum);
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}
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static bool
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find_attribute_in_node(Node *node, int attnum)
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{
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@ -1377,17 +1384,14 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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HeapTuple reltup;
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HeapTupleData classtuple;
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TupleDesc tupdesc;
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Form_pg_attribute *att;
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Relation class_rel;
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Buffer buffer;
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Relation ridescs[Num_pg_class_indices];
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Oid toast_relid;
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Oid toast_idxid;
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bool has_toastable_attrs = false;
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int i;
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char toast_relname[NAMEDATALEN + 1];
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char toast_idxname[NAMEDATALEN + 1];
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Relation toast_rel;
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Relation toast_idxrel;
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IndexInfo *indexInfo;
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Oid classObjectId[1];
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@ -1400,15 +1404,23 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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#endif
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/*
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* lock the pg_class tuple for update
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* Grab an exclusive lock on the target table, which we will NOT
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* release until end of transaction.
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*/
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rel = heap_openr(relationName, AccessExclusiveLock);
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myrelid = RelationGetRelid(rel);
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/*
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* lock the pg_class tuple for update (is that really needed?)
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*/
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class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
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reltup = SearchSysCacheTuple(RELNAME, PointerGetDatum(relationName),
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0, 0, 0);
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if (!HeapTupleIsValid(reltup))
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elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
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relationName);
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class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
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classtuple.t_self = reltup->t_self;
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switch (heap_mark4update(class_rel, &classtuple, &buffer))
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{
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@ -1421,42 +1433,6 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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reltup = heap_copytuple(&classtuple);
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ReleaseBuffer(buffer);
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/*
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* Grab an exclusive lock on the target table, which we will NOT
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* release until end of transaction.
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*/
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rel = heap_openr(relationName, AccessExclusiveLock);
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myrelid = RelationGetRelid(rel);
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/*
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* Check if there are any toastable attributes on the table
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*/
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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]->attstorage != 'p')
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{
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has_toastable_attrs = true;
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break;
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}
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}
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if (!has_toastable_attrs)
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{
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if (silent)
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{
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heap_close(rel, NoLock);
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heap_close(class_rel, NoLock);
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heap_freetuple(reltup);
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return;
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}
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elog(ERROR, "ALTER TABLE: relation \"%s\" has no toastable attributes",
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relationName);
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}
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/*
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* XXX is the following check sufficient? At least it would
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* allow to create TOAST tables for views. But why not - someone
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@ -1480,9 +1456,26 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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}
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elog(ERROR, "ALTER TABLE: relation \"%s\" already has a toast table",
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relationName);
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relationName);
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}
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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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{
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if (silent)
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{
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heap_close(rel, NoLock);
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heap_close(class_rel, NoLock);
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heap_freetuple(reltup);
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return;
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}
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elog(ERROR, "ALTER TABLE: relation \"%s\" does not need a toast table",
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relationName);
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}
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/*
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* Create the toast table and its index
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*/
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@ -1518,8 +1511,9 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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* collision, and the toast rel will be destroyed when its master is,
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* so there's no need to handle the toast rel as temp.
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*/
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heap_create_with_catalog(toast_relname, tupdesc, RELKIND_TOASTVALUE,
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false, true);
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toast_relid = heap_create_with_catalog(toast_relname, tupdesc,
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RELKIND_TOASTVALUE,
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false, true);
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/* make the toast relation visible, else index creation will fail */
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CommandCounterIncrement();
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@ -1540,18 +1534,18 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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BTREE_AM_OID, classObjectId,
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false, false, true);
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/* make the index visible in this transaction */
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CommandCounterIncrement();
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/*
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* Update toast rel's pg_class entry to show that it has an index.
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* NOTE this also does CommandCounterIncrement() to make index visible.
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*/
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setRelhasindexInplace(toast_relid, true, false);
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/*
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* Get the OIDs of the newly created objects
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* Get the OID of the newly created index
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*/
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toast_rel = heap_openr(toast_relname, NoLock);
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toast_relid = RelationGetRelid(toast_rel);
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heap_close(toast_rel, NoLock);
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toast_rel = index_openr(toast_idxname);
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toast_idxid = RelationGetRelid(toast_rel);
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index_close(toast_rel);
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toast_idxrel = index_openr(toast_idxname);
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toast_idxid = RelationGetRelid(toast_idxrel);
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index_close(toast_idxrel);
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/*
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* Store the toast table- and index-Oid's in the relation tuple
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@ -1569,36 +1563,6 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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heap_freetuple(reltup);
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/*
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* Finally update the toast relations pg_class tuple to say
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* it has an index.
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*/
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reltup = SearchSysCacheTuple(RELNAME, PointerGetDatum(toast_relname),
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0, 0, 0);
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if (!HeapTupleIsValid(reltup))
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elog(ERROR, "ALTER TABLE: just created toast relation \"%s\" not found",
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toast_relname);
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classtuple.t_self = reltup->t_self;
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switch (heap_mark4update(class_rel, &classtuple, &buffer))
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{
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case HeapTupleSelfUpdated:
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case HeapTupleMayBeUpdated:
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break;
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default:
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elog(ERROR, "couldn't lock pg_class tuple");
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}
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reltup = heap_copytuple(&classtuple);
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ReleaseBuffer(buffer);
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((Form_pg_class) GETSTRUCT(reltup))->relhasindex = true;
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heap_update(class_rel, &reltup->t_self, reltup, NULL);
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CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, ridescs);
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CatalogIndexInsert(ridescs, Num_pg_class_indices, class_rel, reltup);
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CatalogCloseIndices(Num_pg_class_indices, ridescs);
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heap_freetuple(reltup);
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/*
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* Close relations and make changes visible
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*/
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@ -1608,6 +1572,56 @@ AlterTableCreateToastTable(const char *relationName, bool silent)
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CommandCounterIncrement();
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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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data_length = att_align(data_length, att[i]->attlen, 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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/*
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@ -8,7 +8,7 @@
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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/adt/format_type.c,v 1.3 2000/08/21 18:23:18 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/format_type.c,v 1.4 2000/08/25 18:05:54 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -20,6 +20,7 @@
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#include "fmgr.h"
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#include "catalog/pg_type.h"
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#include "utils/builtins.h"
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#include "utils/numeric.h"
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#include "utils/syscache.h"
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#define MAX_INT32_LEN 11
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@ -214,6 +215,53 @@ format_type_internal(Oid type_oid, int32 typemod)
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}
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/*
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* type_maximum_size --- determine maximum length of a varlena column
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*
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* If the max length is indeterminate, return -1. In particular, we return
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* -1 for any type not known to this routine. We assume the caller has
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* already determined that the type is a varlena type, so it's not
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* necessary to look up the type's pg_type tuple here.
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*
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* This may appear unrelated to format_type(), but in fact the two routines
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* share knowledge of the encoding of typmod for different types, so it's
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* convenient to keep them together.
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*/
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int32
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type_maximum_size(Oid type_oid, int32 typemod)
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{
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if (typemod <= 0)
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return -1;
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switch (type_oid)
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{
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case BPCHAROID:
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case VARCHAROID:
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/* typemod includes varlena header */
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return typemod;
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case NUMERICOID:
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/* precision (ie, max # of digits) is in upper bits of typmod */
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if (typemod > VARHDRSZ)
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{
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int precision = ((typemod - VARHDRSZ) >> 16) & 0xffff;
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/* Numeric stores 2 decimal digits/byte, plus header */
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return (precision + 1) / 2 + NUMERIC_HDRSZ;
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}
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break;
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case VARBITOID:
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case ZPBITOID:
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/* typemod is the (max) number of bits */
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return (typemod + (BITSPERBYTE-1)) / BITSPERBYTE
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+ 2 * sizeof(int32);
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}
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/* Unknown type, or unlimited-length type such as 'text' */
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return -1;
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}
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/*
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* oidvectortypes - converts a vector of type OIDs to "typname" list
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: builtins.h,v 1.134 2000/08/24 03:29:14 tgl Exp $
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* $Id: builtins.h,v 1.135 2000/08/25 18:05:53 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -583,5 +583,6 @@ extern Datum PG_char_to_encoding(PG_FUNCTION_ARGS);
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/* format_type.c */
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extern Datum format_type(PG_FUNCTION_ARGS);
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extern Datum oidvectortypes(PG_FUNCTION_ARGS);
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extern int32 type_maximum_size(Oid type_oid, int32 typemod);
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#endif /* BUILTINS_H */
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