*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/cluster.c,v 1.102 2002/12/06 05:00:10 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/cluster.c,v 1.103 2002/12/30 18:42:13 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "utils/syscache.h"
#include "utils/relcache.h"
+
/*
* We need one of these structs for each index in the relation to be
* clustered. It's basically the data needed by index_create() so
bool isclustered;
} IndexAttrs;
-/* This struct is used to pass around the information on tables to be
+/*
+ * This struct is used to pass around the information on tables to be
* clustered. We need this so we can make a list of them when invoked without
* a specific table/index pair.
*/
{
Oid tableOid;
Oid indexOid;
- bool isPrevious;
-} relToCluster;
+} RelToCluster;
+
+static void cluster_rel(RelToCluster *rv, bool recheck);
static Oid make_new_heap(Oid OIDOldHeap, const char *NewName);
static void copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex);
-static void recreate_indexattr(Oid OIDOldHeap, List *indexes);
+static List *get_indexattr_list(Relation OldHeap, Oid OldIndex);
+static void rebuild_indexes(Oid OIDOldHeap, List *indexes);
static void swap_relfilenodes(Oid r1, Oid r2);
-static void cluster_rel(relToCluster *rv);
-static bool check_cluster_ownership(Oid relOid);
-static List *get_tables_to_cluster(AclId owner);
+static bool check_cluster_permitted(Oid relOid);
+static List *get_tables_to_cluster(MemoryContext cluster_context);
+
+
+
+/*---------------------------------------------------------------------------
+ * This cluster code allows for clustering multiple tables at once. Because
+ * of this, we cannot just run everything on a single transaction, or we
+ * would be forced to acquire exclusive locks on all the tables being
+ * clustered, simultaneously --- very likely leading to deadlock.
+ *
+ * To solve this we follow a similar strategy to VACUUM code,
+ * clustering each relation in a separate transaction. For this to work,
+ * we need to:
+ * - provide a separate memory context so that we can pass information in
+ * a way that survives across transactions
+ * - start a new transaction every time a new relation is clustered
+ * - check for validity of the information on to-be-clustered relations,
+ * as someone might have deleted a relation behind our back, or
+ * clustered one on a different index
+ * - end the transaction
+ *
+ * The single-relation case does not have any such overhead.
+ *
+ * We also allow a relation being specified without index. In that case,
+ * the indisclustered bit will be looked up, and an ERROR will be thrown
+ * if there is no index with the bit set.
+ *---------------------------------------------------------------------------
+ */
+void
+cluster(ClusterStmt *stmt)
+{
+ if (stmt->relation != NULL)
+ {
+ /* This is the single-relation case. */
+ Oid tableOid,
+ indexOid = InvalidOid;
+ Relation rel;
+ RelToCluster rvtc;
+
+ /* Find and lock the table */
+ tableOid = RangeVarGetRelid(stmt->relation, false);
+
+ rel = heap_open(tableOid, AccessExclusiveLock);
+
+ /* Check permissions */
+ if (!check_cluster_permitted(tableOid))
+ elog(ERROR, "CLUSTER: You do not own relation %s",
+ stmt->relation->relname);
+
+ if (stmt->indexname == NULL)
+ {
+ List *index;
+
+ /* We need to find the index that has indisclustered set. */
+ foreach (index, RelationGetIndexList(rel))
+ {
+ HeapTuple idxtuple;
+ Form_pg_index indexForm;
+
+ indexOid = lfirsti(index);
+ idxtuple = SearchSysCache(INDEXRELID,
+ ObjectIdGetDatum(indexOid),
+ 0, 0, 0);
+ if (!HeapTupleIsValid(idxtuple))
+ elog(ERROR, "Cache lookup failed for index %u",
+ indexOid);
+ indexForm = (Form_pg_index) GETSTRUCT(idxtuple);
+ if (indexForm->indisclustered)
+ {
+ ReleaseSysCache(idxtuple);
+ break;
+ }
+ ReleaseSysCache(idxtuple);
+ indexOid = InvalidOid;
+ }
+
+ if (!OidIsValid(indexOid))
+ elog(ERROR, "CLUSTER: No previously clustered index found on table \"%s\"",
+ stmt->relation->relname);
+ }
+ else
+ {
+ /* The index is expected to be in the same namespace as the relation. */
+ indexOid = get_relname_relid(stmt->indexname,
+ rel->rd_rel->relnamespace);
+ if (!OidIsValid(indexOid))
+ elog(ERROR, "CLUSTER: cannot find index \"%s\" for table \"%s\"",
+ stmt->indexname, stmt->relation->relname);
+ }
+
+ rvtc.tableOid = tableOid;
+ rvtc.indexOid = indexOid;
+
+ /* close relation, keep lock till commit */
+ heap_close(rel, NoLock);
+
+ /* Do the job */
+ cluster_rel(&rvtc, false);
+ }
+ else
+ {
+ /*
+ * This is the "multi relation" case. We need to cluster all tables
+ * that have some index with indisclustered set.
+ */
+ MemoryContext cluster_context;
+ List *rv,
+ *rvs;
+
+ /*
+ * We cannot run this form of CLUSTER inside a user transaction block;
+ * we'd be holding locks way too long.
+ */
+ PreventTransactionChain((void *) stmt, "CLUSTER");
+
+ /*
+ * Create special memory context for cross-transaction storage.
+ *
+ * Since it is a child of QueryContext, it will go away even in case
+ * of error.
+ */
+ cluster_context = AllocSetContextCreate(QueryContext,
+ "Cluster",
+ ALLOCSET_DEFAULT_MINSIZE,
+ ALLOCSET_DEFAULT_INITSIZE,
+ ALLOCSET_DEFAULT_MAXSIZE);
+
+ /*
+ * Build the list of relations to cluster. Note that this lives in
+ * cluster_context.
+ */
+ rvs = get_tables_to_cluster(cluster_context);
+
+ /* Commit to get out of starting transaction */
+ CommitTransactionCommand(true);
+
+ /* Ok, now that we've got them all, cluster them one by one */
+ foreach (rv, rvs)
+ {
+ RelToCluster *rvtc = (RelToCluster *) lfirst(rv);
+
+ /* Start a new transaction for each relation. */
+ StartTransactionCommand(true);
+ SetQuerySnapshot(); /* might be needed for functional index */
+ cluster_rel(rvtc, true);
+ CommitTransactionCommand(true);
+ }
+
+ /* Start a new transaction for the cleanup work. */
+ StartTransactionCommand(true);
-static MemoryContext cluster_context = NULL;
+ /* Clean up working storage */
+ MemoryContextDelete(cluster_context);
+ }
+}
/*
- * cluster
+ * cluster_rel
*
* This clusters the table by creating a new, clustered table and
* swapping the relfilenodes of the new table and the old table, so
* same way we do for the relation. Since we are effectively bulk-loading
* the new table, it's better to create the indexes afterwards than to fill
* them incrementally while we load the table.
- *
- * Since we may open a new transaction for each relation, we have to
- * check that the relation still is what we think it is.
*/
-void
-cluster_rel(relToCluster *rvtc)
+static void
+cluster_rel(RelToCluster *rvtc, bool recheck)
{
Relation OldHeap,
OldIndex;
- List *indexes;
/* Check for user-requested abort. */
CHECK_FOR_INTERRUPTS();
- /* Check if the relation and index still exist before opening them
+ /*
+ * Since we may open a new transaction for each relation, we have to
+ * check that the relation still is what we think it is.
+ *
+ * If this is a single-transaction CLUSTER, we can skip these tests.
+ * We *must* skip the one on indisclustered since it would reject an
+ * attempt to cluster a not-previously-clustered index.
*/
- if (!SearchSysCacheExists(RELOID,
- ObjectIdGetDatum(rvtc->tableOid),
- 0, 0, 0) ||
+ if (recheck)
+ {
+ HeapTuple tuple;
+ Form_pg_index indexForm;
+
+ /*
+ * Check if the relation and index still exist before opening them
+ */
+ if (!SearchSysCacheExists(RELOID,
+ ObjectIdGetDatum(rvtc->tableOid),
+ 0, 0, 0) ||
!SearchSysCacheExists(RELOID,
ObjectIdGetDatum(rvtc->indexOid),
0, 0, 0))
- return;
-
- /* Check that the user still owns the relation */
- if (!check_cluster_ownership(rvtc->tableOid))
- return;
+ return;
- /* Check that the index is still the one with indisclustered set.
- * If this is a standalone cluster, skip this test.
- */
- if (rvtc->isPrevious)
- {
- HeapTuple tuple;
- Form_pg_index indexForm;
+ /* Check that the user still owns the relation */
+ if (!check_cluster_permitted(rvtc->tableOid))
+ return;
+ /*
+ * Check that the index is still the one with indisclustered set.
+ */
tuple = SearchSysCache(INDEXRELID,
ObjectIdGetDatum(rvtc->indexOid),
0, 0, 0);
+ if (!HeapTupleIsValid(tuple))
+ return; /* could have gone away... */
indexForm = (Form_pg_index) GETSTRUCT(tuple);
if (!indexForm->indisclustered)
{
/*
* We grab exclusive access to the target rel and index for the
- * duration of the transaction.
+ * duration of the transaction. (This is redundant for the single-
+ * transaction case, since cluster() already did it.)
*/
OldHeap = heap_open(rvtc->tableOid, AccessExclusiveLock);
elog(ERROR, "CLUSTER: cannot cluster system relation \"%s\"",
RelationGetRelationName(OldHeap));
- /* Save the information of all indexes on the relation. */
- indexes = get_indexattr_list(OldHeap, rvtc->indexOid);
-
- /* Drop relcache refcnts, but do NOT give up the locks */
+ /* Drop relcache refcnt on OldIndex, but keep lock */
index_close(OldIndex);
- heap_close(OldHeap, NoLock);
- /* rebuild_rel does all the dirty work */
- rebuild_rel(rvtc->tableOid, rvtc->indexOid, indexes, true);
+ /* rebuild_relation does all the dirty work */
+ rebuild_relation(OldHeap, rvtc->indexOid);
+
+ /* NB: rebuild_relation does heap_close() on OldHeap */
}
+/*
+ * rebuild_relation: rebuild an existing relation
+ *
+ * This is shared code between CLUSTER and TRUNCATE. In the TRUNCATE
+ * case, the new relation is built and left empty. In the CLUSTER case,
+ * it is filled with data read from the old relation in the order specified
+ * by the index.
+ *
+ * OldHeap: table to rebuild --- must be opened and exclusive-locked!
+ * indexOid: index to cluster by, or InvalidOid in TRUNCATE case
+ *
+ * NB: this routine closes OldHeap at the right time; caller should not.
+ */
void
-rebuild_rel(Oid tableOid, Oid indexOid, List *indexes, bool dataCopy)
+rebuild_relation(Relation OldHeap, Oid indexOid)
{
+ Oid tableOid = RelationGetRelid(OldHeap);
+ List *indexes;
Oid OIDNewHeap;
char NewHeapName[NAMEDATALEN];
ObjectAddress object;
- /*
- * If dataCopy is true, we assume that we will be basing the
- * copy off an index for cluster operations.
- */
- Assert(!dataCopy || OidIsValid(indexOid));
+ /* Save the information about all indexes on the relation. */
+ indexes = get_indexattr_list(OldHeap, indexOid);
+
+ /* Close relcache entry, but keep lock until transaction commit */
+ heap_close(OldHeap, NoLock);
+
/*
* Create the new heap, using a temporary name in the same namespace
* as the existing table. NOTE: there is some risk of collision with
/*
* Copy the heap data into the new table in the desired order.
*/
- if (dataCopy)
+ if (OidIsValid(indexOid))
copy_heap_data(OIDNewHeap, tableOid, indexOid);
/* To make the new heap's data visible (probably not needed?). */
/*
* Recreate each index on the relation. We do not need
- * CommandCounterIncrement() because recreate_indexattr does it.
+ * CommandCounterIncrement() because rebuild_indexes does it.
*/
- recreate_indexattr(tableOid, indexes);
+ rebuild_indexes(tableOid, indexes);
}
/*
* Get the necessary info about the indexes of the relation and
* return a list of IndexAttrs structures.
*/
-List *
+static List *
get_indexattr_list(Relation OldHeap, Oid OldIndex)
{
List *indexes = NIL;
palloc(sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
memcpy(attrs->classOID, indexForm->indclass,
sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
- attrs->isclustered = (OldIndex == indexOID);
+ /* We adjust the isclustered attribute to correct new state */
+ attrs->isclustered = (indexOID == OldIndex);
/* Name and access method of each index come from pg_class */
classTuple = SearchSysCache(RELOID,
* the new index (carrying the old index filenode along).
*/
static void
-recreate_indexattr(Oid OIDOldHeap, List *indexes)
+rebuild_indexes(Oid OIDOldHeap, List *indexes)
{
List *elem;
heap_close(relRelation, RowExclusiveLock);
}
-/*---------------------------------------------------------------------------
- * This cluster code allows for clustering multiple tables at once. Because
- * of this, we cannot just run everything on a single transaction, or we
- * would be forced to acquire exclusive locks on all the tables being
- * clustered. To solve this we follow a similar strategy to VACUUM code,
- * clustering each relation in a separate transaction. For this to work,
- * we need to:
- * - provide a separate memory context so that we can pass information in
- * a way that trascends transactions
- * - start a new transaction every time a new relation is clustered
- * - check for validity of the information on to-be-clustered relations,
- * as someone might have deleted a relation behind our back, or
- * clustered one on a different index
- * - end the transaction
- *
- * The single relation code does not have any overhead.
- *
- * We also allow a relation being specified without index. In that case,
- * the indisclustered bit will be looked up, and an ERROR will be thrown
- * if there is no index with the bit set.
- *---------------------------------------------------------------------------
- */
-void
-cluster(ClusterStmt *stmt)
-{
-
- /* This is the single relation case. */
- if (stmt->relation != NULL)
- {
- Oid indexOid = InvalidOid,
- tableOid;
- relToCluster rvtc;
- HeapTuple tuple;
- Form_pg_class classForm;
-
- tableOid = RangeVarGetRelid(stmt->relation, false);
- if (!check_cluster_ownership(tableOid))
- elog(ERROR, "CLUSTER: You do not own relation %s",
- stmt->relation->relname);
-
- tuple = SearchSysCache(RELOID,
- ObjectIdGetDatum(tableOid),
- 0, 0, 0);
- if (!HeapTupleIsValid(tuple))
- elog(ERROR, "Cache lookup failed for relation %u", tableOid);
- classForm = (Form_pg_class) GETSTRUCT(tuple);
-
- if (stmt->indexname == NULL)
- {
- List *index;
- Relation rel = RelationIdGetRelation(tableOid);
- HeapTuple ituple = NULL,
- idxtuple = NULL;
-
- /* We need to fetch the index that has indisclustered set. */
- foreach (index, RelationGetIndexList(rel))
- {
- Form_pg_index indexForm;
-
- indexOid = lfirsti(index);
- ituple = SearchSysCache(RELOID,
- ObjectIdGetDatum(indexOid),
- 0, 0, 0);
- if (!HeapTupleIsValid(ituple))
- elog(ERROR, "Cache lookup failed for relation %u", indexOid);
- idxtuple = SearchSysCache(INDEXRELID,
- ObjectIdGetDatum(HeapTupleGetOid(ituple)),
- 0, 0, 0);
- if (!HeapTupleIsValid(idxtuple))
- elog(ERROR, "Cache lookup failed for index %u", HeapTupleGetOid(ituple));
- indexForm = (Form_pg_index) GETSTRUCT(idxtuple);
- if (indexForm->indisclustered)
- break;
- indexOid = InvalidOid;
- }
- if (indexOid == InvalidOid)
- elog(ERROR, "CLUSTER: No previously clustered index found on table %s",
- stmt->relation->relname);
- RelationClose(rel);
- ReleaseSysCache(ituple);
- ReleaseSysCache(idxtuple);
- }
- else
- {
- /* The index is expected to be in the same namespace as the relation. */
- indexOid = get_relname_relid(stmt->indexname, classForm->relnamespace);
- }
- ReleaseSysCache(tuple);
-
- /* XXX Maybe the namespace should be reported as well */
- if (!OidIsValid(indexOid))
- elog(ERROR, "CLUSTER: cannot find index \"%s\" for table \"%s\"",
- stmt->indexname, stmt->relation->relname);
- rvtc.tableOid = tableOid;
- rvtc.indexOid = indexOid;
- rvtc.isPrevious = false;
-
- /* Do the job */
- cluster_rel(&rvtc);
- }
- else
- {
- /*
- * This is the "no relation" case. We need to cluster all tables
- * that have some index with indisclustered set.
- */
-
- relToCluster *rvtc;
- List *rv,
- *rvs;
-
- /*
- * We cannot run CLUSTER inside a user transaction block; if we were inside
- * a transaction, then our commit- and start-transaction-command calls
- * would not have the intended effect!
- */
- if (IsTransactionBlock())
- elog(ERROR, "CLUSTER cannot run inside a BEGIN/END block");
-
- /* Running CLUSTER from a function would free the function context */
- if (!MemoryContextContains(QueryContext, stmt))
- elog(ERROR, "CLUSTER cannot be called from a function");
- /*
- * Create special memory context for cross-transaction storage.
- *
- * Since it is a child of QueryContext, it will go away even in case
- * of error.
- */
- cluster_context = AllocSetContextCreate(QueryContext,
- "Cluster",
- ALLOCSET_DEFAULT_MINSIZE,
- ALLOCSET_DEFAULT_INITSIZE,
- ALLOCSET_DEFAULT_MAXSIZE);
-
- /*
- * Build the list of relations to cluster. Note that this lives in
- * cluster_context.
- */
- rvs = get_tables_to_cluster(GetUserId());
-
- /* Ok, now that we've got them all, cluster them one by one */
- foreach (rv, rvs)
- {
- rvtc = (relToCluster *)lfirst(rv);
-
- /* Start a new transaction for this relation. */
- StartTransactionCommand(true);
- cluster_rel(rvtc);
- CommitTransactionCommand(true);
- }
- }
-
- /* Start a new transaction for the cleanup work. */
- StartTransactionCommand(true);
-
- /* Clean up working storage */
- if (stmt->relation == NULL)
- {
- MemoryContextDelete(cluster_context);
- cluster_context = NULL;
- }
-}
-
-/* Checks if the user owns the relation. Superusers
- * are allowed to cluster any table.
+/*
+ * Checks if the user is allowed to cluster (ie, owns) the relation.
+ * Superusers are allowed to cluster any table.
*/
-bool
-check_cluster_ownership(Oid relOid)
+static bool
+check_cluster_permitted(Oid relOid)
{
/* Superusers bypass this check */
return pg_class_ownercheck(relOid, GetUserId());
}
-/* Get a list of tables that the current user owns and
+/*
+ * Get a list of tables that the current user owns and
* have indisclustered set. Return the list in a List * of rvsToCluster
* with the tableOid and the indexOid on which the table is already
* clustered.
*/
-List *
-get_tables_to_cluster(AclId owner)
+static List *
+get_tables_to_cluster(MemoryContext cluster_context)
{
Relation indRelation;
HeapScanDesc scan;
ScanKeyData entry;
HeapTuple indexTuple;
Form_pg_index index;
- relToCluster *rvtc;
+ MemoryContext old_context;
+ RelToCluster *rvtc;
List *rvs = NIL;
/*
- * Get all indexes that have indisclustered set. System
- * relations or nailed-in relations cannot ever have
- * indisclustered set, because CLUSTER will refuse to
- * set it when called with one of them as argument.
+ * Get all indexes that have indisclustered set and are owned by
+ * appropriate user. System relations or nailed-in relations cannot ever
+ * have indisclustered set, because CLUSTER will refuse to set it when
+ * called with one of them as argument.
*/
- indRelation = relation_openr(IndexRelationName, RowExclusiveLock);
- ScanKeyEntryInitialize(&entry, 0, Anum_pg_index_indisclustered,
- F_BOOLEQ, true);
+ indRelation = relation_openr(IndexRelationName, AccessShareLock);
+ ScanKeyEntryInitialize(&entry, 0,
+ Anum_pg_index_indisclustered,
+ F_BOOLEQ,
+ BoolGetDatum(true));
scan = heap_beginscan(indRelation, SnapshotNow, 1, &entry);
while ((indexTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
- MemoryContext old_context = NULL;
-
index = (Form_pg_index) GETSTRUCT(indexTuple);
- if (!check_cluster_ownership(index->indrelid))
+ if (!check_cluster_permitted(index->indrelid))
continue;
/*
- * We have to build the struct in a different memory context so
+ * We have to build the list in a different memory context so
* it will survive the cross-transaction processing
*/
-
old_context = MemoryContextSwitchTo(cluster_context);
- rvtc = (relToCluster *)palloc(sizeof(relToCluster));
- rvtc->indexOid = index->indexrelid;
+ rvtc = (RelToCluster *) palloc(sizeof(RelToCluster));
rvtc->tableOid = index->indrelid;
- rvtc->isPrevious = true;
- rvs = lcons((void *)rvtc, rvs);
+ rvtc->indexOid = index->indexrelid;
+ rvs = lcons(rvtc, rvs);
MemoryContextSwitchTo(old_context);
}
heap_endscan(scan);
- /*
- * Release the lock on pg_index. We will check the indexes
- * later again.
- *
- */
- relation_close(indRelation, RowExclusiveLock);
+ relation_close(indRelation, AccessShareLock);
+
return rvs;
}
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